Note: Within nine months from the publication of the mention of the grant of the European patent, any person may givenotice to the European Patent Office of opposition to the European patent granted. Notice of opposition shall be filed ina written reasoned statement. It shall not be deemed to have been filed until the opposition fee has been paid. (Art.99(1) European Patent Convention).

Printed by Jouve, 75001 PARIS (FR)

Europäisches Patentamt

European Patent Office

Office européen des brevets

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(12) EUROPEAN PATENT SPECIFICATION

(45) Date of publication and mentionof the grant of the patent:29.01.2003 Bulletin 2003/05

(21) Application number: 97932899.4

(22) Date of filing: 03.07.1997

(51) Int Cl.7: E21B 23/00, E21B 23/04,E21B 4/18

(86) International application number:PCT/GB97/01868

(87) International publication number:WO 98/001651 (15.01.1998 Gazette 1998/02)

(54) WELLBORE TRACTOR

ZIEHVORRICHTUNG FÜR BOHRLÖCHER

TRACTEUR POUR FORAGE

(84) Designated Contracting States:DE DK GB NL

(30) Priority: 03.07.1996 US 675176

(43) Date of publication of application:27.10.1999 Bulletin 1999/43

(73) Proprietor: CTES, L.C.Conroe, TX 77303 (US)

(72) Inventors:• NEWMAN, Kenneth, Ray

Willis, TX 77378-6625 (US)

• HAVER, Nelson, AlanSpring, TX 77389 (US)

• SPELLER, David, JosephHouston, TX 77095 (US)

(74) Representative: Lucas, Brian RonaldLucas & Co.135 Westhall RoadWarlingham Surrey CR6 9HJ (GB)

(56) References cited:EP-A- 0 149 528 WO-A-97/08418US-A- 4 558 751

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Description

[0001] This invention relates to wellbore tractors and,in one particular aspect, to a tractor system useful in anon-vertical wellbore to move continuously a tubularstring, a wireline, a cable, or coiled tubing.[0002] In vertical wellbores and semi-vertical well-bores which are not highly deviated, wirelines, cable,coiled tubing, tubular strings and tools introduced intothe wellbore move down into the wellbore by the forceof gravity.[0003] Cable or wireline reaches a deviation threshold(e.g. for certain systems a deviation of about 70° fromthe vertical, e.g. wireline systems) at which gravity nolonger provides the necessary force and resulting ten-sion to move the cable or wireline down and through awellbore.[0004] To a certain extent, tubular strings and coiledtubing can be pushed through a deviated wellbore, evenpart of a horizontally or upwardly-directed wellbore; butthere is a limit to the length of coiled tubing that can bepushed in this manner. When compressive loads in atubular string become large enough, the tubular stringforms a helical jam in the wellbore (cased or uncased),and further insertion movement is prevented. This isknown as "helical lockup."[0005] US-A-4 558 751 discloses an apparatus forpropelling equipment through a fluid filled conduit. Theapparatus comprises two bodies which can engage theinner surface of the conduit, and a biasing element con-nected therebetween. The biasing element responds toa reduction and increase in fluid pressure within the con-duit by moving the two bodies toward and away fromone another respectively. Thus, by selective engage-ment with the inner surface, the apparatus can movethrough the conduit in an "inchworm" fashion. It will benoted that when engaged with the inner surface eachbody is not movable relative thereto.[0006] With reference to WO 97/08418 the applicanthas voluntarily limited the scope of the present applica-tion for all designated countries, despite the fact that WO97/08418 is an intervening national right in the UK only.[0007] The present invention relates to a continuous,or nearly-continuous motion, wellbore tractor systemwhich has at least one slip unit (and in certain embodi-ments two slip units) with retractable slips for engagingan interior wall of casing or of a wellbore, and at leastone movement unit for moving an item such as, but notlimited to, a tubular string, cable, wireline, or coiled tub-ing through a wellbore. In one aspect, while the slip unitor slip units are involved in engaging and disengagingfrom a wellbore, the movement unit(s) move the item.In one aspect of such a system, with two slip units andtwo movement units, power strokes of the movementunits overlap, so that there is no interruption in the mo-tion of the item.[0008] It is, therefore, an object of the present inven-tion to provide wellbore tractor devices and methods of

their use.[0009] Accordingly, the present invention provides awellbore tractor system for moving a component alonga wellbore or like passage extending from the surfaceto an underground location, the system comprising:

a body connectable to the component, the bodyhaving mounted on it anchoring means for selec-tively engaging the inner surface of the wellbore ina releasable manner;means for moving the component longitudinally rel-ative to the anchoring means when engaged withthe inner surface of the wellbore, andmeans for moving the anchoring means longitudi-nally with respect to the component, in the directionof travel thereof, after the anchoring means hasbeen disengaged from the inner surface of the well-bore,

characterised in that said body is movable relativeto said anchoring means when engaged with the innersurface of the wellbore to effect movement of said com-ponent along the wellbore, and in that said anchoringmeans comprise slips.[0010] Further features are set out in Claim 2 to 8.[0011] According to another aspect of the present in-vention there is provided a method of moving a payloadwhich comprises the step of using a system in accord-ance with the present invention to move said payloadalong a wellbore.[0012] According to another aspect of the present in-vention there is provided a method of moving a compo-nent along a wellbore or like passage extending fromthe surface to an underground location, which methodcomprises the steps of:

(1) connecting a wellbore tractor comprising a bodyand first anchoring means mounted on said body,to a component and inserting said wellbore tractorand component into a wellbore;(2) engaging the inner surface of said wellbore withsaid first anchoring means;(3) moving said component relative to said anchor-ing means when engaged with said inner surface;(4) releasing said first anchoring means from saidinner surface; and(5) advancing said first anchoring means in the di-rection of travel of the component;

characterised in that said first anchoring meanscomprise slips and in that step (3) is by moving said bodyrelative to said first anchoring means.[0013] Further steps of the method are set out inClaims 11 and 12.[0014] In one embodiment the present invention dis-closes a wellbore tractor system for moving an itemthrough a wellbore, the wellbore extending from earthsurface to an underground location, the system having

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a body connected to the item, first setting means on thebody for selectively and releasably anchoring the sys-tem in a wellbore, first movement means on the bodyfor moving the body and the item, the first movementmeans having a first power stroke. The wellbore tractorhas second setting means for selectively and releasablyanchoring the system in the wellbore, the second settingmeans being spaced apart from the first setting means,and second movement means on the body providing asecond power stroke for moving the body and the item,the second movement means being spaced apart fromthe first movement means. In this a wellbore tractor sys-tem the first power stroke temporally overlaps the sec-ond power stroke, so that the item is moved continuous-ly.[0015] The item being moved into the wellbore maybe a tubular string of interconnected tubular membersor a wireline. The wellbore tractor system of this inven-tion may comprise first setting means including a selec-tively-movable first sleeve, and first slip means pivotablyconnected to the first sleeve for engaging an interior wallof the wellbore so that, upon movement of the firstsleeve in a first direction, the first slip means is movedinto engagement with the interior wall and, upon move-ment of the first sleeve in a second direction the first slipmeans is moved out of engagement with the interiorwall. It may also comprise hydraulic apparatus for mov-ing the selectively-movable first sleeve, the hydraulicapparatus being powered by fluid under pressurepumped into the hydraulic apparatus from the earth'ssurface through the item being moved. The wellboretractor system may comprise a selectively-movable sec-ond sleeve, and second slip means pivotably connectedto the second sleeve for engaging an interior wall of thewellbore so that, upon movement of the second sleevein a first direction, the second slip means is moved intoengagement with the interior wall and, upon movementof the second sleeve in a second direction, the secondslip means is moved out of engagement with the interiorwall.[0016] The present invention will now be described,by way of example, with reference to the accompanyingdrawings, in which:

Fig. 1A is a side view in cross-section of a wellboretractor system according to the present invention;Fig. 1B is an enlargement of a portion of the systemof Fig. 1A;Fig. 1C1 and 1C2 is an enlargement of a portion ofthe system of Fig. 1A, and includes a schematic rep-resentation of an hydraulic circuit of the system;Fig. 2A is a side view in cross-section of a secondembodiment of the present invention;Fig. 2B is an enlarged view of part of the system ofFig. 2A;Figs. 3A - 3E illustrate a sequence of operations ofthe system of Fig. 2;Fig. 4 is a side view in cross-section of a third em-

bodiment of the present invention;Fig. 5 is a side view in cross-section of a fourth em-bodiment of the present invention; andFigs. 6A - 6D illustrate a sequence of operation ofthe system of Fig. 5.

[0017] As shown in Figs. 1A - 1C, a wellbore tractorsystem 100 according to the present invention has twotractor units, an upper unit 150 and a lower unit 160. Theupper half 150 has a mud motor 102 in fluid communi-cation with a wellbore tubing string 101 such as is typi-cally interconnected with a wellbore mud motor. An in-flatable hydraulic fluid reservoir bladder 103 is disposedin a chamber 151 in a housing 152. The mud motor 102is powered by pressurized fluid selectively suppliedthrough the tubing 101, into the housing 152, to the mudmotor 102. Fluid exhausts from the mud motor 102through ports 106 which are in fluid communication withan internal bore 118 through the system 100.[0018] The mud motor 102 powers a pump 107 whichpumps fluid under pressure from the bladder 103 in aline 105 and then in a line 128 through an annulus 108to the tractor units 150 and 160. The annulus 108 is be-tween an inner housing 110 which is secured to a middlehousing 109, both of which are secured to the housing152.The tractor units advance the middle housing 109 (andhence the tubing string 101) by pushing against shoul-ders projecting outwardly from the middle housing 109,an upper shoulder 189 in the upper unit 150 and a lowershoulder 190 in the lower unit 160. Hydraulic circuit pip-ing and other elements interconnecting the pump 107and various tractor unit control valves and ports are lo-cated within the annulus 108. By way of a port 104, thepressure of fluid in an annulus 153 between an innerwall 134 of a wellbore 130 and an outer wall of the mudmotor housing 152 is applied to the bladder 103. In thehydraulic circuit shown in Figs. 1B, 1C1 and 1C2, pump107 pumps fluid under pressure to a control valve 161and to a control valve 125. The control valve 161 con-trols the lower unit 160, and the control valve 125 anda second control valve 126 control the upper unit 150.[0019] A valve member 114 disposed around the mid-dle housing 109 has a body 154 with ribs 155, 156, 157which define a plurality of fluid communication cham-bers 170, 171, 172, and 173. A sleeve 133 disposedaround the middle housing 109 is movable to move thevalve member 114 so that various ports are in fluid com-munication via the communication chambers 170-173.These ports include ports 111, 112, 113, 115, 116 and117.[0020] Pivotably secured to the outer housing 127 isa first slip arm 131, which is also pivotably secured atits other end to a slip 123. A second slip arm 132 has afirst end pivotably secured to the slip 123, and a secondend pivotably secured to the sleeve 133. As the outerhousing 127 moves up with respect to the sleeve 133and with respect to the middle housing 109, the slip arms

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131, 132 pivot to move the slip 123 of the upper unit 150outwardly to contact and engage the inner wall 134 of awellbore 130.[0021] The upper unit 150 has an outer housing 127which is movable with respect to the valve member 114and the middle housing 109. The lower unit 160 has asimilar outer housing 147, slip arms 148 and 149, andslip 146 which operate in a similar fashion.[0022] The sleeve 133 has an activating ring 122 hav-ing a shoulder 197 which upon contact moves a pivotarm 121 of the valve member 114, thereby moving thevalve member 114. A spring 120 biases the pivot arm121, and hence the valve member 114, initially down-wardly. An abutment surface 200 on the interior of thesleeves 133 is movable to contact valve stems 144 and178 of the control valves 125 and 126 respectively tomove and operate these control valves. O-rings 201 incorresponding recesses seal interfaces between vari-ous elements.[0023] The control valve 125 is disposed in a chamberin the upper shoulder 189 of the middle housing 109 andhas a valve member 177 which is connected to the valvestem 178 and is movable to permit fluid flow betweenports 174 and 175 or between ports 175 and 176. Thecontrol valve 125 controls the fluid flow into a retractchamber 182 or a power chamber 183 of the upper unit150.[0024] The port 174 is in fluid communication with aflow line 192 to power chamber 183. The port 175 is influid communication with a flow line 139 which is in fluidcommunication with pump 107. The port 176 is in fluidcommunication with a flow line 191 which is connectedto a retract chamber 182.[0025] The control valve 126 is diametrically opposedto the control valve 125 and works simultaneously in tan-dem with it. The control valve 126 is also disposed in achamber in the upper shoulder 189 of the middle hous-ing 109 and has a valve member 140 which is connectedto the valve stem 144 and is movable to permit fluid flowbetween ports 141 and 142 or between ports 142 and143. The control valve 126 controls the flow of fluid fromthe retract chamber 182 or from the power chamber 183of the upper unit 150. The port 143 is in fluid communi-cation with a flow line 167 which is connected to the pow-er chamber 183. The port 142 is in fluid communicationwith flow line 135 which leads back to bladder 103. Theport 141 is in fluid communication with a flow line 166which is connected to the retract chamber 182.[0026] In a typical cycle of operation of the system100, the system 100 connected to a tubular string 101is introduced into the wellbore 130 and located at a de-sired location therein, e.g. by the force of gravity on thesystem 100. At that location, motive fluid under pressureis supplied down through the tubular string 101 to themud motor 102. The mud motor 102 drives the pump107 which in turn pumps fluid under pressure from thebladder 103, through the line 119, into the annular space108 for provision to the various valves that control the

