Cálculos de cementación en una etapa
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Transcript of Cálculos de cementación en una etapa
Single Stage Calculations
2 Single Stage Cementing
Engineer’s Handbook
1 foot
1. OD2. LBS/FT3. CUFT/FT4. Displacement BBL/FT
3 Single Stage Cementing
Engineer’s Handbook
1 foot
1 foot
1. OD2. LBS/FT3. CUFT/FT4. Displacement BBL/FT
1. OD outside casing2. LBS/FT outside casing3. OD inside casing4. CUFT/FT
4 Single Stage Cementing
Engineer’s Handbook
1 foot
1 foot
1 foot
1. OD2. LBS/FT3. CUFT/FT4. Displacement BBL/FT
1. OD outside casing2. LBS/FT outside casing3. OD inside casing4. CUFT/FT
1. OD casing2. OH diameter3. CUFT/FT
5 Single Stage Cementing
Volumes to be Calculated : Step A
Open Hole
PreviousCasing
CollarShoe
3
11. Casing in casing
6 Single Stage Cementing
Volumes to be Calculated : Step A
Open Hole
PreviousCasing
CollarShoe
2
3
11. Casing in casing
2. Casing in open hole
7 Single Stage Cementing
Volumes to be Calculated : Step A
Open Hole
PreviousCasing
CollarShoe
2
3
1
3
1. Casing in casing
2. Casing in open hole
3. Inside casing(between collar and shoe)
8 Single Stage Cementing
Cement Calculations
Volume of open hole below the casing shoe is not calculated.Cement circulates out of the shoe and up the annulus.Any cement displacing the mud below by gravity is considered negligible.
9 Single Stage Cementing
Problem 1
Casing : 7” - 32 LB/FtShoe : 4600’Collar : 4510’Previous casing : 9 5/8 - 47 LB/FtShoe : 2670’Open hole : 8.5”Top of cement : 1000’Calculate Total Amount of Slurry Required in CuFt
10 Single Stage Cementing
SolutionCapacities
1. Cas-Cas - 0.1438 cuft/ft
2. Cas - OH - 0.1268 cuft/ft
3. Cas - 0.2025 cuft/ft, 0.0361 bbl/ft
Volumes
1000ft
2670ft
4510ft
4600ft
2
33
1
11 Single Stage Cementing
SolutionCapacities
1. Cas-Cas - 0.1438 cuft/ft
2. Cas - OH - 0.1268 cuft/ft
3. Cas - 0.2025 cuft/ft, 0.0361 bbl/ft
Volumes
1. (2670ft - 1000ft) x 0.1438 cuft/ft = 240.2 cuft
1000ft
2670ft
4510ft
4600ft
2
33
1
12 Single Stage Cementing
SolutionCapacities
1. Cas-Cas - 0.1438 cuft/ft
2. Cas - OH - 0.1268 cuft/ft
3. Cas - 0.2025 cuft/ft, 0.0361 bbl/ft
Volumes
1. (2670ft - 1000ft) x 0.1438 cuft/ft = 240.2 cuft
2. (4600ft - 2670ft) x 0.1268 cuft/ft = 244.7 cuft
1000ft
2670ft
4510ft
4600ft
2
33
1
13 Single Stage Cementing
SolutionCapacities
1. Cas-Cas - 0.1438 cuft/ft
2. Cas - OH - 0.1268 cuft/ft
3. Cas - 0.2025 cuft/ft, 0.0361 bbl/ft
Volumes
1. (2670ft - 1000ft) x 0.1438 cuft/ft = 240.2 cuft
2. (4600ft - 2670ft) x 0.1268 cuft/ft = 244.7 cuft
3. (4600ft - 4510ft) x 0.2025 cuft/ft = 18.2 cuft
1000ft
2670ft
4510ft
4600ft
2
33
1
14 Single Stage Cementing
SolutionCapacities
1. Cas-Cas - 0.1438 cuft/ft
2. Cas - OH - 0.1268 cuft/ft
3. Cas - 0.2025 cuft/ft, 0.0361 bbl/ft
Volumes
1. (2670ft - 1000ft) x 0.1438 cuft/ft = 240.2 cuft
2. (4600ft - 2670ft) x 0.1268 cuft/ft = 244.7 cuft
3. (4600ft - 4510ft) x 0.2025 cuft/ft = 18.2 cuft
TOTAL VOLUME = 503.1 CUFT
1000ft
2670ft
4510ft
4600ft
2
33
1
15 Single Stage Cementing
Excess
OnlyHere
