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2 Stage and Liner Calculations

Module CF111 NL08 Sep 99

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What is Two Stage Cementing ?• The cementing of a string of casing in two stages !!

(Using a stage collar)

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What is Two Stage Cementing ?• The cementing of a string of casing in two stages !!

(Using a stage collar)

SECOND STAGE

FIRST STAGE

FLOAT COLLAR

FLOAT SHOE

STAGE COLLAR

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Why Two Stage Cementing ?• Reduce Hydrostatic

• Lost Circulation Zone or Low Frac Gradient

• Cement very long intervals (time / volume limitations)• TT or Logistics problem

• Reduce use of expensive slurries due to special well problems:

• Salt Zone

• Gas Zone

• Economy• Incomplete fill up

• Ensure part of annulus is free of cement

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Alternatives

• Use of lightweight slurries

– Foam Cement

– Litefil

This leads to:• Complex designs

• Logistical problems

• Expensive slurries

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Hardware

• What hardware is required that is different from a single stage cement job?

• Stage collar• Plugs

• First stage wiper plug• Opening plug/bomb• Closing plug

(a "Bottom" plug for the first stage is optional)

• Landing collar seal plate

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Stage Collar

Running in Position Running in Position

SHEAR PINS

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Stage Collar

Running in Position Running in Position Cementing Position Cementing Position

SHEAR PINS

OPENING

BOMB

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Stage Collar

Running in Position Running in Position Cementing Position Closed Position Cementing Position Closed Position

SHEAR PINS

OPENING

BOMB

OPENING

BOMB

CLOSINGPLUG

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Stage Collar Does Not Open !

• Possible Solutions :• Wait: Bomb may not have arrived yet.• Increase Pump Pressure.

• NOTE: Max P. or Burst P. of casing.

• Run D.P. in the hole and try to open mechanically (e.g. weight).

• Perforate above collar and cement.• NOTE: Might perforate through 2 casing.

No mechanical closing.

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Where to place 2 Stage Collar• Problem Formation

Lost circulation, Salt zone, etc.

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Where to place 2 Stage Collar• Problem Formation

Lost circulation, Salt zone, etc.

STAGE COLLAR

PROBLEM FORMATION

TOC

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Collar Inside Previous Casing

• Many clients insist on this .....

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Collar Inside Previous Casing

STAGE COLLAR• Many clients insist on this .....

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Collar Inside Previous Casing

STAGE COLLAR• Many clients insist on this .....

• Why ?To avoid “jetting” effect on the formation while circulating/cementingTo ensure that if the collar fails to open, at least the open hole section is

cemented

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“To WOC or not to WOC”...That is the Question

• Guideline:

• WOC: YES !..Height of the 2nd stage slurry may fracture the "problem formation"

• Otherwise - NO

• ALWAYS - Open collar immediately and circulate out excess cement.

• Note: Control circulating pressures, not to fracture any weak formations.

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2-Stage Casing to Wall PackersSTAGE COLLAR

CASING / WALL PACKER

• Purpose• To give an extra seal below the stage collar

• How do they function?• As the wiper plug (first stage) seals, pressuring up

shears some pins and displacement fluid is pumped into the packer, inflating it.

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Some Other Points

• The stage collar is eventually drilled out leaving the same "drift" as the rest of the casing.

• A stage collar is considered to be a "weak" point in the casing by many clients and so avoid using them.

• 3 Stage cementing is the same as 2 stage, but with 3 Stages.

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Job Procedure 2-Stage– Pressure test lines

– Pump wash/spacer

– Pump slurry

– Drop "First Stage" plug

– Displace: Bump Plug - Check Returns

– Drop Bomb - Wait Allocated Time

– Pressure Up to Open Stage Collar

– Circulate (W.O.C. if Required)

– Steps [2] and [3] Again - increase slurry density at the end

– Drop "Closing Plug"

– Displace - Close stage Collar

– Check Returns

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2-Stage Cementing Job - Example

13 3/8” 68 lb/ft Casing13 3/8” 68 lb/ft Casing

Top of cement at 2461 feetTop of cement at 2461 feet

13 3/8” shoe at 2789 feet13 3/8” shoe at 2789 feet

9 5/8” Stage collar at 4265.3 feet9 5/8” Stage collar at 4265.3 feet

12 1/4” O.H.12 1/4” O.H.

9 5/8” 53.50 lb/ft Casing9 5/8” 53.50 lb/ft Casing

9 5/8” Float collar at 6348.8 feet9 5/8” Float collar at 6348.8 feet

9 5/8” Shoe at 6398 feet9 5/8” Shoe at 6398 feet

44

33

1122

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2 Stage Cement Job - Answers

• First Stage Slurry Volume:[(6398-4265.3) x 0.3132] + [(6298-6348.8) x 0.3973]

= 687.5 ft3

• First Stage Displacement Volume:6348.8 x 0.0708 = 449.5 bbls

• Second Stage Slurry Volume:[(4265.3-2789) x 0.3132] + [(2789-2461) x 0.3354) = 572.4 ft3

• Second Stage Displacement Volume:4265.3 x 0.0708 = 302 bbls

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weak formation

weak formation

ProblemsPROBLEM 1:

Frac Gradient: 0.8 psi/ftMud: 12 ppg

salt zone salt zone

2400’

5500’

5850’

TD:8400’

4100’

7100 -7250FG: 0.6 psi/ft

TD:10200’

PROBLEM 2:

Frac Gradient: 0.8 psi/ftMud: 11.2 ppg

8400 - 8450FG:0.68 psi/ft

Answer the following:1. Would you recommend a 2-stage ? Why ?2. What depth would the Collar be?3. What is the maximum density of slurry possible during the first stage (assume cmt to stage collar)?4. Where would the TOC be for the first stage?