tractor units 150 and 160.[0027] The pump 107 pumps hydraulic fluid underpressure into a line 199, to a line 138, to the port 112and to line 139 to the port 175. With the valve member114 in the position shown in Fig. 1C, fluid flows from theport 112, into the chamber 173, to the port 111, to a line194, and down to the lower unit 160. The fluid flows intoa power chamber 181 of the lower unit 160 and flowsfrom the power chamber 181, through a port 187, into achamber 186 setting the slip 146 of the lower unit. Thefluid in the chamber 181 then pushes on the lower shoul-der 190 and moves the middle housing 109 down. thefluid in chamber 180 escapes via line 195 through port115 in valve member 114 and through port 116 to blad-der 103. The sleeve 133 of the upper unit 150 simulta-neously moves in a similar fashion by fluid entering port175 via line 139 into valve 161 which directs fluid intoupper power chamber 183 via line 192. The fluid inchamber 182 escapes via line 166 into valve 140 and tobladder 103.[0028] The system 100/tubing 101 is moving down-wardly in the wellbore at this point in the cycle.[0029] As the sleeve 133 moves upwardly, the shoul-der 197 of the activating ring 122 contacts and thenpushes on the pivot arm 121, compressing the spring120, and moving the valve member 114 upwardly (asviewed in Fig. 1C).[0030] As the pivot arm 121 is moves toward a notch129, the valve member 114 move upwardly and fluidflow is stopped between the ports 111 and 112, cuttingoff the flow of fluid to the power chamber 181 of the lowerunit 160. At this point the power stroke of the lower unit160 ceases. While the activating ring 122 moves up-wardly over the pivot arm 121 in the notch 129, the valvemember 114 is prevented from moving downwardly, andfluid flows through the port 112, through a chamber 172,through a port 113, to a line 195, to a retract chamber180 of the lower unit 160, and retraction commencingthe retraction cycle.[0031] The size, length, disposition, and configurationof the activating ring 122 determine the length of timethat fluid flows from the power chamber 181 of the lowerunit 160. During this period, there is no fluid communi-cation between the ports 111 and 112. As the retractchamber 180 begins to fill with fluid under pressure andmove the sleeve 133 downwardly, fluid in the powerchamber 181 escapes through the line 194, to a line 137,to the port 117, to the chamber 170, to the port 116, tothe line 193, to the line 136, and back to the bladder 103.[0032] Once the activating ring 122 has moved up-wardly beyond the notch 129, the pivot arm 121 is freedand is pivoted outwardly by the spring 120, and the valvemember 114 is freed to move downwardly, again posi-tioning the chamber 173 so that fluid communication be-tween the ports 111 and 112 occurs. Fluid flows into thelower power chamber 181, and a new power stroke ofthe lower unit 160 commences. At every moment in thecycle, power is provided to move the tubular string 101

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by the upper unit 150, by the lower unit 160, or by both.[0033] The control valves 125 and 126 control the flowof fluid under pressure to and from the upper unit 150.When the sleeve 133 has moved upwardly to a sufficientextent, the abutment surface 200 contacts the valvestems 144 and 178. Subsequent movement of the valvemembers 140 and 177 results in fluid escaping from theupper power chamber 183 to bladder 103 via line 167and valve 126 and fluid into the upper retract chamber182 via line 191 and valve 125, shifting the upper unit150 from a power stroke to a retraction stroke.[0034] When the retraction stroke of the upper unit150 begins, the power stroke of the lower unit 160 isalready in progress (due to the timed and controlled in-troduction of fluid into the lower power chamber 181 asdescribed above). When the retract stroke of the lowerpower unit 160 begins, the power stroke of the upperunit 150 is already in progress. Thus power is providedfor the continuous movement of the tubular string 101.[0035] When the sleeve 133 of the upper unit 150moves back downwardly, the valve stems 144 and 178contact an upper abutment surface 203 which shifts thevalve members 140 and 177 back to their initial positions(e.g. as in Fig. 1C) and a power stroke of the upper unit150 commences.[0036] A payload 158 such as logging tools, perforat-ing guns, sand clean-out equipment or any item run onthe end of coiled tubing or on the end of a wireline) isconnected to the bottom of the middle housing 109.[0037] Another embodiment of the invention is shownin Fig. 4, and is used to move a tubular string 302. Ofcourse this system may be used to move pipe, cable,casing, or coiled tubing. A payload 324 is connected toa lower end 328 of a hollow mandrel 327. An upper end329 of the mandrel 327 is connected to the tubing 302,and the bore 337 of the mandrel 327 is in fluid commu-nication with a flow bore 338 through the tubing 302.[0038] Fluid at relatively high pressure is pumpeddown the tubing 302 into the mandrel 327, such as froma surface mud pump which pumps high-pressure liquid,which enters the mandrel 327 and exits it through ex-haust ports 323 near the lower end 328. Preferably theliquid is at a sufficiently high pressure that the fluid pres-sure within the mandrel 327 is higher than the pressureof fluid in a wellbore 334 through which the system 300extends.[0039] The high pressure liquid enters an expansionchamber through a port 308. The expansion chamber307 is defined by an exterior surface of the mandrel 327,an interior surface of a slip housing 314, and a mandrelseal 309. The fluid also enters a slip set chamber 304through a port 305 which is in fluid communication withthe expansion chamber 307. The slip set chamber 304is defined by an outer surface of the slip housing 314,and an inner surface of an upper housing 303.[0040] The increased pressure in the slip set chamber304 moves the upper housing 303 against a spring 306and toward a bottom housing 321. The spring 306 ini-

tially abuts an inner shoulder 335 on the upper housing303 and a lower outer shoulder 336 of the slip set hous-ing 314, and urges these two members apart. Thismovement of the upper housing 303 (down in a verticalwellbore, laterally in a horizontal wellbore, at a diagonalin an inclined wellbore) toward the lower housing 321results in the setting of slips 311 against an inner wall334 of the wellbore 330, setting the slips and centeringthe system 300 in the wellbore 330.[0041] Each slip 311 has one end pivotably connectedto a lower slip arm 312 which has a lower end pivotablyconnected to the slip housing 314, and its other end piv-otably connected to an upper slip arm 310 which has itsupper end pivotably connected to the upper housing303. Setting of the slips 311 secures the upper housing303 and the bottom housing 321 in place in the wellbore330.[0042] The high-pressure liquid pushes against theseal 309, expanding the expansion chamber 307 andpushing the mandrel 327 (downwardly in Fig. 4), whichresults in longitudinal movement of the tubing 302. Thisalso decreases the volume of a hydrostatic chamber325 the liquid escaping past the stop 315 into the well-bore 330, while increasing the volume of a sub-hydro-static chamber 326. The hydrostatic chamber 325 is de-fined by an outer surface of the mandrel 327 and an in-ner surface of sliphousing 314. The sub-hydrostaticchamber 326 is similarly defined. Movement of the man-drel 327 ceases when the seal 309 abuts a stop 315 onthe inner surface of the slip housing 314. When the tub-ing string ceases its motion, the pumping of fluid into thetubing is stopped and then the pressure in the expansionchamber 307 and in the slip set chamber 304 equalizewith the pressure in the wellbore 330. This allows thespring 306 to move the upper housing 303 away fromthe bottom housing 321, which results in the disengage-ment of the slips 311 from the wall 334 of the wellbore330.[0043] Fluid pressure in the sub-hydrostatic chamber326 is significantly less than (such as 5000 psi (34MPa)to 6000psi (41MPa) the hydrostatic pressure ) of fluid inthe wellbore 330, in the expansion and slip set cham-bers, and in a buffer chamber 319 below the sub-hydro-static chamber 326. This pressure differential causesthe sub-hydrostatic chamber 326 to contract along withthe expansion chamber 307 as the hydrostatic chamber325 expands. A spring 341 acts to dissipate the force ofundesired impacts on the system and/or on the payload324. As a result of these chamber expansions and con-tractions, the upper housing 303 and the bottom housing321 (with the slips disengaged from the wellbore) movedown with respect to the mandrel 327 until the spring341 is completely compressed.[0044] When the system 300 has moved, the surfacemud pump is again activated to set the slips and movethe mandrel to advance the tubing 302. A system suchas the system 300 may be activated and deactivated byan operator at the surface cycling a pump to pump fluid

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down to the system. In one aspect the system will be'on' for intervals of about 30 s, and 'off' for intervals ofabout 30 s. In some embodiments of this invention, it ispossible to cycle the system at intervals as long as 3minutes or as short as 30 s. It is within the scope of thisinvention to use two or more tractor systems connectedtogether so that the power strokes of the systems over-lap, providing continuous motion of the payload.[0045] Fig. 5 shows a wellbore tractor system 400 ofthe invention which provides near-continuous motion tomove an item through a wellbore 480.[0046] The system 400 has a mandrel 450 with twotractor elements, a lower (or front) tractor unit 422, andan upper (or rear) tractor unit 413. The mandrel 450 isconnected at one end to an item or string to be movedthrough a wellbore.[0047] The system 400 has two hydraulic circuits, apower-retract circuit for the two tractor units (includinglines 463, 468 and 418), and a control circuit (includinglines 464, 465, 467, 472, 407, 460 and 469 and valves405, 406, 410 and 420).[0048] Fluid for controlling the upper tractor unit flowsto and from a rear pilot control valve 405, and fluid forcontrolling the lower tractor unit flows to and from a frontpilot control valve 420. A pump 430 for the system maybe driven by a downhole motor or it may be electricallypowered and run on a cable. The pump 430 pumps fluidto and from a sump 431 and/or a sump 432.[0049] The upper tractor unit 413 has an arm mount481 to which is pivotably connected an end of a first arm482. The other end of the first arm 482 is pivotably con-nected to slip 483. The other end of the slip 483 is piv-otably connected to an arm mount 485. A slip set piston419 coacts with the arm mount 481. A seal 486 (suchas an O-ring seal) seals the mandrel/slip set piston in-terface at one end of the slip-set piston 419. The otherend of the slip-set piston 419 wraps over the outer endof the arm mount 481. An operating piston 417 is mov-ably disposed between the slip-set piston 419 and themandrel 450. A port 416 is located between an end ofthe operating piston 417 and the arm mount 485. A seal487 seals the operating piston/mandrel interfaces. Aseal 488 seals the arm mount/mandrel interface and thearm mount/slip-set piston interface. The mandrel hasexterior shoulders 490, 491, 492 and 493.[0050] A spring 494 urges a rear pilot control valve405 away from the shoulder 490. A spring 495 urges afront pilot control valve 420 away from the shoulder 492.A spring 496 urges the arm mounts 481 and 485 apart.Seals 497 seal the rear-pilot-valve/mandrel interface.Seals 498 seal the front-pilot-valve/mandrel interface.[0051] The lower tractor unit 422 has an arm mount501 to which is pivotably secured one end of an arm502. The other end of the arm 502 is pivotably securedto one end of a slip 503. The other end of the slip 503is pivotably secured to one end of an arm 504. The otherend of the arm 504 is pivotably secured to an arm mount505. One end of a slip-set piston 424 wraps over the

arm mount 505 and the other end of the slip-set pistonmoves along the mandrel 450. A seal 506 seals the slip-set-piston/mandrel interface at one end of the slip-setpiston 424. An operating piston 426 is movably disposedbetween the slip-set piston 424 and the mandrel 450. Aseal 507 seals the shoulder 493/operating-piston inter-face. A seal 508 seals the operating-piston/mandrel in-terface. A seal 509 seals the arm-mount/mandrel inter-face and the arm-mount/slip-set-piston interface.[0052] As shown in Figs. 5 and 6B, fluid under pres-sure through a line 468 enters an upper power chamber437. A portion of this fluid passes through a port 416,between the operating piston 417 and the slip-set piston419, to a chamber 439. As the chamber 439 expands,the upper end of the slip-set piston 419 pushes the arm482 and related apparatus so that the slips of the lowertractor unit 413 are moved out to engage the wellborewall. Simultaneously fluid under pressure in the upperpower chamber 437 acts on a shoulder 491, driving thesystem 400 (to the right in Fig. 5) and the item or stringattached to it further into the wellbore. Fluid in the re-traction chamber 447 escapes through line 471. Simul-taneously fluid under pressure in a line 418 from a valve406 enters a chamber 436 to retract the slips of the lowertractor unit 422. In Fig. 6B the upper tractor unit's powerstroke is nearly finished, and the retract stroke of thelower tractor unit is complete.[0053] The arm mount 481 pushes valve 405 so as tolink control lines 408 and 407 which shifts valve 410 (seeFig. 6C). A bleed valve 411 provides sufficient flow re-striction in the pilot control port to allow the valve 410 toshift. Hence fluid under pressure is directed through aline 468 from retract chamber 447 of the upper tractorunit 413 to sump 432 and from pump 430 to powerchamber 466. Retraction of the slips of the upper tractorunit 413 commences due to spring 496 forcing armmount 481 and arm mounted 485 apart and hence fluidfrom chamber 439 into the low pressure sump 432. Thechamber 466 of the lower tractor unit 422 begins filling,and the power stroke of the lower tractor unit 422 com-mences. At this time the lower tractor unit's retractchamber 436 is in fluid communication with a sump orreservoir 432 via line 418. The sumps 431 and 432 areindicated in two locations schematically, although onlyone sump may be used.[0054] As shown in Fig. 6B, fluid pressure in the powerchamber 437 of the upper tractor unit is greater than thatin the retract chamber 436 of the lower tractor unit, i.e.,so the power chamber receives fluid at a sufficiently-high pressure to move the mandrel 450, while a pres-sure-relief valve 406 controls pressure in the variouslines and ensures that pressure in the retract chamberis sufficient for retraction, but not greater than the pres-sure in the power chamber of the upper tractor unit.[0055] Preferably the dwell time between powerstrokes of the two tractor units, that is, the time requiredfor the valve 410 to switch power fluid from one tractor'spower chamber to the other chamber's power chamber,