Excess in only calculated on AnnularVolume in THE OPEN HOLE
16 Single Stage Cementing
Example: Problem 1
OH 50% Excess
OH volume (2) of the previous problem: 244.7cuft
Excess Volume: 244.7 cuft x 50/100 = 122.35 cuft
Total OH Volume: 367.05 cuft
OR 244.7 cuft x 1.50 = 367.05 cuft
17 Single Stage Cementing
Slurry Yield - Step B
The volume of slurry produced when one sack of cement ismixed with water is called
YIELD
18 Single Stage Cementing
Slurry Yield - Step BThe volume of slurry produced when one sack of cement is
mixed with water is calledYIELD
+CEMENTCEMENT
19 Single Stage Cementing
Slurry Yield - Step BThe volume of slurry produced when one sack of cement isThe volume of slurry produced when one sack of cement is
mixed with water is calledmixed with water is calledYIELDYIELD
WATER =+CEMENTCEMENT
20 Single Stage Cementing
Slurry Yield - Step BThe volume of slurry produced when one sack of cement isThe volume of slurry produced when one sack of cement is
mixed with water is calledmixed with water is calledYIELDYIELD
WATER =
The unit of slurry yield isThe unit of slurry yield is cuftcuft/sack/sack
+CEMENTCEMENT SLURRYSLURRY
21 Single Stage Cementing
Note:
1 sack of cementof 94 lbs = 1= 1 cuftcuft
4.97 gals of water = 0.66= 0.66 cuftcuft
22 Single Stage Cementing
Note:
1 sack of cement1 sack of cementof 94 lbsof 94 lbs = 1= 1 cuftcuft
4.97 gals of water4.97 gals of water = 0.66= 0.66 cuftcuft
11 cuftcuft + 0.66+ 0.66 cuftcuft = 1.66= 1.66 cuftcuft
23 Single Stage Cementing
Note:
1 sack of cement1 sack of cementof 94 lbsof 94 lbs = 1= 1 cuftcuft
But the But the Handbook states:Handbook states:
4.97 gals of water4.97 gals of water 1.151.15 cuftcuft/sack/sack= 0.66= 0.66 cuftcuft
WHY ?WHY ?11 cuftcuft + 0.66+ 0.66 cuftcuft = 1.66= 1.66 cuftcuft
24 Single Stage Cementing
Bulk volume vs Absolute volume
One drum full One drum full of dry cementof dry cement(1 drum = 1(1 drum = 1 cuftcuft))
Same size drumSame size drum0.66 of water0.66 of water
25 Single Stage Cementing
Bulk volume vs Absolute volume
One drum full One drum full of dry cementof dry cement(1 drum = 1(1 drum = 1 cuftcuft))
Pour waterPour waterinto cement
Same size drumSame size drum0.66 of water0.66 of water
into cement
Air in pore spaces willbe displaced by water
26 Single Stage Cementing
Note………
Yield varies with densityBasically, when you change the density you alter the
Water / Cement ratio....this changes the yield
Normally ........as you increase the water content the yield increases
27 Single Stage Cementing
BentoniteAPI States:
Ideal Mix (15.8 ppg) Lightweight Slurry (12.8) ppg
Cement Water
1 cu/ft 4.97 gals
Bentonite
12% ExtraBWOC Water
1 cu/ft 4.97 gals
Cement Water
1.15 cuft/sack
28 Single Stage Cementing
BentoniteAPI States:
Ideal Mix (15.8 ppg) Lightweight Slurry (12.8) ppg
Cement Water
1 cu/ft 4.97 gals
Bentonite 7.18 gals
12% ExtraBWOC Water
1 cu/ft 4.97 gals
Cement Water
1.15 cuft/sack
Only 4.97 gals water is required for the cement.A chemical has to be added to react with the extra water.
