PhD meeting

Managed Pressure Drilling (MPD) Managed Pressure Drilling (MPD) in Floating Drilling Operationsin Floating Drilling Operations

Olve Sunde RasmussenOlve Sunde RasmussenOlve Sunde RasmussenOlve Sunde RasmussenNorwegian University of Science and Technology (NTNU)Norwegian University of Science and Technology (NTNU)

07-02-2008

Mud MarginMud Marginin Deep Water Reservoirsin Deep Water Reservoirs

Narrow poreNarrow pore-- and fracture gradientand fracture gradientNarrow poreNarrow pore and fracture gradient and fracture gradient marginmarginConsequences:Consequences:qq

Narrow mud weight windowNarrow mud weight window

More casing pointsMore casing points

Well control problemsWell control problems

Escalating total well costEscalating total well costEscalating total well costEscalating total well cost

MPD MethodsMPD MethodsMPD MethodsMPD MethodsMethods to keep well pressure constant through Methods to keep well pressure constant through th tith tithe operationthe operation

ConnectionsConnectionsTripping operationsTripping operationsTripping operationsTripping operationsVarying Varying flowrateflowrateVarying cuttings/gas content in mudVarying cuttings/gas content in mudVarying cuttings/gas content in mudVarying cuttings/gas content in mud

Single GradientSingle Gradient

Dual GradientDual Gradient

ChokeChoke

Choke + mud supplyChoke + mud supply

CCSCCS

SACSAC

Through Tubing Rotary Drilling (TTRD)Through Tubing Rotary Drilling (TTRD)Through Tubing Rotary Drilling (TTRD)Through Tubing Rotary Drilling (TTRD)

Sidetrack through Sidetrack through ggexisting completionexisting completionSmall annular clearanceSmall annular clearanceHigh ECDHigh ECDLarge Surge & Swab Large Surge & Swab pressures pressures MPD methods more MPD methods more attractiveattractiveattractiveattractive

Single Gradient MPD SystemsSingle Gradient MPD SystemsSingle Gradient MPD SystemsSingle Gradient MPD Systems

Dual Gradient MPD SystemsDual Gradient MPD Systemsyy

Moving interface betweenMoving interface betweenMoving interface between Moving interface between mud and seawatermud and seawaterSlower and less dramatic Slower and less dramatic pressure responsepressure response

Back Pressure Control MPD SystemsBack Pressure Control MPD SystemsBack Pressure Control MPD SystemsBack Pressure Control MPD Systems

Back Pressure Control MPD SystemsBack Pressure Control MPD SystemsBack Pressure Control MPD SystemsBack Pressure Control MPD Systems

Supplying mud throughSupplying mud throughSupplying mud through Supplying mud through separate conduit gives flexibilityseparate conduit gives flexibilityInjection points may be:Injection points may be:j p yj p y

Booster lineBooster lineUpstream of the choke manifoldUpstream of the choke manifoldKill / Choke lineKill / Choke line

Continuous Circulation MPD MethodsContinuous Circulation MPD MethodsContinuous Circulation MPD MethodsContinuous Circulation MPD Methods

Continuously circulate mud in the wellContinuously circulate mud in the wellContinuously circulate mud in the wellContinuously circulate mud in the wellCirculation not interrupted by connectionCirculation not interrupted by connection

Continuous CirculationContinuous CirculationSystem (CCS) MPDSystem (CCS) MPDSystem (CCS) MPDSystem (CCS) MPD

CirculateCirculate drillstringdrillstring duringduringCirculate Circulate drillstringdrillstring during during connectionsconnectionsCompensate by adjusting Compensate by adjusting p y j gp y j gpump speedpump speedPump rate may be limitedPump rate may be limitedp yp ySlower than normal Slower than normal connectionsconnections

Ref: Maris International

Secondary AnnulusSecondary AnnulusCi l ti (SAC) MPDCi l ti (SAC) MPDCirculation (SAC) MPDCirculation (SAC) MPD

Circulate down secondary annulusCirculate down secondary annulusCirculate down secondary annulus Circulate down secondary annulus during connectionduring connectionLarger pump rates may be availableLarger pump rates may be availableg p p yg p p yTripping out with Tripping out with drillstringdrillstring circulation circulation allows for faster tripping speedallows for faster tripping speedpp g ppp g p

Surge & SwabSurge & SwabAnnular Friction PressuresAnnular Friction Pressures

Tripping into / out of wellTripping into / out of wellTripping into / out of wellTripping into / out of wellFluid displaced by Fluid displaced by drillstringdrillstringFluid friction pressure dropFluid friction pressure dropp pp pSurge / Swab pressures ariseSurge / Swab pressures arise

May exceed poreMay exceed pore-- & fracture & fracture pressurespressuresTripping speed can be controlledTripping speed can be controlled

Drillpipe ConnectionDrillpipe ConnectionDrillpipe ConnectionDrillpipe Connection

Normally suspended fromNormally suspended fromNormally suspended from Normally suspended from compensated crowncompensated crownDrillstring suspended from Drillstring suspended from g pg protary tablerotary table (non(non--compensated)compensated)

Follows rig heave motion (Follows rig heave motion (ΔΔL)L)g (g ( ))Alternating Surge and Swab Alternating Surge and Swab effectseffects

Drillpipe ConnectionDrillpipe ConnectionDrillpipe ConnectionDrillpipe Connection

Heave motionHeave motionAmplitudeAmplitude

±±(m)(m)PeriodPeriod(sec)(sec)

Max VelocityMax Velocity±±(m/s)(m/s)

Surge/swabSurge/swabpressurespressures

(b )(b )Heave motionHeave motionAmplitudeAmplitudePeriodPeriod

(m)(m) (sec)(sec) (m/s)(m/s) ±±(bar)(bar)

0.50.5 1111 0.290.29 10.1810.18

1.01.0 1414 0.450.45 14.0014.00

Pipe speed not Pipe speed not operator operator

1.51.5 1111 0.860.86 24.3224.32

3.03.0 1313 1.451.45 55.6355.63

controllablecontrollable

ConclusionsConclusionsConclusionsConclusions

MPD methods may prove to be beneficial in a MPD methods may prove to be beneficial in a y py pnumber of casesnumber of cases

Deep waterDeep waterTTRDTTRDTTRDTTRDDepleted reservoirsDepleted reservoirs

Heave motions can cause surge and swabHeave motions can cause surge and swabHeave motions can cause surge and swab Heave motions can cause surge and swab pressures during pipe connectionspressures during pipe connections