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is at most 5% of the cycle time, more preferably at most2%, and most preferably 1%.[0056] As the system 400 moves the mandrel 450, theslip-set piston 501 compresses the spring 495 andmoves the pilot valve 420 so that fluid communicationcommences between lines 500 and 469. This permitsfluid to flow through the line 469 to operate valve 410,thereby shifting the lower tractor unit from a powerstroke to a retract stroke, and shifting the upper tractorunit from a retract stroke to a power stroke.[0057] Figs. 6A - 6D show the sequence of operationof the system 400. Fig. 6A shows the system as in Fig.5 for running a payload into a wellbore or tubular. In Fig.6B, the upper tractor unit 413 is in its power stroke, andthe lower tractor unit 422 is in its retract stroke. In Fig.6C, the upper tractor unit 413 is in its retract stroke andthe power stroke of the lower tractor unit 422 has begun.Fig. 6D is like Fig. 6B, but in Fig. 6D the upper unit hasjust reached the end of a power stroke and is switchingto a retract stroke, while the lower unit has just endedits retract stroke and is starting to set its slips. Hydraulicfluid pressure in all chambers of the tractor elements isequalized (to stop the tractor system with the slips onboth units retracted, such as in order to remove the trac-tor system from the wellbore) with the pressure of fluidin the wellbore 480, by means of the bleed valves 411and 412, through which fluid bleeds back to the sump432. Arrows on flow lines indicate flow direction.[0058] In Fig. 6B the upper tractor unit 413 has beenactivated so that its slip 483 is moved to engage the well-bore wall 484. The pump 430 provides hydraulic fluidunder pressure to the power chamber 437 and the rearoperating piston 417 through a line 415. The pilot-oper-ated directional valve 410 controls flow through the line415. The valve 410 is detented to provide a toggle actionbetween two control positions and, in the absence of pi-lot pressure through a line 472 or a line 469, remains inthe last position to which it is piloted. For start up, thevalve 410 can be in either position, since fluid will bedirected to a power piston of one of the tractor units, andeither lines indicate flow direction.[0059] Fluid pressure in the power chamber 437 high-er than the fluid pressure in the retract chamber 447forces the mandrel 450 to traverse down the borehole(see Fig. 6B). Fluid exhausted from the retract chamber447 is fed through a reducing/relieving valve 406 backto the sump 432.[0060] This cyclical motion is repeated as long as thepump 430 is producing fluid under pressure, causing thesystem to "walk" through or down the borehole. Whenthe pump 436 is stopped, the power lines 468 and 463to both power chambers bleed back to sump pressure.Spring loading of the slippers causes them to collapseback to the initial state, allowing the system to be re-trieved from the hole.[0061] There are three or four such units 413, 422spaced at 120° or 90° around the mandrel so that themandrel stays substantially central in the borehole.

[0062] Figs. 2 and 3A - 3E show a system 600 accord-ing to the present invention.[0063] The system 600 has a lower tractor unit 610,an upper tractor unit 620, and a central mandrel 653.The central mandrel 653 has in it a metre helical pas-sage 631, the power thread, at one pitch (e.g. about sixcomplete turns per metre) and a second helical passage632, the retract thread, at another pitch (e.g. about threecomplete turns per metre). A downhole motor 652 isconnected to the central mandrel 653 and is selectivelypowered from the surface to rotate the central mandrel653. There are two spaced-apart sets of oppositely-handed helical passages 631, 632.[0064] The system 600 provides continuous motionsince, due to the difference in pitch of the two passages631 and 632, the power stroke of each tractor unit duringwhich the system moves into the wellbore, is longer inlength than the return stroke. The return stroke is thepart of the power cycle of a tractor unit in which the trac-tor unit is not advancing the system along the wellbore,but is being moved with the system while the other trac-tor unit is anchored against the wellbore's interior.[0065] In a typical cycle of operation of the system600, motive fluid is pumped down tubing 651 from thesurface to power the mud motor 652. This rotates themud motor, which in turn rotates the central mandrel653. A passage follower 655 secured to the middlehousing 656 engages and rides in the passage (whichincludes the power thread handed in one direction andthe retract thread handed in the other direction) therebymoving a middle housing 656 (upwards in Fig. 2) in re-lation to an inner housing 657. This movement decreas-es the size of a power chamber 658, and fluid therein iscompressed. This fluid is transmitted through a port 659to a slip-set chamber 678. Introduction of the fluid intothe slip-set chamber 678 expands the chamber, result-ing in the movement of an outer housing 660 (upwardsin Fig. 2) over the middle housing 656, thereby settingslips 634.[0066] As the slip-setting continues, excess fluid inthe slip-set chamber 678 flows through a pressure reg-ulator valve port 663 into a reservoir chamber 662, thusmaintaining a constant pressure, slightly above the hy-drostatic pressure of fluid in the wellbore annulus andin the slip set chamber 678, keeping the slips 634 set.A compensating piston 664 maintains a constant hydro-static pressure (pressure level in the annulus betweenthe system's exterior and the wellbore's interior) in thereservoir chamber 662. A retaining collar 665 preventsthe compensating piston 664 from moving past the low-er end of the middle housing 656 and hydrostatic ports663 allow hydrostatic pressure from the wellbore to actbelow the compensating piston 664.[0067] The follower 655 in the passage 631 also pullsthe inner housing 657 through the middle housing 656and through the outer housing 660 through a centralizer667, thus moving the tubing 651 into the wellbore.[0068] At the end of the power stroke, the follower 655

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reaches the end of its passage 631, and shifts into theretract passage 632, reversing its longitudinal move-ment to begin a retract cycle. During the retract cycle ofone tractor unit, the fluid pressure in all the chambers ofthe unit returns to hydrostatic pressure via ports 659,663 and 666, allowing disengagement and unsetting ofthe slips. With the slips of the upper tractor unit disen-gaged, the middle housing 656 and outer housing 660are pulled downward relative to the inner housing 657by the lower tractor unit. At the end of the retract cycleof the upper unit, the follower 655 again enters the pow-er passage and reverses its longitudinal movement tocommence another power stroke of the upper unit.[0069] Since both the upper tractor unit 620 and thelower tractor unit 610 operate on the central mandrel653 with its interconnected power and retract passages,and each unit's power stroke is longer than its retractstroke, the power strokes will always overlap in time,and the system 600 will provide continuous motion. It isalways the case that, when one unit is in its retract strokethe other unit is in part of its power stroke. It is within thepurview of this invention for the helical passages andfollowers to be replaced by a helical screw-thread withappropriate grooved followers.[0070] Figs. 3A - 3E illustrate a typical cycle of the sys-tem 600. In Fig. 3A, the power stroke of the upper tractorunit 620 is ending and the retract stroke of the lowertractor unit 610 is ending. In Fig. 3B, the upper tractorunit's slips 634 have been disengaged, and the powerstroke of the lower tractor unit 610 is commencing. InFig. 3C, the retract stroke of the upper tractor unit 620is nearing an end and the power stroke of the lower trac-tor unit 610 is on-going. In Fig. 3D, the slips of the uppertractor unit 620 have been set, the power stroke of theupper tractor unit 620 has commenced, the powerstroke of the lower tractor unit 610 has ended and itsretract stroke is beginning. In Fig. 3E, the power strokeof the upper tractor unit 620 is nearing its end, and theretract stroke of the lower tractor unit 610 is on-going,with the slips of the lower tractor unit 610 disengaged.The lower unit 610 is like the upper unit 620.[0071] A tractor system according to the present in-vention may be run with a "full-bore" payload that has apath therethrough or thereon for conveying power fluidto the tractor system.[0072] In conclusion, therefore, it is seen that thepresent invention provides a wellbore tractor systemthat represents a significant technical advance overknown systems.

Claims

1. A wellbore tractor system (100, 600, 300, 400) formoving a component (101, 651, 302) along a well-bore or like passage (134, 334, 484) extending fromthe surface to an underground location, the systemcomprising:

a body (109, 657, 327, 450) connectable to thecomponent, the body having mounted on it an-choring means (123, 634, 311, 483) for selec-tively engaging the inner surface of the wellborein a releasable manner;means (190, 655, 309, 491) for moving thecomponent longitudinally relative to the anchor-ing means when engaged with the inner sur-face of the wellbore; andmeans (122, 632, 326, 447) for moving the an-choring means longitudinally with respect to thecomponent, in the direction of travel thereof, af-ter the anchoring means has been disengagedfrom the inner surface of the wellbore,

characterised in that said body is movablerelative to said anchoring means when engagedwith the inner surface of the wellbore to effect move-ment of said component along the wellbore, and inthat said anchoring means comprise slips.

2. A system as claimed in Claim 1, powered by an in-termittently-driven pump for supplying fluid underpressure to the interior of the body, the fluid beingvented into the wellbore, the cyclic and successiveanchoring and longitudinal movement phases beingeffected in accordance with the instantaneous pres-sure differential between the body interior and thewellbore.

3. A system as claimed in Claim 1, including a secondanchoring means (146, 610, 503) mounted on thebody at an axially-spaced location, the two anchor-ing means being adapted to be powered in alternat-ing anchoring and longitudinal movement phases,which phases overlap in time so that movement ofthe component is substantially continuous.

4. A system as claimed in any preceding claim, inwhich the or each anchoring means includes an ax-ially-movable sleeve (127, 660, 303, 417) of whichaxial movement relative to said body (109, 657,327, 450) effects radial movement of said anchoringmeans (123, 634, 311, 483).

5. A system as claimed in Claim 4, in which the relativeaxial movement of the sleeve is effected by hydrau-lic fluid of which the pressure is controlled, the fluidbeing supplied to the interior of the body via thecomponent from a surface-mounted pump.

6. A system as claimed in Claim 3, or Claim 3 and anyclaim dependent therefrom, in which the supply ofhydraulic fluid to the anchoring means is controlledby control valves (126, 405, 420) in the form of col-lars embracing the body and movable axially there-of to interconnect associated hydraulic fluid lines.

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7. A system as claimed in Claim 3, or Claim 3 and anyclaim dependent thereon, in which both anchoringmeans are powered by the rotary movement of acommon mandrel (653) having in it composite hel-ical passages (632, 654) of which the pitches of theoppositely-handed portions are different from eachother, each set of passages being engaged by a fol-lower (655) fast with one each of the anchoringmeans, the followers being engaged in differentparts of its respective set of passages, whereby ro-tation of the mandrel effects longitudinal movementof both the mandrel and the disengaged anchoringmeans, relative to the engaged anchoring means.

8. A system as claimed in any preceding claim, inwhich the body of the system is connected to a pay-load (158, 651, 324) for movement therewith.

9. A method of moving a payload which comprises thestep of using the system as claimed in any preced-ing claim to move said payload along a wellbore.

10. A method of moving a component along a wellboreor like passage extending from the surface to an un-derground location, which method comprises thesteps of:

(1) connecting a wellbore tractor comprising abody and first anchoring means mounted onsaid body, to a component and inserting saidwellbore tractor and component into a wellbore;(2) engaging the inner surface of said wellborewith said first anchoring means;(3) moving said component relative to said an-choring means when engaged with said innersurface;(4) releasing said first anchoring means fromsaid inner surface; and(5) advancing said first anchoring means in thedirection of travel of the component;

characterised in that said first anchoringmeans comprise slips and in that step (3) is by mov-ing said body relative to said first anchoring means.

11. A method as claimed in Claim 11, said wellbore trac-tor further comprising second anchoring means,said method further comprising the steps of:

(1) before or after said first anchoring meansare released from said inner surface, engagingsaid inner surface with said second anchoringmeans;(2) moving said body relative to said second an-choring means to advance said component;(3) releasing said second anchoring meansfrom said inner surface; and(4) advancing said second anchoring means

relative to said body in the direction of travel ofthe component;

wherein said second anchoring means com-prise slips and the method is such that step (1) isperformed so that movement of said componentthrough said wellbore is continuous or substantiallycontinuous.

12. A method as claimed in Claim 11, wherein step (1)comprises a dwell time of up to 5% of the cycle timeof the first and second anchoring means.

Patentansprüche

1. Bohrloch-Zugsystem (100, 600, 300, 400) zum Be-wegen einer Komponente (101, 651, 302) längs ei-nes Bohrlochs oder eines ähnlichen Durchlasses(134, 334, 484), der sich von der Oberfläche zu ei-ner unterirdischen Stelle erstreckt, wobei das Sy-stem umfaßt:

einen Körper (109, 657, 327, 450), der mit derKomponente verbunden werden kann und andem ein Verankerungsmittel (123, 634, 311,483) angebracht ist, das mit der inneren Ober-fläche des Bohrlochs in lösbarer Weise wahl-weise in Eingriff gelangen kann;Mittel (190, 655, 309, 491), die die Komponentein Längsrichtung relativ zu dem Verankerungs-mittel bewegen, wenn dieses mit der innerenOberfläche des Bohrlochs in Eingriff ist; undMittel (122, 632, 326, 447), die das Veranke-rungsmittel in Längsrichtung in bezug auf dieKomponente in Richtung ihrer Bahn bewegen,nachdem der Eingriff des Verankerungsmittelsmit der inneren Oberfläche des Bohrlochs ge-löst worden ist,

dadurch gekennzeichnet, daß der Körperrelativ zu dem Verankerungsmittel beweglich ist,wenn dieses mit der inneren Oberfläche des Bohr-lochs in Eingriff ist, um eine Bewegung der Kompo-nente längs des Bohrlochs auszuführen, und daßdas Verankerungsmittel Gleiter umfaßt.