29 Single Stage Cementing
BentoniteBentonite is used in large quantities in oilfield slurries.As much as 25% BWOC is possibleOffshore this presents a problem due to limited storage capacities and dry blending facilities.If Bentonite is mixed with fresh mix water instead of being dry blended only 1/4 of the amount is needed
This is called: PREHYDRATED BENTONITEExample : Dry In Mix Water
2%BWOC 0.5%BWOC4%BWOC 1% BWOC
10%BWOC 2.5%BWOC
30 Single Stage Cementing
Handbook Gives:Ref
Class “G” Neat - Density 15.8 lbs/gals Yield = 1.15 cuft/sack 700.06
Water 4.97 gals/sack
Ref
Class “G” + 6% D20 - Density 13.9 lbs/gals Yield = 1.655 cuft/sack 700.013
Water 8.56 gal/sx
31 Single Stage Cementing
Step C - Cement Calculations
If you know what volume of slurry a sack of cement [YIELD] produces at a certain weight, you can calculate the amount of sacks required when you know a volume.
32 Single Stage Cementing
Step C - Cement Calculations
If you know what volume of slurry a sack of cement [YIELD] produces at a certain weight, you can calculate the amount of sacks required when you know a volume.
VOLUME[cuft]YIELD [cuft/sacks]
= Sacks
33 Single Stage Cementing
Example: Problem 1 (Continued)
Previous Problem:Lead volume [1] : 240.2 cuft Tail volume [2 + 3] :
367.05 cuft+ 18.2 cuft385.35 cuft
34 Single Stage Cementing
Example: Problem 1 (Continued)Previous Problem:Lead volume [1] : 240.2 cuft Tail volume [2 + 3] :
367.05 cuft+ 18.2 cuft385.35 cuft
Use:Lead Slurry : Class G + 6% D20 at 13.9 ppgTail Slurry Neat : Class G at 15.8 ppg
Cement volume Lead:
35 Single Stage Cementing
Example: Problem 1 (Continued)Previous Problem:Lead volume [1] : 240.2 cuft Tail volume [2 + 3] :
367.05 cuft+ 18.2 cuft385.35 cuft
Use:Lead Slurry : 6% D20 at 13.9 ppgTail Slurry Neat : 15.8 ppgCement volume Lead:
240.2 cuft = 145.2 sacks
1.655 cuft/sack
Cement volume Tail:
36 Single Stage Cementing
Example: Problem 1 (Continued)Previous Problem:Lead volume [1] : 240.2 cuft Tail volume [2 + 3] : 367.05 cuft
+ 18.2 cuft385.35 cuft
Use:Lead Slurry : 6% D20 at 13.9 ppgTail Slurry Neat : 15.8 ppgCement volume Lead:
240.2 cuft = 145.2 sacks1.655 cuft/sack
385.25 cuft = 335.0 sacks1.15 cuft/sack
Cement volume Tail:
37 Single Stage Cementing
Mix Water - Step D
If you know the number of sacks then you find the gal/sk of mix water required and multiplyMix Fluid = gal/sack x number of sacks
CONVERT TO BBLS
(Your displacement tanks are in bbls)
38 Single Stage Cementing
Mix Water Quality
In the laboratory, clean location water is used for cement test. Test results are only obtainable in the field when same water (= clean) is used.Causes for contamination:– Dirty rig tanks– Left over chemicals/mud in lines and pumps– Dirty displacement tanks
39 Single Stage Cementing
Total Water Available 1. Calculated mix water for cement + 20% safety+2. Water (ahead, behind, CW, spacer)+20 bbls minimum (priming and washing up)= TOTAL WATER NEEDED
40 Single Stage Cementing
Example: Problem 1 (Continued)Lead mix water 145sx x 8.56 gal/sx
41 Single Stage Cementing
Example: Problem 1 (Continued)Lead mix water 145sx x 8.56 gal/sx = 1241.2 gal
= 29.55 bbls
42 gal/bbl
42 Single Stage Cementing
Example: Problem 1 (Continued)
Lead mix water 145sx x 8.56 gal/sx = 1241.2 gal= 29.55 bbls
42 gal/bbl
Tail mix water 335sx x 4.97 ga/sx
43 Single Stage Cementing
Example: Problem 1 (Continued)Lead mix water 145sx x 8.56 gal/sx = 1241.2 gal
= 29.55 bbls
42 gal/bbl
Tail mix water 335sx x 4.97 ga/sx = 1664.95 gal = 39.64 bbls