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Liners

• What is a Liner?

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Liners

LINERHANGER

CASINGSHOE

OVERLAP 50 - 500 FT

• Any string of casing whose top is located below the surface, hung inside the previous casing and is run to its setting depth by drill pipe.

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Why Liners ?• Prime reason:

• Save $$• (Cost of 1 Joint of Casing can be $3,000!)

• Cover Corroded/Damaged Casing• Cover:

• Lost Circulation Zones.• Shales or Plastic Formations• Salt Zones

• Deep Wells:• Rig Unable to Lift Long String of Casing.

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Types of Liners

• Production:• Most common• Save $$• Slotted liner

• Intermediate/drilling:• Cover problem zone in order to be able to continue

drilling

• Tie-back/liner complement:• From top of existing liner to surface, or further up casing

to cover corroded or damaged zone.

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Tie-Back (Liner Complement)The integration of the liner with casing run to surface

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Tie-Back (Liner Complement)The integration of the liner with casing run to surface

TIE BACKSTINGER WITHSEALS

LINER

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Tie-Back (Liner Complement)The integration of the liner with casing run to surface

TIE BACKSTINGER WITHSEALS

LINER

• This is often done if production is commercially viable or there is damage to casing above the liner

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Procedure for Setting Liner• RIH with drillpipe• At liner hanger depth, condition mud

– (Reciprocation / Rotation)

• Release slips (liner hanger)– (Rotation - mechanical pressure - hydraulic)

• Set slips, release liner weight, check to see if running tool is free• Pump mud - to ensure free circulation • Cement / Displace / Bump plug / Bleed off• Release setting tool• POOH above TOC and circulate• NOTE: A liner swivel can be run below the hanger to ensure that

the tool can be rotated even if the liner is stuck or set.

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Liner Overlap

• Cementing the liner “lap” is critical .

• Too much cement above the liner hanger is not recommended

• So make sure that “uncontaminated” cement is present at the liner lap - washes and spacers / WELLCLEAN

• If not, there is communication from the annulus to the formation

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Recommendations for Liner Cementing

• Ensure rheology of cement system is adequate for 100% mud removal

• Turbulent flow, if possible• Consider 5 - 10 min. “contact time” at liner lap• Batch mix cement• Minimize U-tubing effect• Rotation of liner during cementing (special bearing in

tool)• Adequate mud conditioning prior to cementing

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Job Procedure Liner• Pressure test lines.• Pump wash/spacer.• Pump slurry.• Drop "Pump Down" plug (or drill pipe wiper dart).• Displace

– To running tool

– Shear "Wiper Plug”

– Displace to Float Collar

• Bump plug/check for returns.• Release tool.• Pull up to T.O.C. and circulate.

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Liner example: WELL DATA1) Well Information:

– 9-5/8" 47 lb/ft intermediate casing surface to 6500’

– 7" 29 lb/ft intermediate liner 6200 ft to 10,500’

– 6" OH to TD at 14,500’

– DP 3-1/2" 13.30 lb/ft

– 4-1/2" 16.60 lb/ft liner required 14,400’ to 400’ inside 7" liner.

– FC 80’ above shoe.

2) Cement required to TOL with 20% excess in OH3) Calculate:

– Slurry and displacement volumes

– Job Procedure

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Liner example: WELL SCHEMATIC

3 1/2” drill pipe 13.3 lb/ft

9 5/8” casing shoe at 6,500 ft

9 5/8” casing 47 lb/ft

7” liner 29 lb/ft Top at 6,200 ft

7” liner shoe at 10,500 ft

4 1/2” liner 16.6 lb/ft top @ 10,100ft ; collar @ 14,320 ft

4 1/2” liner shoe at 14,400 ft

6” Open hole + 20% Excess

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LINER example: Calculations1) Slurry Volume:

• Volume #1 = 0.0981 ft3/ft x 400’ =39.2 ft3

• Volume #2 = 0.0859 ft3/ft x 3900’ x 1.2 = 402 ft3

• Volume #3 = 0.0769 ft3/ft x 80’ = 6.2 ft3

• Total Volume = + 80 bbls = 447.4 ft3

2) Displacement:• Drill Pipe = 0.00742 bbl/ft x 10,100’=74.9 bbls• Liner = 0.0137 bbl/ft x 4220’ = 57.8 bbls• Total Displacement = 132.7 bbls• Max. overdisplacement = (80 x 0.0137) / 2 = 0.55

bbls

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Liner example: Job Proc1) Mix Spacer and/or CW2) Pressure test lines;3) Batch Mix Cement Slurry;4) Pump Wash and/or Spacer;5) Pump 80 bbls of Slurry;6) Drop “Pump Down” plug;7) Displace with :

• + 74 bbls to the running tool and slow down flow rate to• Shear “Wiper Plug” @ + 75 bbls, then• RESET VOLUME and displace 57.8 bbls to Float Collar.

Maximum of 0.5 bbls over displacement if necessary.8) Bump plug / Bleed off / Check for returns;9) Release running tool;10) Pull out up to TOC and Reverse Circulate.

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HOMEWORK

Liner Cementing Calculations

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Handout

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