2. System nach Anspruch 1, das von einer intermittie-rend angetriebenen Pumpe mit Leistung versorgtwird, um in den Innenraum des Körpers mit Druckbeaufschlagtes Fluid zu liefern, wobei das Fluid indas Bohrloch entleert wird, wobei die zyklischenund aufeinanderfolgenden Verankerungs- undLängsbewegungsphasen in Übereinstimmung mitdem momentanen Druckdifferential zwischen demInnenraum des Körpers und dem Bohrloch ausge-führt werden.

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3. System nach Anspruch 1, das ein zweites Veranke-rungsmittel (146, 640, 610, 503) umfaßt, das amKörper an einer axial beabstandeten Stelle ange-bracht ist, wobei die beiden Verankerungsmittel sobeschaffen sind, daß sie in abwechselnden Veran-kerungs- und Längsbewegungsphasen mit Lei-stung versorgt werden, wobei die Phasen zeitlichüberlappen, so daß die Bewegung der Komponenteim wesentlichen kontinuierlich ist.

4. System nach einem vorhergehenden Anspruch, beidem das oder jedes Verankerungsmittel eine axialbewegliche Hülse (127, 660, 303, 417) enthält, de-ren axiale Bewegung relativ zum Körper (109, 657,327, 450) eine radiale Bewegung des jeweiligenVerankerungsmittels (123, 634, 311, 483) bewirkt.

5. System nach Anspruch 4, bei dem die relative axia-le Bewegung der Hülse durch Hydraulikfluid bewirktwird, dessen Druck gesteuert wird, wobei das Fluiddem Innenraum des Körpers über die Komponentevon einer an der Oberfläche angebrachten Pumpezugeführt wird.

6. System nach Anspruch 3 oder nach Anspruch 3 undeinem hiervon abhängigen Anspruch, bei dem dieZufuhr von Hydraulikfluid zu den Verankerungsmit-teln durch Steuerventile (126, 405, 420) in Form vonden Körper umgebenden Kränzen, die hierzu axialbeweglich sind, um zugeordnete Hydraulikfluidlei-tungen miteinander zu verbinden, gesteuert wird.

7. System nach Anspruch 3 oder nach Anspruch 3 undeinem hiervon abhängigen Anspruch, bei dem bei-de Verankerungsmittel durch die Drehbewegung ei-nes gemeinsamen Dorns (653) mit Leistung ver-sorgt werden, wobei der Dorn in sich zusammenge-setzte schraubenlinienförmige Durchlässe (632,654) besitzt, deren Steigungen der entgegenge-setzten Abschnitte voneinander verschieden sind,wobei jede Gruppe von Durchlässen durch einenFolger (655) jeweils mit einem der Verankerungs-mittel in Eingriff ist, wobei die Folger in verschiede-nen Teilen ihrer jeweiligen Gruppe von Durchlässenin Eingriff sind, wobei die Drehung des Dorns eineLängsbewegung sowohl des Dorns als auch desnicht in Eingriff befindlichen Verankerungsmittels inbezug auf das in Eingriff befindliche Verankerungs-mittel bewirkt.

8. System nach einem vorhergehenden Anspruch, beidem der Körper des Systems mit einer Nutzlast(158, 651, 324) verbunden ist, um sich damit zu be-wegen.

9. Verfahren zum Bewegen einer Nutzlast, das denSchritt des Verwendens des Systems nach einemvorhergehenden Anspruch umfaßt, um die Nutzlast

längs eines Bohrlochs zu bewegen.

10. Verfahren zum Bewegen einer Komponente längseines Bohrlochs oder eines ähnlichen Durchlasses,der sich von der Oberfläche zu einer unterirdischenStelle erstreckt, wobei das Verfahren die folgendenSchritte umfaßt:

(1) Verbinden einer Bohrloch-Zugeinrichtung,die einen Körper und ein am Körper angebrach-tes erstes Verankerungsmittel umfaßt, mit einerKomponente und Einsetzen der Bohrloch-Zug-einrichtung und der Komponente in ein Bohr-loch;(2) Herstellen eines Eingriffs zwischen der in-neren Oberfläche des Bohrlochs und dem er-sten Verankerungsmittel;(3) Bewegen der Komponente relativ zu demVerankerungsmittel, wenn dieses mit der inne-ren Oberfläche in Eingriff ist;(4) Lösen des ersten Verankerungsmittels vonder inneren Oberfläche; und(5) Vorschieben des ersten Verankerungsmit-tels in Richtung der Bewegung der Komponen-te;

dadurch gekennzeichnet, daß das ersteVerankerungsmittel Gleiter umfaßt und daß derSchritt (3) durch Bewegen des Körpers relativ zudem ersten Verankerungsmittel ausgeführt wird.

11. Verfahren nach Anspruch 10, bei dem die Bohrloch-Zugeinrichtung ferner ein zweites Verankerungs-mittel umfaßt, wobei das Verfahren ferner die fol-genden Schritte umfaßt:

(1) Herstellen eines Eingriffs zwischen der in-neren Oberfläche und dem zweiten Veranke-rungsmittel, bevor oder nachdem der Eingriffdes ersten Verankerungsmittels mit der innerenOberfläche gelöst wird;(2) Bewegen des Körpers relativ zu dem zwei-ten Verankerungsmittel, um die Komponentevorwärtszuschieben;(3) Lösen des zweiten Verankerungsmittelsvon der inneren Oberfläche; und(4) Vorwärtsschieben des zweiten Veranke-rungsmittels relativ zu dem Körper in Richtungder Bewegung der Komponente;

wobei das zweite Verankerungsmittel Gleiter um-faßt und das Verfahren so beschaffen ist, daß derSchritt (1) in der Weise ausgeführt wird, daß die Be-wegung der Komponente durch das Bohrloch kon-tinuierlich oder im wesentlichen kontinuierlich ist.

12. Verfahren nach Anspruch 11, bei dem der Schritt(1) eine Stehzeit von bis zu 5% der Zykluszeit der

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ersten und zweiten Verankerungsmittel besitzt.

Revendications

1. Système de tracteur de sonde (100, 600, 300, 400)destiné à déplacer un composant (101, 651, 302)le long d'une sonde ou d'un passage équivalent(134, 334, 484) s'étendant depuis la surface versun emplacement souterrain, le systèmecomprenant :

un corps (109, 657, 327, 450) pouvant être reliéau composant, le corps ayant monté sur lui desmoyens de fixation (123, 634, 311, 483) desti-nés à mettre en prise de manière sélective lasurface intérieure de la sonde de manièredétachable ;des moyens (190, 655, 309, 491) destinés à dé-placer le composant de manière longitudinalepar rapport aux moyens de fixation lorsqu'ilssont en prise avec la surface intérieure de lasonde ; etdes moyens (122, 632, 326, 447) destinés à dé-placer les moyens de fixation de manière lon-gitudinale par rapport au composant, dans ladirection de cheminement de celui-ci, aprèsque les moyens de fixation ont été débrayés dela surface intérieure de la sonde,

caractérisé en ce que ledit corps est mobilepar rapport auxdits moyens de fixation lorsqu'il sonten prise avec la surface intérieure de la sonde afind'effectuer un mouvement dudit composant le longde la sonde et en ce que lesdits moyens de fixationcomprennent des glissements.

2. Système selon la revendication 1, alimenté par unepompe à commande intermittente destinée à intro-duire du fluide sous pression à l'intérieur du corps,le fluide étant déchargé dans la sonde, les phasescycliques successives de fixation et de mouvementlongitudinal étant effectuées selon le différentiel depression instantané entre l'intérieur du corps et lasonde.

3. Système selon la revendication 1, comprenant desdeuxièmes moyens de fixation (146, 610, 503) mon-tés sur le corps au niveau d'un emplacement espa-cé de manière axiale, les deux moyens de fixationétant adaptés pour être alimentés en phases defixation alternative et de mouvement longitudinal,lesquelles phases se chevauchent dans le tempsafin que le mouvement du composant soit sensible-ment continu.

4. Système selon l'une quelconque des revendica-tions précédentes, dans lequel les ou chaque

moyens de fixation comprennent un manchon mo-bile de manière axiale (127, 660, 303, 417) dont lemouvement axial par rapport audit corps (109, 657,327, 450) effectue un mouvement radial desditsmoyens de fixation (123, 634, 311, 483).

5. Système selon la revendication 4, dans lequel lemouvement axial du manchon est effectué par unfluide hydraulique dont la pression est commandée,le fluide étant introduit à l'intérieur du corps par l'in-termédiaire du composant depuis une pompe mon-tée sur la surface.

6. Système selon la revendication 3, ou la revendica-tion 3 et une revendication quelconque dépendantede celle-ci, dans lequel l'introduction du fluide hy-draulique vers les moyens de fixation est comman-dée par des vannes de régulation (126, 405, 420)sous la forme de bagues d'arrêt encerclant le corpset mobiles de manière axiale autour de celui-ci afind'interconnecter les conduites de fluide hydrauliqueassociées.

7. Système selon la revendication 3, ou la revendica-tion 3 et une revendication quelconque dépendantede celle-ci, dans lequel les deux moyens de fixationsont alimentés par le mouvement rotatif d'un man-drin commun (653) possédant en son intérieur despassages hélicoïdaux composites (632, 654) dontles pas des parties se faisant face sont différentsles uns des autres, chaque ensemble de passagesétant en prise par un fouloir (655) de manière rapideavec chacun des moyens de fixation, les fouloirsétant en prise dans différentes pièces de son en-semble respectif de passages, moyennant quoi larotation du mandrin effectue un mouvement longi-tudinal à la fois du mandrin et des moyens de fixa-tion débrayés, par rapport aux moyens de fixationen prise.

8. Système selon l'une quelconque des revendica-tions précédentes, dans lequel le corps du systèmeest relié à une charge utile (158, 651, 324) pour unmouvement avec celle-ci.

9. Procédé de déplacement d'une charge utile quiconsiste à utiliser le système tel que revendiquédans l'une quelconque des revendications précé-dentes afin de déplacer ladite charge utile le longd'une sonde.

10. Procédé de déplacement d'un composant le longd'une sonde ou d'un passage équivalent s'étendantdepuis la surface vers un emplacement souterrain,lequel procédé consiste à :

(1) relier un tracteur de sonde comprenant uncorps et des premiers des moyens de fixation

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montés sur ledit corps à un composant et insé-rer ledit tracteur de sonde et le composant àl'intérieur d'une sonde ;(2) mettre en prise la surface intérieure de la-dite sonde avec lesdits premiers moyens defixation ;(3) déplacer ledit composant par rapportauxdits moyens de fixation lorsqu'ils sont enprise avec ladite surface intérieure ;(4) libérer lesdits premiers moyens de fixationde ladite surface intérieure ; et(5) faire avancer lesdits premiers moyens defixation dans la direction de cheminement ducomposant ;

caractérisé en ce que lesdits premiersmoyens de fixation comprennent des glissementset en ce que l'étape (3) est réalisée par le déplace-ment dudit corps par rapport auxdits premiersmoyens de fixation.

11. Procédé selon la revendication 10, ledit tracteur desonde comprenant en outre des deuxièmesmoyens de fixation, ledit procédé consistant enoutre à :

(1) avant ou après que lesdits premiers moyensde fixation ont été libérés de ladite surface in-térieure, mettre en prise ladite surface intérieu-re avec lesdits deuxièmes moyens de fixation ;(2) déplacer ledit corps par rapport auxditsdeuxièmes moyens de fixation pour faire avan-cer ledit composant ;(3) libérer lesdits deuxièmes moyens de fixa-tion de ladite surface intérieure ; et(4) faire avancer lesdits deuxièmes moyens defixation par rapport audit corps dans la directionde cheminement du composant ;

dans lequel lesdits deuxièmes moyens defixation comprennent des glissements et le procédéest tel que l'étape (1) est exécutée afin que le mou-vement dudit composant à travers ladite sonde soitcontinu ou sensiblement continu.

12. Procédé selon la revendication 11, dans lequell'étape (1) comprend un temps de séjour représen-tant jusqu'à 5 % du temps de cycle des premiers etdes deuxièmes moyens de fixation.