42 gal/bbl
44 Single Stage Cementing
Example: Problem 1 (Continued)Lead mix water 145sx x 8.56 gal/sx = 1241.2 gal = 29.55 bbls
42 gal/bbl
Tail mix water 335sx x 4.97 ga/sx = 1664.95 gal = 39.64 bbls
42 gal/bbl
Total mix water 69.19 bbls
45 Single Stage Cementing
Example: Problem 1 (Continued)Lead mix water 145sx x 8.56 gal/sx = 1241.2 gal = 29.55 bbls
42 gal/bbl
Tail mix water 335sx x 4.97 ga/sx = 1664.95 gal = 39.64 bbls
42 gal/bbl
Total mix water 69.19 bbls
20% safety margin : 66.19 bbl x 20/100 = 13.84 bbls
46 Single Stage Cementing
Example: Problem 1 (Continued)Lead mix water 145sx x 8.56 gal/sx = 1241.2 gal = 29.55 bbls
42 gal/bbl
Tail mix water 335sx x 4.97 ga/sx = 1664.95 gal = 39.64 bbls
42 gal/bbl
Total mix water 69.19 bbls
20% safety margin : 66.19 bbl x 20/100 = 13.84 bbls
No water ahead, behind, CW, spacer 0 bbls
47 Single Stage Cementing
Example: Problem 1 (Continued)Lead mix water 145sx x 8.56 gal/sx = 1241.2 gal = 29.55 bbls
42 gal/bbl
Tail mix water 335sx x 4.97 ga/sx = 1664.95 gal = 39.64 bbls
42 gal/bbl
Total mix water 69.19 bbls
20% safety margin : 66.19 bbl x 20/100 = 13.84 bbls
No water ahead, behind, CW, spacer 0 bbls
Priming, washing up 20 bbls
48 Single Stage Cementing
Example: Problem 1 (Continued)Lead mix water 145sx x 8.56 gal/sx = 1241.2 gal = 29.55 bbls
42 gal/bbl
Tail mix water 335sx x 4.97 ga/sx = 1664.95 gal = 39.64 bbls
42 gal/bbl
Total mix water 69.19 bbls
20% safety margin : 66.19 bbl x 20/100 = 13.84 bbls
No water ahead, behind, CW, spacer 0 bbls
Priming, washing up 20 bbls
Total water needed 103 bbls
49 Single Stage Cementing
Additives - Step ESolid AdditivesCalculated as a % by weight of dry cement.– Except: Salt– Small amounts will not effect calculation
Liquid AdditivesCalculated as gallons of additives per sack of bulk cementSubtract total amount of liquid additives from amount of mix fluid to have real amount of mix water.
50 Single Stage Cementing
Example: Problem 1 (Continued)Lead 6% D20 BWOC (145 sks)Tail 0.2 gal/sack of D80 (335 sks)Solid Additives
145 sacks x 94 lbs/sack x 6/100 = 817.8 lbsLiquid Additives
335 sacks x 0.2 gal/sack = 67 galNote : Mix water of tail slurry will change
Mix fluid: 335sx x 4.97 gal/sk =1664.95 galMix water = Mix fluid - liquid additives
1664.95 gal - 67 gal = 38.1 bbl42 gal/bbl
51 Single Stage Cementing
DisplacementTo FLOAT COLLAR unless otherwise stated
Exceptions1. STAB-IN CEMENTING:
– Displacement to 10-15’ before stab-in shoe– Check returns - OK - pull out and circulate
2. GUIDE SHOE:– Displace to 20-30’ before shoe
NEVER OVERDISPLACE
52 Single Stage Cementing
Displacement
To FLOAT COLLAR unless otherwise statedExceptions1. STAB-IN CEMENTING:
– Displacement to 10-15’ before stab-in shoe– Check returns - OK - pull out and circulate
2. GUIDE SHOE:– Displace to 20-30’ before shoe
NEVER OVERDISPLACE
53 Single Stage Cementing
Estimated Job Time - Step GMIXING TIME
+DISPLACEMENT TIME
+10 MINUTES (DROP PLUGS ...)
= ESTIMATION OF JOB TIME
1 1/2 HOUR (SAFETY)
= MINIMUM THICKENING TIME
54 Single Stage Cementing
Estimated Job Time - Problem 1 (Continued)
Mixing time + Displacement time + Plugs mixing time:
Lead 42.8 : 4 bpm 10.5 mins 11minsTail 68.6 : 8bpm 8.5 mins 9 mins
Displacement: 4510ft x 0.0361 bbl/ft = 162.8 bbl: 12 bpm13.6 mins 14 mins
Dropping Plugs 10 minsTotal 44 mins
To allow a safe margin to do this job we expect at least 1 hr extra for the cement to be still pumpable after it is put in place.