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(12) NEW EUROPEAN PATENT SPECIFICATIONAfter opposition procedure

(45) Date of publication and mention of the opposition decision: 03.11.2010 Bulletin 2010/44

(45) Mention of the grant of the patent: 29.01.2003 Bulletin 2003/05

(21) Application number: 97932899.4

(22) Date of filing: 03.07.1997

(51) Int Cl.:E21B 23/00 (2006.01) E21B 23/04 (2006.01)

E21B 4/18 (2006.01)

(86) International application number: PCT/GB1997/001868

(87) International publication number: WO 1998/001651 (15.01.1998 Gazette 1998/02)

(54) WELLBORE TRACTOR

ZIEHVORRICHTUNG FÜR BOHRLÖCHER

TRACTEUR POUR FORAGE

(84) Designated Contracting States: DE DK GB NL

(30) Priority: 03.07.1996 US 675176

(43) Date of publication of application: 27.10.1999 Bulletin 1999/43

(73) Proprietor: Expro Americas, IncHouston, TX 77079 (US)

(72) Inventors: • NEWMAN, Kenneth, Ray

Willis, TX 77378-6625 (US)• HAVER, Nelson, Alan

Spring, TX 77389 (US)

• SPELLER, David, JosephHouston, TX 77095 (US)

(74) Representative: Lucas, Brian RonaldLucas & Co. 135 Westhall RoadWarlingham,Surrey CR6 9HJ (GB)

(56) References cited: EP-A- 0 149 528 WO-A-97/08418GB-A- 2 241 723 US-A- 3 180 437US-A- 3 661 205 US-A- 3 664 416US-A- 4 558 751

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Description

[0001] This invention relates to wellbore tractors and,in one particular aspect, to a tractor system useful in anon-vertical wellbore to move continuously a tubularstring, a wireline, a cable, or coiled tubing.[0002] In vertical wellbores and semi-vertical well-bores which are not highly deviated, wirelines, cable,coiled tubing, tubular strings and tools introduced intothe wellbore move down into the wellbore by the force ofgravity.[0003] Cable or wireline reaches a deviation threshold(e.g. for certain systems a deviation of about 70° fromthe vertical, e.g. wireline systems) at which gravity nolonger provides the necessary force and resulting tensionto move the cable or wireline down and through a well-bore.[0004] To a certain extent, tubular strings and coiledtubing can be pushed through a deviated wellbore, evenpart of a horizontally or upwardly-directed wellbore; butthere is a limit to the length of coiled tubing that can bepushed in this manner. When compressive loads in atubular string become large enough, the tubular stringforms a helical jam in the wellbore (cased or uncased),and further insertion movement is preheated. This isknown as "helical lockup."[0005] US-A-4 558 751 discloses an apparatus for pro-pelling equipment through a fluid filled conduit. The ap-paratus comprises two bodies which can engage the in-ner surface of the conduit, and a biasing element con-nected therebetween. The biasing element responds toa reduction and increase in fluid pressure within the con-duit by moving the two bodies toward and away from oneanother respectively. Thus, by selective engagementwith the inner surface, the apparatus can move throughthe conduit in an "inchworm" fashion. It will be noted thatwhen engaged with the inner surface each body is notmovable relative thereto.[0006] GB-A-2241723 discloses self-propelled appa-ratus designed to propel itself with sufficient traction soas to act as a tractor to tow. push or otherwise transportequipment along a tube, pipe or well. A main area ofapplication for the apparatus is in the mining and petro-leum industries. One form of the apparatus travels in acaterpillar-type way. In another form of the apparatusdriven wheels are biased into contact with the inside sur-face of a tube, pipe or well.[0007] With reference to WO 97/08418 the applicanthas voluntarily limited the scope of the present applica-tion for all designated countries, despite the fact that WO97/08418 is an intervening national right in the UK only.[0008] The present invention relates to a continuous,or nearly-continuous motion, wellbore tractor systemwhich has at least one slip unit (and in certain embodi-ments two slip units) with retractable slips for engagingan interior wall of casing or of a wellbore, and at leastone movement unit for moving an item such as, but notlimited to, a tubular string, cable, wireline, or coiled tubing

through a wellbore. In one aspect, while the slip unit orslip units are involved in engaging and disengaging froma wellbore, the movement unit(s) move the item. In oneaspect of such a system, with two slip units and two move-ment units, power strokes of the movement units overlap,so that there is no interruption in the motion of the item.[0009] It is, therefore, an object of the present inventionto provide wellbore tractor devices and methods of theiruse.[0010] Accordingly, the present invention provides amethod of pulling a component which is a tubular string,cable, wireline or coiled tubing along a wellbore or likepassage, said method having the features of claim 1 ofthe accompanying claims.[0011] In another aspect the invention provides a well-bore tractor system for use in the above mentioned meth-od, said system having the features of claim 4 of theaccompanying claims.[0012] A further aspect of the invention comprisesmoving a payload which comprises the step of using theabove mentioned system to move said payload along awellbore.[0013] Preferred features are set out in claims 2, 3 andclaims 5-10 of the accompanying claims.[0014] In one embodiment the present invention dis-closes a wellbore tractor system for moving an itemthrough a wellbore, the wellbore extending from earthsurface to an underground location, the system havinga body connected to the item, first setting means on thebody for selectively and releasably anchoring the systemin a wellbore, first movement means on the body for mov-ing the body and the item, the first movement meanshaving a first power stroke. The wellbore tractor has sec-ond setting means for selectively and releasably anchor-ing the system in the wellbore, the second setting meansbeing spaced apart from the first setting means, and sec-ond movement means on the body providing a secondpower stroke for moving the body and the item, the sec-ond movement means being spaced apart from the firstmovement means. In this a wellbore tractor system thefirst power stroke temporally overlaps the second powerstroke, so that the item is moved continuously.[0015] The item being moved into the wellbore may bea tubular string of interconnected tubular members or awireline. The wellbore tractor system of this inventionmay comprise first setting means including a selectively-movable first sleeve, and first slip means pivotably con-nected to the first sleeve for engaging an interior wall ofthe wellbore so that, upon movement of the first sleevein a first direction, the first slip means is moved into en-gagement with the interior wall and, upon movement ofthe first sleeve in a second direction the first slip meansis moved out of engagement with the interior wall. It mayalso comprise hydraulic apparatus for moving the selec-tively-movable first sleeve, the hydraulic apparatus beingpowered by fluid under pressure pumped into the hydrau-lic apparatus from the earth’s surface through the itembeing moved. The wellbore tractor system may comprise

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a selectively-movable second sleeve, and second slipmeans pivotably connected to the second sleeve for en-gaging an interior wall of the wellbore so that, upon move-ment of the second sleeve in a first direction, the secondslip means is moved into engagement with the interiorwall and, upon movement of the second sleeve in a sec-ond direction, the second slip means is moved out ofengagement with the interior wall.[0016] The present invention will now be described, byway of example, with reference to the accompanyingdrawings, in which:

Fig. 1A is a side view in cross-section of a wellboretractor system according to the present invention;Fig. 1B is an enlargement of a portion of the Systemof Fig. 1A;Fig. 1C1 and 1C2 is an enlargement of a portion ofthe system of Fig. 1A, and includes a schematic rep-resentation of an hydraulic circuit of the system;Fig. 2A is a side view in aross-seation of a secondembodiment of the present invention;Fig. 2B is an enlarged view of part of the system ofFig. 2A;Figs. 3A - 3B illustrate a sequence of operations ofthe system of Fig. 2;Fig. 4 is a side view in cross-section of a third em-bodiment of the present invention;Fig. 5 is a side view in cross-section of a fourth em-bodiment of the present invention; andFigs. 6A - 6D illustrate a sequence of operation ofthe system of Fig. 5.

[0017] As shown in Figs. 1A - 1C, a wellbore tractorsystem 100 according to the present invention has twotractor units, an upper unit 150 and a lower unit 160. Theupper half 150 has a mud motor 102 in fluid communi-cation with a wellbore tubing string 101 such as is typicallyinterconnected with a wellbore mud motor. An inflatablehydraulic fluid reservoir bladder 103 is disposed in achamber 151 in a housing 152. The mud motor 102 ispowered by pressurized fluid selectively suppliedthrough the tubing 101, into the housing 152, to the mudmotor 102. Fluid exhausts from the mud motor 102through ports 106 which are in fluid communication withan internal bore 118 through the system 100.[0018] The mud motor 102 powers a pump 107 whichpumps fluid under pressure from the bladder 103 in a line105 and then in a line 128 through an annulus 108 to thetractor units 150 and 160. The annuls 108 is between aninner housing 110 which is secured to a middle housing109, both of which are secured to the housing 152.The tractor units advance the middle housing 109 (andhence the tubing string 101) by pushing against shoul-ders projecting outwardly from the middle housing 109,an upper shoulder 189 in the upper unit 150 and a lowershoulder 190 in the lower unit 160. Hydraulic circuit pipingand other elements interconnecting the pump 107 andvarious tractor unit control valves and ports are located

within the annuls 108. By way of a port 104, the pressureof fluid in an annulus 153 between an inner wall 134 ofa wellbore 130 and an outer wall of the mud motor hous-ing 152 is applied to the bladder 103. In the hydrauliccircuit shown in Figs. 1B, 1C1 and 1C2, pump 107 pumpsfluid under pressure to a controls valve 161 and to a con-trol valve 125. The control valve 161 controls the lowerunit 160, and the control valve 125 and a second controlvalve 126 control the upper unit 150.[0019] A valve member 114 disposed around the mid-dle housing 109 has a body 154 with ribs 155, 156, 157which define a plurality of fluid communication chambers170, 171, 172, and 173. A sleeve 133 disposed aroundthe middle housing 109 is movable to move the valvemember 114 so that various ports are in fluid communi-cation via the communication chambers 170-173. Theseports include ports 111, 112, 113, 115, 116 and 117.[0020] Pivotably secured to the outer housing 127 is afirst slip arm 131, which is also pivotably secured at itsother end to a slip 123. A second slip arm 132 has a firstend pivotably secured to the slip 123, and a second endpivotably secured to the sleeve 133. As the outer housing127 moves up with respect to the sleeve 133 and withrespect to the middle housing 109, the slip arms 131, 132pivot to move the slip 123 of the upper unit 150 outwardlyto contact and engage the inner wall 134 of a wellbore130.[0021] The upper unit 150 has an outer housing 127which is movable with respect to the valve member 114and the middle housing 109. The lower unit 160 has asimilar outer housing 147, slip arms 148 and 149, andslip 146 which operate in a similar fashion.[0022] The sleeve 133 has an activating ring 122 hav-ing a shoulder 197 which upon contact moves a pivotarm 121 of the valve member 114, thereby moving thevalve member 114. A spring 120 biases the pivot arm121, and hence the valve member 114, initially down-wardly. An abutment surface 200 on the interior of thesleeves 133 is movable to contact valve stems 144 and178 of the control valves 125 and 126 respectively tomove and operate these control valves. O-rings 201 incorresponding recesses seal interfaces between variouselements.[0023] The control valve 125 is disposed in a chamberin the upper shoulder 189 of the middle housing 109 andhas a valve member 177 which is connected to the valvestem 178 and is movable to permit fluid flow betweenports 174 and 175 or between ports 175 and 176. Thecontrol valve 125 controls the fluid flow into a retractchamber 182 or a power chamber 183 of the upper unit150.[0024] The port 174 is in fluid communication with aflow line 192 to power chamber 183. The port 175 is influid communication with a flow line 139 which is in fluidcommunication with pump 107. The port 176 is in fluidcommunication with a flow line 191 which is connectedto a retract chamber 182.[0025] The control valve 126 is diametrically opposed

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to the control valve 125 and works simultaneously in tan-dem with it. The control valve 126 is also disposed in achamber in the upper shoulder 189 of the middle housing109 and has a valve member 140 which is connected tothe valve stem 144 and is movable to permit fluid flowbetween ports 141 and 142 or between ports 142 and143. The control valve 126 controls the flow of fluid fromthe retract chamber 182 or from the power chamber 183of the upper unit 150. The port 143 is in fluid communi-cation with a flow line 167 which is connected to the powerchamber 183. The port 142 is in fluid communication withflow line 135 which leads back to bladder 103. The port141 is in fluid communication with a flow line 166 whichis connected to the retract chamber 182.[0026] In a typical cycle of operation of the system 100,the system 100 connected to a tubular string 101 is in-troduced into the wellbore 130 and located at a desiredlocation therein, e.g. by the force of gravity on the system100. At that location, motive fluid under pressure is sup-plied down through the tubular string 101 to the mud mo-tor 102. The mud motor 102 drives the pump 107 whichin turn pumps fluid under pressure from the bladder 103,through the line 119, into the annular space 108 for pro-vision to the various valves that control the tractor units150 and 160.[0027] The pump 107 pumps hydraulic fluid underpressure into a line 199, to a line 138, to the port 112 andto line 139 to the port 175. With the valve member 114in the position shown in Fig. 1C, fluid flows from the port112, into the chamber 173, to the port 111, to a line 194,and down to the lower unit 160. The fluid flows into apower chamber 181 of the lower unit 160 and flows fromthe power chamber 181, through a port 187, into a cham-ber 186 setting the slip 146 of the lower unit. The fluid inthe chamber 181 then pushes on the lower shoulder 190and moves the middle housing 109 down. the fluid inchamber 180 escapes via line 195 through port 115 invalve member 114 and through port 116 to bladder 103.The sleeve 133 of the upper unit 150 simultaneouslymoves in a similar fashion by fluid entering port 175 vialine 139 into valve 161 which directs fluid into upper pow-er clamber 183 via line 192. The fluid in chamber 182escapes via line 166 into valve 140 and to bladder 103.[0028] The system 100/tubing 101 is moving down-wardly in the wellbore at this point in the cycle.[0029] As the sleeve 133 moves upwardly, the shoul-der 197 of the activating ring 122 contacts and then push-es on the pivot arm 121, compressing the spring 120,and moving the valve member 114 upwardly (as viewedin Fig. 1C).[0030] As the pivot arm 121 is moves toward a notch129, the valve member 114 move upwardly and fluid flowis stopped between the ports 111 and 112, cutting off theflow of fluid to the power chamber 181 of the lower unit160. At this point the power stroke of the lower unit 160ceases. While the activating ring 122 moves upwardlyover the pivot arm 121 in the notch 129, the valve member114 is prevented from moving downwardly, and fluid

flows through the port 112, through a chamber 172,through a port 113, to a line 195, to a retract chamber180 of the lower unit 160, and retraction commencing theretraction cycle.[0031] The size, length, disposition, and configurationof the activating ring 122 determine the length of timethat fluid flows from the power chamber 181 of the lowerunit 160. During this period, there is no fluid communi-cation between the ports 111 and 112. As the retractchamber 180 begins to fill with fluid under pressure andmove the sleeve 133 downwardly, fluid in the powerchamber 181 escapes through the line 194, to a line 137,to the port 117, to the chamber 170, to the port 116, tothe line 193, to the line 136, and back to the bladder 103.[0032] Once the activating ring 122 has moved up-wardly beyond the notch 129, the pivot arm 121 is freedand is pivoted outwardly by the spring 120, and the valvemember 114 is freed to move downwardly, again posi-tioning the chamber 173 so that fluid communication be-tween the ports 111 and 112 occurs. Fluid flows into thelower power chamber 181, and a new power stroke ofthe lower unit 160 commences. At every moment in thecycle, power is provided to move the tubular string 101by the upper unit 150, by the lower unit 160, or by both.[0033] The control valves 125 and 126 control the flowof fluid under pressure to and from the upper unit 150.When the sleeve 133 has moved upwardly to a sufficientextent, the abutment surface 200 contacts the valvestems 144 and 178. Subsequent movement of the valvemembers 140 and 177 results in fluid escaping from theupper power chamber 183 to bladder 103 via line 167and valve 126 and fluid into the upper retract chamber182 via line 191 and valve 125, shifting the upper unit150 from a power stroke to a retraction stroke.[0034] When the retraction stroke of the upper unit 150begins, the power stroke of the lower unit 160 is alreadyin progress (due to the timed and controlled introductionof fluid into the lower power chamber 181 as describedabove). When the retract stroke of the lower power unit160 begins, the power stroke of the upper unit 150 isalready in progress. Thus power is provided for the con-tinuous movement of the tubular string 101.[0035] When the sleeve 133 of the upper unit 150moves back downwardly, the valve stems 144 and 178contact an upper abutment surface 203 which shifts thevalve members 140 and 177 back to their initial positions(e.g. as in Fig. 1C) and a power stroke of the upper unit150 commences.[0036] A payload 158 such as logging tools, perforatingguns, sand clean-out equipment or any item run on theend of coiled tubing or on the end of a wireline) is con-nected to the bottom of the middle housing 109.[0037] Another embodiment of the invention is shownin Fig. 4, and is used to move a tubular string 302. Ofcourse this system may be used to move pipe, cable,casing, or coiled tubing. A payload 324 is connected toa lower end 328 of a hollow mandrel 327. An upper end329 of the mandrel 327 is connected to the tubing 302,

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and the bore 337 of the mandrel 327 is in fluid commu-nication with a flow bore 338 through the tubing 302.[0038] Fluid at relatively high pressure is pumpeddown the tubing 302 into the mandrel 327, such as froma surface mud pump which pumps high-pressure liquid,which enters the mandrel 327 and exits it through exhaustports 323 near the lower end 328. Preferably the liquidis at a sufficiently high pressure that the fluid pressurewithin the mandrel 327 is higher than the pressure of fluidin a wellbore 334 through which the system 300 extends.[0039] The high pressure liquid enters an expansionchamber through a port 308. The expansion chamber307 is defined by an exterior surface of the mandrel 327,an interior surface of a slip housing 314, and a mandrelseal 309. The fluid also enters a slip set chamber 304through a port 305 which is in fluid communication withthe expansion chamber 307. The slip set chamber 304is defined by an outer surface of the slip housing 314,and an inner surface of an upper housing 303.[0040] The increased pressure in the slip set chamber304 moves the upper housing 303 against a spring 306and toward a bottom housing 321. The spring 306 initiallyabuts an inner shoulder 335 on the upper housing 303and a lower outer shoulder 336 of the slip set housing314, and urges these two members apart. This move-ment of the upper housing 303 (down in a vertical well-bore, laterally in a horizontal wellbore, at a diagonal inan inclined wellbore) toward the lower housing 321 re-sults in the setting of slips 311 against an inner wall 334of the wellbore 330, setting the slips and catering thesystem 300 in the wellbore 330.[0041] Each slip 311 has one end pivotably connectedto a lower slip arm 312 which has a lower end pivotablyconnected to the slip housing 314, and its other end piv-otably connected to an upper slip arm 310 which has itsupper end pivotably connected to the upper housing 303.Setting of the slips 311 secures the upper housing 303and the bottom housing 321 in place in the wellbore 330.[0042] The high-pressure liquid pushes against theseal 309, expending the expansion chamber 307 andpushing the mandrel 327 (downwardly in Fig. 4), whichresults in longitudinal movement of the tubing 302. Thisalso decreases the volume of a hydrostatic chamber 325the liquid escaping past the stop 315 into the wellbore330, while increasing the volume of a sub-hydrostaticchamber 326. The hydrostatic chamber 325 is definedby an outer surface of the mandrel 327 and an inner sur-face of sliphousing 314. The sub-hydrostatic chamber326 is similarly defined. Movement of the mandrel 327ceases when the seal 309 abuts a stop 315 on the innersurface of the slip housing 314. When the tubing stringceases its motion, the pumping of fluid into the tubing isstopped and then the pressure in the expansion chamber307 and in the slip set chamber 304 equalize with thepressure in the wellbore 330. This allows the spring 306to move the upper housing 303 away from the bottomhousing 321, which results in the disengagement of theslips 311 from the wall 334 of the wellbore 330.

[0043] Fluid pressure in the sub-hydrostatic chamber326 is significantly less than (such as 5000 psi (34MPa)to 6000psi (41MPa) the hydrostatic pressure ) of fluid inthe wellbore 330, in the expansion and slip set chambers,and in a buffer chamber 319 below the sub-hydrostaticchamber 326. This pressure differential causes the sub-hydrostatic chamber 326 to contract along with the ex-pansion chamber 307 as the hydrostatic chamber 325expands. A spring 341 acts to dissipate the force of un-desired impacts on the system and/or on the payload324. As a result of these chamber expansions and con-tractions, the upper housing 303 and the bottom housing321 (with the slips disengaged from the wellbore) movedown with respect to the mandrel 327 until the spring 341is completely compressed.[0044] When the system 300 has moved, the surfacemud pump is again activated to set the slips and movethe mandrel to advance the tubing 302. A system suchas the system 300 may be activated and deactivated byan operator at the surface cycling a pump to pump fluiddown to the system. In one aspect the system will be ’on’for intervals of about 30 s, and ’off’ for intervals of about30 s. In some embodiments of this invention, it is possibleto cycle the system at intervals as long as 3 minutes oras short as 30 s. It is within the scope of this invention touse two or more tractor systems connected together sothat the power strokes of the systems overlap, providingcontinuous motion of the payload.[0045] Fig. 5 shows a wellbore tractor system 400 ofthe invention which provides near-continuous motion tomove an item through a wellbore 480.[0046] The system 400 has a mandrel 450 with twotractor elements, a lower (or front) tractor unit 422, andan upper (or rear) tractor unit 413. The mandrel 450 isconnected at one end to an item or string to be movedthrough a wellbore.[0047] The system 400 has two hydraulic circuits, apower-retract circuit for the two tractor units (includinglines 463, 468 and 418), and a control circuit (includinglines 464, 465, 467, 472, 407, 460 and 469 and valves405, 406, 410 and 420).[0048] Fluid for controlling the upper tractor unit flowsto and from a rear pilot control valve 405, and fluid forcontrolling the lower tractor unit flows to and from a frontpilot control valve 420. A pump 430 for the system maybe driven by a downhole motor or it may be electricallypowered and run on a cable. The pump 430 pumps fluidto and from a sump 431 and/or a sump 432.[0049] The upper tractor unit 413 has an arm mount481 to which is pivotably connected an end of a first arm482. The other end of the first arm 482 is pivotably con-nected to slip 483. The other end of the slip 483 is pivot-ably connected to an arm mount 485. A slip set piston419 coacts with the arm mount 481. A seal 486 (such asan O-ring seal) seals the mandrel/slip set piston interfaceat one end of the slip-set piston 419. The other end ofthe slip-set piston 419 wraps over the outer end of thearm mount 481. An operating piston 417 is movably dis-

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posed between the slip-set piston 419 and the mandrel450. A port 416 is located between an end of the operatingpiston 417 and the arm mount 485. A seal 487 seals theoperating piston/mandrel interfaces. A seal 488 seals thearm mount/mandrel interface and the arm mount/slip-setpiston interface. The mandrel has exterior shoulders 490,491, 492 and 493.[0050] A spring 494 urges a rear pilot control valve 405away from the shoulder 490. A spring 495 urges a frontpilot control valve 420 away from the shoulder 492. Aspring 496 urges the arm mounts 481 and 485 apart.Seals 497 seal the rear-pilot-valve/mandrel interface.Seals 498 seal the front-pilot-valve/mandrel interface.[0051] The lower tractor unit 422 has an arm mount501 to which is pivotably secured one end of an arm 502.The other end of the arm 502 is pivotably secured to oneend of a slip 503. The other end of the slip 503 is pivotablysecured to one end of an arm 504. The other end of thearm 504 is pivotably secured to an arm mount 505. Oneend of a slip-set piston 424 wraps over the arm mount505 and the other end of the slip-set piston moves alongthe mandrel 450. A seal 506 seals the slip-set-piston/mandrel interface at one end of the slip-set piston 424.An operating piston 426 is movably disposed betweenthe slip-set piston 424 and the mandrel 450. A seal 507seals the shoulder 493/operating-piston interface. A seal508 seals the operating-piston/mandrel interface. A seal509 seals the am-mount/mandrel interface and the arm-mount/slip-set-piston interface.[0052] As shown in Figs. 5 and 6B, fluid under pressurethrough a line 468 enters an upper power chamber 437.A portion of this fluid passes through a port 416, betweenthe operating piston 417 and the slip-set piston 419, toa chamber 439. As the chamber 439 expands, the upperend of the slip-set piston 419 pushes the arm 482 andrelated apparatus so that the slips of the lower tractorunit 413 are moved out to engage the wellbore will. Si-multaneously fluid under pressure in the upper powerchamber 437 acts on a shoulder 491, driving the system400 (to the right in Fig. 5) and the item or string attachedto it further into the wellbore. Fluid in the retraction cham-ber 447 escapes through line 471. Simultaneously fluidunder pressure in a line 418 from a valve 406 enters achamber 436 to retract the slips of the lower tractor unit422. In Fig. 6B the upper tractor unit’s power stroke isnearly finished, and the retract stroke of the lower tractorunit is complete.[0053] The arm mount 481 pushes valve 405 so as tolink control lines 408 and 407 which shifts valve 410 (seeFig. 6C). A bleed valve 411 provides sufficient flow re-striction in the pilot control port to allow the valve 410 toshift. Hence fluid under pressure is directed through aline 468 from retract chamber 447 of the upper tractorunit 413 to sump 432 and from pump 430 to power cham-ber 466. Retraction of the slips of the upper tractor unit413 commences due to spring 496 forcing arm mount481 and arm mounted 485 apart and hence fluid fromchamber 439 into the low pressure sump 432. The cham-

ber 466 of the lower tractor unit 422 begins filling, andthe power stroke of the lower tractor unit 422 commenc-es. At this time the lower tractor unit’s retract chamber436 is in fluid communication with a sump or reservoir432 via line 418. The sumps 431 and 432 are indicatedin two locations schematically, although only one sumpmay be used.[0054] As shown in Fig. 6B, fluid pressure in the powerchamber 437 of the upper tractor unit is greater than thatin the retract chamber 436 of the lower tractor unit, i.e.,so the power chamber receives fluid at a sufficiently-highpressure to move the mandrel 450, while a pressure-relief valve 406 controls pressure in the various lines andensures that pressure in the retract chamber is sufficientfor retraction, but not greater than the pressure in thepower chamber of the upper tractor unit.[0055] Preferably the dwell time between powerstrokes of the two tractor units, that is, the time requiredfor the valve 410 to switch power fluid from one tractor’spower chamber to the other chamber’s power chamber,is at most 5% of the cycle time, more preferably at most2%, and most preferably 1%.[0056] As the system 400 moves the mandrel 450, theslip-set piston 501 compresses the spring 495 and movesthe pilot valve 420 so that fluid communication commenc-es between lines 500 and 469. This permits fluid to flowthrough the line 469 to operate valve 410, thereby shiftingthe lower tractor unit from a power stroke to a retractstroke, and shifting the upper tractor unit from a retractstroke to a power strobe.[0057] Figs. 6A - 6D show the sequence of operationof the system 400. Fig. 6A shows the system as in Fig.5 for running a payload into a wellbore or tubular. In Fig.6B, the upper tractor unit 413 is in its power stroke, andthe lower tractor unit 422 is in its retract stroke. In Fig.6C, the upper tractor unit 413 is in its retract stroke andthe power stroke of the lower tractor unit 422 has begun.Fig. 6D is like Fig. 6B, but in Fig. 6D the upper unit hasjust reached the end of a power stroke and is switchingto a retract stroke, while the lower unit has just ended itsretract stroke and is starting to set its slips. Hydraulic fluidpressure in all chambers of the tractor elements is equal-ized (to stop the tractor system with the slips on bothunits retraced, such as in order to remove the tractorsystem from the wellbore) with the pressure of fluid inthe wellbore 480, by means of the bleed valves 411 and412, through which fluid bleeds back to the sump 432.Arrows on flow lines indicate flow direction.[0058] In Fig. 6B the upper tractor unit 413 has beenactivated so that its slip 483 is moved to engage the well-bore wall 484. The pump 430 provides hydraulic fluidunder pressure to the power chamber 437 and the rearoperating piston 417 through a line 415. The pilot-oper-ated directional valve 410 controls flow through the line415. The valve 410 is decanted to provide a toggle actionbetween two control positions and, in the absence of pilotpressure through a line 472 or a line 469, remains in thelast position to which it is piloted. For start up, the valve