ie, 1hrs 44 mins
55 Single Stage Cementing
Examples - Example 1Calculate : Slurry Volumes, Cement Volumes,
Mix Water, Additives, DisplacementJob Time
Well Data: 9 5/8” 53.5 lb/ft casing, shoe at 9800’,collar at 9760’, OH 12 1/4” + 25% excess,previous casing 13 3/8” 68 lb/ft at 2900’
Slurries: Lead: 5 bpm 9300’ - surface
Class “G” @ 12.8 ppg12% BWOC Bentonite0.3% BWOC D13 Tail: 3 bpm 9800’ - 9300’Class “G” Neat @ 15.8 ppg0.05% BWOC D280.5% BWOC D65
Displacement: 8 bpm
56 Single Stage Cementing
Examples - Example 1Calculate : Slurry Volumes, Cement Volumes,
Mix Water, Additives, DisplacementJob Time
Well Data: 9 5/8” 53.5 lb/ft casing, shoe at 9800’,collar at 9760’, OH 12 1/4” + 25% excess,previous casing 13 3/8” 68 lb/ft at 2900’
Sluuries: Lead: 5 bpm 9300’ - surface
Class “G” @ 12.8 ppg12% BWOC Bentonite0.3% BWOC D13 Tail: 3 bpm 9800’ - 9300’Class “G” Neat @ 15.8 ppg0.05% BWOC D280.5% BWOC D65
Displacement: 8 bpm
2
34
1
9 5/8", 53.5 lbs/ft
13 3/8" , 68 lbs/ft
2900'
12 1/4" OH
9760'
9800'
9300'
3
2
57 Single Stage Cementing
Solution - Example 1
Capacities– CAS/CAS : 0.3354 cuft/ft– CAS OH : 0.3132 cuft/ft– CAS : 0.3973 cuft/ft , 0.0708 bbl/ft
1. Volumes
58 Single Stage Cementing
Solution - Example 1Capacities– CAS/CAS : 0.3354 cuft/ft– CAS OH : 0.3132 cuft/ft– CAS : 0.3973 cuft/ft , 0.0708 bbl/ft
1. Volumes
Tail(3) 9800ft - 9300ft x 0.3132 cuft/ft = 156.cuft (4) 40ft x 0.3973 cuft/ft = 15.9 cuft
Excess 156.6 cuft x 0.25 = 39.2 cuft
Total = 211.7 cuft
Lead (1) 2900ft x 0.3354 cuft/ft = 972.7 cuft (2) 9300ft - 2900ft x 0.3132 = 2004 cuft
Excess = 2004 cuft x 0.25 = 501 cuft
Total = 3477 cuft
59 Single Stage Cementing
Solution - Example 1• Capacities
CAS/CAS :0.3354 CUFT/FTCAS OH :0.3132 CUFT/FTCAS : 0.3973 CUFT/FT, 0.0708 BBL/FT
• 1. Volumes
Tail(3) 9800ft - 9300ft x 0.3132 cuft/ft = 156.cuft (4) 40ft x 0.3973 cuft/ft = 15.9 cuft
Excess 156.6 cuft x 0.25 = 39.2 cuft
Total = 211.7 cuft
Lead (1) 2900ft x 0.3354 cuft/ft = 972.7 cuft (2) 9300ft - 2900ft x 0.3132 = 2004 cuft
Excess = 2004 cuft x 0.25 = 501 cuft
Total = 3477 cuft
• 2. Yield
Handbook 700.013 2.165 cuft/sk (lead)
700.006 1.15 cuft/sk (tail)
60 Single Stage Cementing
Solution - Example 13. CementLead : 3477 cuft = 1606 sacks
2.165 cuft/sk
Tail : 211.7 cuft = 184 sacks1.15 cuft/sk
4. Mix FluidLead : 1606sk x 12.15 gals/sk = 464.5 bbls
42 gal/bbl
Tail : 184sk x 4.97 gals/sk = 21.8 bbls42 gal/bbl
61 Single Stage Cementing
Solution - Example 1
5. AdditivesLead : D20 : 1606sk x 94lbs/sk x 0.12 = 18116 lbs
D13 : 1606sk x 94lbs/sk x 0.003 = 453 lbsTail : D28 : 184sk x 94lbs/sk x 0.0005 = 8.6 lbs
D65 : 184sk x 94lbs/sk x 0.005 = 86 lbs
62 Single Stage Cementing