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410 can be in either position, since fluid will be directedto a power piston of one of the tractor units, and eitherlines indicate flow direction.[0059] Fluid pressure in the power chamber 437 higherthan the fluid pressure in the retract chamber 447 forcesthe mandrel 450 to traverse down the borehole (see Fig.6B). Fluid exhausted from the retract chamber 447 is fedthrough a reducing/relieving valve 406 back to the sump432.[0060] This cyclical motion is repeated as long as thepump 430 is producing fluid under pressure, causing thesystem to "walk" through or down the borehole. Whenthe pump 436 is stopped, the power lines 468 and 463to both power chambers bleed back to sump pressure.Spring loading of the slippers causes them to collapseback to the initial state, allowing the system to be re-trieved from the hole.[0061] There are three or four such units 413, 422spaced at 120° or 90° around the mandrel so that themandrel stays substantially central in the borehole.[0062] Figs. 2 and 3A - 3E show a system 600 accord-ing to the present invention.[0063] The system 600 has a lower tractor unit 610,an upper tractor unit 620, and a central mandrel 653. Thecentral mandrel 653 has in it a metre helical passage631, the power thread, at one pitch (e.g. about six com-plete turns per metre) and a second helical passage 632,the retract thread, at another pitch (e.g. about three com-plete turns per metre). A downhole motor 652 is connect-ed to the central mandrel 653 and is selectively poweredfrom the surface to rotate the central mandrel 653. Thereare two spaced-apart sets of oppositely-handed helicalpassages 631, 632.[0064] The system 600 provides continuous motionsince, due to the difference in pitch of the two passages631 and 632, the power stroke of each tractor unit duringwhich the system moves into the wellbore, is longer inlength than the return stroke. The return stroke is the partof the power cycle of a tractor unit in which the tractorunit is not advancing the system along the wellbore, butis being moved with the system while the other tractorunit is anchored against the wellbore’s interior.[0065] In a typical cycle of operation of the system 600,motive fluid is pumped down tubing 651 from the surfaceto power the mud motor 652. This rotates the mud motor,which in turn rotates the central mandrel 653. A passagefollower 655 secured to the middle housing 656 engagesand rides in the passage (which includes the powerthread handed in one direction and the retract threadhanded in the other direction) thereby moving a middlehousing 656 (upwards in Fig. 2) in relation to an innerhousing 657. This movement decreases the size of apower chamber 658, and fluid therein is compressed.This fluid is transmitted through a port 659 to a slip-setchamber 678. Introduction of the fluid into the slip-setchamber 678 expands the chamber, resulting in themovement of an outer housing 660 (upwards in Fig. 2)over the middle housing 656, thereby setting slips 634.

[0066] As the slip-sotting continues, excess fluid in theslip-set chamber 678 flows through a pressure regulatorvalve port 663 into a reservoir chamber 662, thus main-taining a constant pressure, slightly above the hydrostaticpressure of fluid in the wellbore annulus and in the slipset chamber 678, keeping the slips 634 set. A compen-sating piston 664 maintains a constant hydrostatic pres-sure (pressure level in the annulus between the system’sexterior and the wellbore’s interior) in the reservoir cham-ber 662. A retaining collar 665 prevents the compensat-ing piston 664 from moving past the lower end of themiddle housing 656 and hydrostatic ports 663 allow hy-drostatic pressure from the wellbore to act below the com-pensating piston 664.[0067] The follower 655 in the passage 631 also pullsthe inner housing 657 through the middle housing 656and through the outer housing 660 though a centralizer667, thus moving the tubing 651 into the wellbore.[0068] At the end of the power stroke, the follower 655reaches the end of its passage 631, and shifts into theretract passage 632, reversing its longitudinal movementto begin a retract cycle. During the retract cycle of onetractor unit, the fluid pressure in all the chambers of theunit returns to hydrostatic pressure via ports 659, 663and 666, allowing disengagement and unsetting of theslips. With the slips of the upper tractor unit disengaged,the middle housing 656 and outer housing 660 are pulleddownward relative to the inner housing 657 by the lowertractor unit. At the end of the retract cycle of the upperunit, the follower 655 again enters the power passageand reverses its longitudinal movement to commenceanother power stroke of the upper unit.[0069] Since both the upper tractor unit 620 and thelower tractor unit 610 operate on the central mandrel 653with its interconnected power and retract passages, andeach unit’s power stroke is longer than its retract stroke,the power strokes will always overlap in time, and thesystem 600 will provide continuous motion. It is alwaysthe case that, when one unit is in its retract stroke theother unit is in part of its power stroke. It is within thepurview of this invention for the helical passages andfollowers to be replaced by a helical screw-thread withappropriate grooved followers.[0070] Figs. 3A - 3E illustrate a typical cycle of the sys-tem 600. In Fig. 3A, the power stroke of the upper tractorunit 620 is ending and the retract stroke of the lower trac-tor unit 610 is ending. In Fig. 3B, the upper tractor unit’sslips 634 have been disengaged, and the power strokeof the lower tractor unit 610 is commencing. In Fig. 3C,the retract stroke of the upper tractor unit 620 is nearingan end and the power stroke of the lower tractor unit 610is on-going. In Fig. 3D, the slips of the upper tractor unit620 have been set, the power stroke of the upper tractorunit 620 has commenced, the power stroke of the lowertractor unit 610 has ended and its retract stroke is begin-ning. In Fig. 3E, the power stroke of the upper tractor unit620 is nearing its end, and the retract stroke of the lowertractor unit 610 is on-going, with the slips of the lower

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tractor unit 610 disengaged. The lower unit 610 is likethe upper unit 620.[0071] A tractor system according to the present in-vention may be run with a "full-bore" payload that has apath therethrough or thereon for conveying power fluidto the tractor system.[0072] In conclusion, therefore, it is seen that thepresent invention provides a wellbore tractor system thatrepresents a significant technical advance over knownsystems.

Claims

1. A method of pulling a component (101, 651, 302)which is tubular string, cable, wireline or coiled tubingalong a wellbore or like passage (134, 334, 484) ex-tending from the surface to an underground locationdeviated from the vertical so that gravity no longerprovides the necessary force to move said compo-nent down and along said wellbore, which methodcomprises the steps of:

(1) connecting a wellbore tractor (100, 600, 300,400) comprising a body (109, 657, 327, 450) andfirst anchoring means (123, 634, 311, 483)mounted on said body, to said component andinserting said wellbore tractor and componentinto said wellbore;(2) engaging the inner surface of said wellborewith said first anchoring means;(3) moving said component relative to said firstanchoring means when engaged with said innersurface;(4) releasing said first anchoring means fromsaid inner surface; and(5) advancing said first anchoring means in thedirection of travel of the component;

characterised in thatsaid first anchoring means comprise slips eachmounted by a first arm pivoted at one end to a slipand its other end to an axially movable slip settingsleeve (127, 147; 620, 660; 303; 419,426) and by asecond arm pivoted at one end to said slip and at itsother end to a second sleeve (133, 233; 656; 314)on said body, axial movement of said slip settingsleeve relative to said body effecting radial move-ment of said slips, and in thatstep (3) is by moving the body relative to said firstanchoring means.

2. A method as claimed in claim 1, said wellbore tractorfurther comprising second anchoring means, saidmethod further comprising the steps of:

(1) before or after said first anchoring means arereleased from said inner surface, engaging said

inner surface with said second anchoringmeans;(2) moving said body relative to said second an-choring means to advance said component;(3) releasing said second anchoring means fromsaid inner surface; and(4) advancing said second anchoring means rel-ative to said body in the direction of travel of thecomponent;

wherein said second anchoring means compriseslips and the method is such that step (1) is per-formed so that movement of said component throughsaid wellbore is continuous or substantially continu-ous.

3. A method as claimed in Claim 2, wherein step (1)comprises a dwell time of up to 5% of the cycle timeof the first and second anchoring means.

4. A wellbore tractor system (100, 600, 300, 400) foruse in the method of claim 1, the system comprising:

a body (109, 657, 327, 450) connectable to acomponent, the body having mounted on it an-choring means (123, 634, 311, 483) for selec-tively engaging the inner surface of the wellborein a releasable manner;means (190, 655, 309, 491) for moving the com-ponent longitudinally relative to the anchoringmeans when engaged with the inner surface ofthe wellbore; andmeans (122, 632, 326, 447) for moving the an-choring means longitudinally with respect to thecomponent, in the direction of travel thereof, af-ter the anchoring means has been disengagedfrom the inner surface of the wellbore,characterised in that said body is movable rel-ative to said anchoring means when engagedwith the inner surface of the wellbore to effectmovement of said component along the well-bore, and in that said anchoring means com-prise slips each mounted by a first arm pivotedat one end to a slip and its other end to an axiallymovable slip setting sleeve (127, 147; 620, 660;303; 419,426) and by a second arm pivoted atone end to said slip and at its other end to asecond sleeve (133, 233; 656; 314) on saidbody, axial movement of said slip setting sleeverelative to said body effecting radial movementof said slips.

5. A system as claimed in claim 4, powered by an in-termittently-driven pump for supplying fluid underpressure to the interior of the body, the fluid beingvented into the wellbore, the cyclic and successiveanchoring and longitudinal movement phases beingeffected in accordance with the instantaneous pres-

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sure differential between the body interior and thewellbore.

6. A system as claimed in claim 5, including a secondanchoring means (146, 610, 503) mounted on thebody at a location axially spaced from said first an-choring means, the two anchoring means beingadapted to be powered in alternating anchoring andlongitudinal movement phases, which phases over-lap in time so that movement of the component issubstantially continuous.

7. A system as claimed in any of claims 4-6, in whichrelative axial movement of the sleeve is effected byhydraulic fluid of which the pressure is controlled,the fluid being supplied to the interior of the body viathe component from a surface-mounted pump.

8. A system as claimed in claim 6 or 7, in which thesupply of hydraulic fluid to the anchoring means iscontrolled by control valves (126, 405, 420) in theform of collars embracing the body and movable ax-ially thereof to interconnect associated hydraulic flu-id lines.

9. A system as claimed in claim 6, 7 or 8, in which bothanchoring means are powered by the rotary move-ment of a common mandrel (653) having in it com-posite helical passages (632, 654) of which the pitch-es of the oppositely-handed portions are differentfrom each other, each set of passages being en-gaged by a follower (655) fast with one each of theanchoring means, the followers being engaged indifferent parts of its respective set of passages,whereby rotation of the mandrel effects longitudinalmovement of both the mandrel and disengaged an-choring means, relative to the engaged anchoringmeans.

10. A system as claimed in any of claims 4-9, in whichthe body of the system is connected to a payload(158,651,324) for movement therewith.

11. A method of moving a payload which comprises thestep of using the system as claimed in claim 10 tomove said payload along a wellbore.

Patentansprüche

1. Verfahren zum Ziehen einer Komponente (101, 651,302), die ein rohrförmiger Strang, ein Seil, eineDrahtleitung oder eine Rohrwendel ist, längs einesBohrlochs oder eines ähnlichen Durchlasses (134,334, 484), das bzw. der sich von der Oberfläche zueinem unterirdischen Ort erstreckt, der von der Ver-tikalen abweicht, so dass die Schwerkraft nicht län-ger die notwendige Kraft bereitstellt, um die Kompo-

nente nach unten und längs des Bohrlochs zu be-wegen, wobei das Verfahren die folgenden Schritteumfasst:

(1) Verbinden einer Bohrlochzugeinrichtung(100, 600, 300, 400), die einen Körper (109, 657,327, 450) und erste Verankerungsmittel (123,634, 311, 483), die an dem Körper montiert sind,umfasst, mit der Komponente und Einsetzen derBohrlochzugeinrichtung und der Komponente indas Bohrloch;(2) Herstellen eines Eingriffs zwischen der inne-ren Oberfläche des Bohrlochs und den erstenVerankerungsmitteln;(3) Bewegen der Komponente relativ zu den er-sten Verankerungsmitteln, wenn diese mit derinneren Oberfläche in Eingriff sind;(4) Lösen der ersten Verankerungsmittel vonder inneren Oberfläche; und(5) Vorwärtsbewegen der ersten Verankerungs-mittel in Richtung der Bewegung der Kompo-nente;

dadurch gekennzeichnet, dassdie ersten Verankerungsmittel Gleiter umfassen,wovon jeder durch einen ersten Arm, der an einemEnde an einem Gleiter und an seinem anderen Endean einer axial beweglichen Gleitereinrichthülse (127,147; 620, 660; 303; 419, 426) angelenkt ist, unddurch einen zweiten Arm, der an einem Ende an demGleiter und an seinem anderen Ende an einer zwei-ten Hülse (133, 233; 656; 314) an dem Körper an-gelenkt ist, montiert ist, wobei eine axiale Bewegungder Gleitereinrichthülse in Bezug auf den Körper eineradiale Bewegung der Gleiter bewirkt, und dassder Schritt (3) durch Bewegen des Körpers relativzu den ersten Verankerungsmitteln ausgeführt wird.

2. Verfahren nach Anspruch 1, wobei die Bohrlochzug-einrichtung ferner zweite Verankerungsmittel um-fasst, wobei das Verfahren ferner die folgendenSchritte umfasst:

(1) bevor und nachdem die ersten Veranke-rungsmittel von der inneren Oberfläche gelöstwerden, Herstellen eines Eingriffs der innerenOberfläche mit den zweiten Verankerungsmit-teln;(2) Bewegen des Körpers relativ zu den zweitenVerankerungsmitteln, um die Komponente vor-wärts zu bewegen;(3) Lösen der zweiten Verankerungsmittel vonder inneren Oberfläche; und(4) Vorwärtsbewegen der zweiten Veranke-rungsmittel relativ zu dem Körper in Richtungder Bewegung der Komponente;

wobei die zweiten Verankerungsmittel Gleiter um-

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fassen und das Verfahren derart ist, dass der Schritt(1) so ausgeführt wird, dass eine Bewegung derKomponente durch das Bohrloch ununterbrochenoder im Wesentlichen ununterbrochen erfolgt.

3. Verfahren nach Anspruch 2, wobei der Schritt (1)eine Verweilzeit von bis zu 5 % der Zykluszeit derersten und der zweiten Verankerungsmittel enthält.

4. Bohrlochzugsystem (100, 600, 300, 400) für die Ver-wendung in dem Verfahren nach Anspruch 1, wobeidas System umfasst:

einen Körper (109, 657, 327, 450), der mit einerKomponente verbunden werden kann, wobei andem Körper Verankerungsmittel (123, 634, 311,483) montiert sind, um wahlweise einen Eingriffzwischen der inneren Oberfläche des Bohrlochsauf lösbare Weise herzustellen;Mittel (190, 655, 309, 491), um die Komponentein Längsrichtung relativ zu den Verankerungs-mitteln zu bewegen, wenn sie mit der innerenOberfläche des Bohrlochs in Eingriff sind; undMittel (122, 632, 326, 447), um die Veranke-rungsmittel in Längsrichtung in Bezug auf dieKomponente in Richtung ihrer Bewegung zu be-wegen, nachdem die Verankerungsmittel vonder inneren Oberfläche des Bohrlochs gelöstworden sind,dadurch gekennzeichnet, dass der Körper re-lativ zu den Verankerungsmitteln beweglich ist,wenn diese mit der inneren Oberfläche desBohrlochs in Eingriff sind, um eine Bewegungder Komponente längs des Bohrlochs zu bewir-ken, und dass die Verankerungsmittel Gleiterumfassen, wovon jeder durch einen ersten Arm,der an einem Ende an einem Gleiter und an sei-nem anderen Ende an einer axial beweglichenGleitereinrichthülse (127, 147; 620, 660; 303;419, 426) angelenkt ist, und durch einen zweitenArm, der an einem Ende an dem Gleiter und anseinem anderen Ende an einer zweiten Hülse(133, 233; 656; 314) angelenkt ist, am Körpermontiert ist, wobei eine axiale Bewegung derGleitereinrichthülse relativ zu dem Körper eineradiale Bewegung der Gleiter bewirkt.

5. System nach Anspruch 4, das durch eine intermit-tierend angetriebene Pumpe mit Leistung versorgtwird, um dem Innenraum des Körpers mit Druck be-aufschlagtes Fluid zuzuführen, wobei das Fluid indas Bohrloch entleert wird, wobei die zyklischen undaufeinander folgenden Verankerungs- und Längs-bewegungsphasen in Übereinstimmung mit der mo-mentanen Druckdifferenz zwischen dem Körperin-nenraum und dem Bohrloch ausgeführt werden.

6. System nach Anspruch 5, das zweite Verankerungs-

mittel (146, 610, 503) umfasst, die am Körper aneinem Ort montiert sind, der von den ersten Veran-kerungsmitteln axial beabstandet ist, wobei die zweiVerankerungsmittel dazu ausgelegt sind, in abwech-selnden Verankerungs- und Längsbewegungspha-sen mit Leistung versorgt zu werden, wobei die Pha-sen zeitlich überlappen, so dass eine Bewegung derKomponente im Wesentlichen ununterbrochen ist.

7. System nach einem der Ansprüche 4-6, wobei dierelative axiale Bewegung der Hülse durch Hydrau-likfluid, dessen Druck gesteuert wird, bewirkt wird,wobei das Fluid dem Innenraum des Körpers durchdie Komponente von einer oberirdisch montiertenPumpe zugeführt wird.

8. System nach Anspruch 6 oder 7, wobei die Zufuhrvon Hydraulikfluid zu den Verankerungsmittel durchSteuerventile (126, 405, 420) in Form von den Kör-per umgebenden Kränzen, die axial hierzu beweg-lich sind, um zugeordnete Hydraulikfluidleitungenmiteinander zu verbinden, gesteuert wird.

9. System nach Anspruch 6, 7 oder 8, wobei beide Ver-ankerungsmittel durch die Drehbewegung eines ge-meinsamen Dorns (653), in dem zusammengesetzteschraubenlinienförmige Durchlässe (632, 654) vor-handen sind, wobei Steigungen entgegengesetztorientierter Abschnitte hiervon voneinander ver-schieden sind, mit Leistung versorgt werden, wobeijeder Gruppe von Durchlässen mit einem Folger(655) in Eingriff ist, der an jeweils einem der Veran-kerungsmittel befestigt ist, wobei die Folger in ver-schiedenen Teilen ihrer jeweiligen Gruppe vonDurchlässen in Eingriff sind, wodurch eine Drehungdes Doms eine Längsbewegung sowohl des Domsals auch der nicht in Eingriff befindlichen Veranke-rungsmittel relativ zu den in Eingriff befindlichen Ver-ankerungsmitteln bewirkt.

10. System nach einem der Ansprüche 4-9, wobei derKörper des Systems mit einer Nutzlast (158, 651,324), die sich mit ihm bewegt, verbunden ist.

11. Verfahren zum Bewegen einer Nutzlast, das denSchritt des Verwendens des Systems nach An-spruch 10 umfasst, um die Nutzlast längs einesBohrlochs zu bewegen.

Revendications

1. Procédé consistant à tracter un composant (101,651, 302) qui est une rame tubulaire, un câble, uncâble de forage ou une colonne de production à tubespiralé le long d’un puits de forage ou d’un passageanalogue (134, 334, 484) s’étendant à partir de lasurface jusqu’à une position souterraine déviée par

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rapport à la verticale de telle sorte que la gravité nefournisse plus la force nécessaire pour déplacer leditcomposant vers le bas et le long dudit puits de fora-ge, lequel procédé comprend les étapes comportantle fait de :

1) raccorder un tracteur pour forage (100, 600,300, 400) comprenant un corps (109, 657, 327,450) et des premiers moyens d’ancrage (123,634, 311, 483) fixés sur ledit corps, au dit com-posant et insérer ledit tracteur pour forage etledit composant dans ledit puits de forage;2) engager la surface intérieure dudit puits deforage avec lesdits premiers moyensd’ancrage ;3) déplacer ledit composant par rapport aux ditspremiers moyens d’ancrage lorsque ceux-cisont engagés avec ladite surface intérieure ;4) libérer lesdits premiers moyens d’ancrage deladite surface intérieure ; et5) faire avancer lesdits premiers moyens d’an-crage dans la direction de circulation ducomposant ; caractérisé en ce que

lesdits premiers moyens d’ancrage comportent descales d’ancrage montées, chacune, par un premierbras pivotant au niveau d’une première extrémité surune cale d’ancrage et au niveau de son autre extré-mité à un manchon de positionnement de la caled’ancrage pouvant se déplacer axialement (127,147 ; 620, 660 ; 303 ; 419, 426) et par un secondbras pivotant au niveau d’une première extrémité surladite cale d’ancrage et au niveau de son autre ex-trémité à un second manchon (133, 233 ; 656 ; 314)situé sur ledit corps, le déplacement axial dudit man-chon de positionnement de la cale d’ancrage par rap-port au dit corps effectuant un déplacement radialdesdites cales d’ancrage, et en ce queune étape (3) consiste à déplacer le corps par rapportaux dits premiers moyens d’ancrage.

2. Procédé selon la revendication 1, ledit tracteur pourforage comprenant, de plus, des seconds moyensd’ancrage, ledit procédé comprenant, de plus, lesétapes comprenant le fait de,

(1) avant ou après que lesdits premiers moyensd’ancrage soient libérés à partir de ladite surfaceintérieure, engager ladite surface intérieureavec lesdits seconds moyens d’ancrage ;(2) déplacer ledit corps par rapport aux dits se-conds moyens d’ancrage afin de faire avancerledit composant ;(3) libérer lesdits seconds moyens d’ancrage deladite surface intérieure ; et(4) faire avancer lesdits seconds moyens d’an-crage par rapport au dit corps dans la directionde déplacement du composant ;

dans lequel lesdits seconds moyens d’ancrage com-prennent des cales d’ancrage et le procédé est telque l’étape (1) est exécutée de sorte que le dépla-cement dudit composant à travers le puits de foragesoit continu ou essentiellement continu.

3. Procédé selon la revendication 2, dans lequel l’étape(1) comporte un temps de maintien allant jusqu’à 5%de la durée du cycle des premiers et secondsmoyens d’ancrage.

4. Système de tracteur pour forage (100, 600, 300, 400)à utiliser dans le procédé selon la revendication 1,le système comprenant :

un corps (109, 657, 327, 450) pouvant être rac-cordé à un composant, le corps possédant,montés sur lui, des moyens d’ancrage (123, 364,311, 483) pour s’engager sélectivement avec lasurface intérieure du puits de forage d’une façonlibérable ;des moyens (190, 655, 309, 491) pour déplacerle composant longitudinalement par rapport auxmoyens d’ancrage lorsque ceux-ci sont enga-gés avec la surface intérieure du puits deforage ; etdes moyens (122, 632, 326, 447) pour déplacerles moyens d’ancrage longitudinalement parrapport au composant, dans la direction de sondéplacement, après que les moyens d’ancrageont été désengagés de la surface intérieure dupuits de forage,

caractérisé en ce que ledit corps peut se déplacerpar rapport aux dits moyens d’ancrage lorsque ceux-ci sont engagés avec la surface intérieure du puitsde forage afin d’effectuer un déplacement dudit com-posant le long du puits de forage, et en ce que lesditsmoyens d’ancrage comportent des cales d’ancragemontées, chacune, par un premier bras pivotant auniveau d’une première extrémité sur une cale d’an-crage et au niveau de son autre extrémité à un man-chon de positionnement de cale d’ancrage pouvantse déplacer axialement (127, 147 ; 620, 660 ; 303 ;419, 426) et par un second bras pivotant au niveaud’une première extrémité sur ladite cale d’ancrageet au niveau de son autre extrémité à un secondmanchon (133, 233 ; 656 ; 314) situé sur ledit corps,un déplacement axial dudit manchon de positionne-ment de cale d’ancrage par rapport au dit corps ef-fectuant le déplacement radial desdites cales d’an-crage.

5. Système selon la revendication 4, alimenté par unepompe entraînée de façon intermittente pour fournirun fluide sous pression à l’intérieur du corps, le fluideétant déchargé des gaz dans le puits de forage, lesphases de déplacement longitudinal et d’ancrage cy-

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clique et successives étant effectuées en fonctiondu différentiel de pression instantanée entre l’inté-rieur du corps et le puits de forage.

6. Système selon la revendication 5, comportant desseconds moyens d’ancrage (146, 610, 503) montéssur le corps au niveau d’une position espacée axia-lement desdits premiers moyens d’ancrage, les deuxmoyens d’ancrage étant adaptés pour être actionnésselon des phases de déplacement longitudinal etd’ancrage en alternance, lesquelles phases se che-vauchent dans le temps de sorte que le déplacementdu composant est essentiellement continu.

7. Système selon l’une quelconque des revendications4 à 6, dans lequel un déplacement axial relatif dumanchon est effectué par un fluide hydraulique dontla pression est commandée, le fluide étant fourni àl’intérieur du corps par l’intermédiaire du composantà partir d’une pompe montée en surface.

8. Système selon la revendication 6 ou 7, dans lequella fourniture du fluide hydraulique aux moyens d’an-crage est commandée par des vannes de comman-de (126, 405, 420) se présentant sous la forme decolliers entourant le corps et mobiles axialement parrapport à celui-ci afin d’interconnecter des lignes defluide hydraulique associées.

9. Système selon la revendication 6, 7 ou 8, dans lequelles deux moyens d’ancrage sont actionnés par lemouvement de rotation d’un mandrin commun (653)comportant en lui des passages hélicoïdaux compo-sites (632, 654) dont les pas des parties à pas op-posés sont différents l’un de l’autre, chaque ensem-ble de passages étant engagé par un suiveur (655)fixé à chacun des moyens d’ancrage, les suiveursétant engagés dans différentes parties de leur en-semble respectif de passages de sorte que la rota-tion du mandrin entraîne un déplacement longitudi-nal à la fois du mandrin et des moyens d’ancragedésengagés par rapport aux moyens d’ancrage en-gagés.

10. Système selon l’une quelconque des revendications4 à 9, dans lequel le corps du système est connectéà une charge utile (158, 651, 324) afin de se déplaceravec elle.

11. Procédé de déplacement d’une charge utile qui com-porte l’étape comprenant l’utilisation du système se-lon la revendication 10 afin de déplacer ladite chargeutile le long d’un puits de forage.

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21

EP 0 951 611 B2

22

EP 0 951 611 B2

23

EP 0 951 611 B2

24

EP 0 951 611 B2

25

REFERENCES CITED IN THE DESCRIPTION

This list of references cited by the applicant is for the reader’s convenience only. It does not form part of the Europeanpatent document. Even though great care has been taken in compiling the references, errors or omissions cannot beexcluded and the EPO disclaims all liability in this regard.

Patent documents cited in the description

• US 4558751 A [0005]• GB 2241723 A [0006]

• WO 9708418 A [0007]