Solution - Example 16. Displacement
9760ft x 0.0708 bbl/ft = 691 bbls
7. Job Thickening TimeLead 3477 cuft = 124 min
5.6146 cuft/bbl x 5 bpmTail : 211.7 cuft = 13 min
5.6146 cuft/bbl x 3 bpmDisplacement: 691 bbls = 86 min
8 bpmDrop Plugs = 10 minSafety = 60 min
298 min Minimum TT is 4 hrs 53 min
63 Single Stage Cementing
Example 2Data :Casing : 9 5/8”, 53.5 lbs/ft, 8600’
7”, 29 lbs/ft, 14300’Float collar - 14230’
Open hole : 8 1/2”Section from 10200’ - 10800’ : 9”
Cement : Lead : - Top surface @ 7 bpm- “G” at 13.5 ppg- 0.05 gals/sk D109- 0.1 gals/sk D80- 8% BWOC - D20
Tail : - 250 sacks @ 5 bpm- Class “G” @ 15.7 ppg- 30% BWOC D66- 0.1 gals/sk D81- 0.5 gals/sk D603
Calculate : Slurry Volume Cement VolumeMix water AdditivesDisplacement @ 7 bpm Job Time
64 Single Stage Cementing
Solution - Example 2
234
1
3
210200'
9" OH
4
56
7", 29 lbs/ft
9 5/8" , 53.5 lbs/ft
8600'8.5" OH
14230'
14300'
10800'
11507'
65 Single Stage Cementing
Solution - Example 2Capacities
– CAS/CAS : 0.1301 cuft/ft CAS OH : 0.1268 cuft/ft– CAS/OHX : 0.1745 cuft/ft CAS : 0.2086 cuft/ft , 0.0371 bbl/ft
1. VolumesTail : Yield is 1.475 cuft/sk
250 sacks---> 250 x 1.475 = 368.75 cuftVolume (5) + (6) = 368.75 cuft(6) = 70 x 0.2086 = 14.6 cuft(5) = 368.75 - 14.6 = 354.15 cuft
Height in annulus 354.15 cuft = 2793’0.1268 cuft/ft
14300 - 2793' = 11, 507'Lead: Surface - 11, 507'
(1) 8600 x 0.1301 = 1118.86 cuft(2) (10200 - 8600) x 0.1268 = 202.88 cuft(3) (10800 - 10200) x 0.1745 = 104.70 cuft(4) (11507 - 10800) x 0.1268 = 89.64 cuft
Total Lead = 1516.1 cu ft
66 Single Stage Cementing
Solution - Example 22. Cement sacks
Lead : Handbook : 13.5 ppgClass"G"8% D20Yield = 1.825 cuft/Sk
1516.1 cuft = 830.7 = 831 sacks1.825 cuft/sack
Tail : 250 sacks
3. Mix fluidLead : 831sk x 9.76 gal/sk = 193.1 bbls
42 gal/bblTail : 250 sks x 6.15 gals/sk = 36.6 bbls
42 gal/bbl
67 Single Stage Cementing
Solution - Example 24. Additives
Lead: D20 : 831 sks x 94 x 0.08 = 6249 lbsD109 : 831 sks x 0.05 gals/sk = 41.5 galsD80 : 831 sks x 0.1 gals/sk = 83.1 galsTotal fluid = 124.6 gals
Tail:D66 : 250 sks x 94 x 0.3 = 7050 lbsD81 : 250 sks x 0.1 gals/sk = 25 galsD603 : 250 sks x 0.5 gals/sk = 125 galsTotal fluid = 150 gals
5. Mix waterLead: 193.bbls - 124.6gal = 190.1 bbls
42gal/bblTail: 36.6bbls - 150gal = 33.0 bbls
42gal/bbl
68 Single Stage Cementing
Solution - Example 26. Displacement
– 14230ft' x 0.0371 bbl/ft = 527.9 bbl
7. Job Thickening Time
Lead : 270 bbls : 7 bpm = 38.5 min
Tail : 65.7 bbls : 5 bpm = 13.1 min
Plugs : = 10 min
Displacement 527.9 bbls : 7 bpm = 75 min
Safety Margin : = 60 min
Min TT is 3 hrs 16 min
69 Single Stage Cementing
Job Pressures
2
34
1
9 5/8", 53.5 lbs/ft
13 3/8" , 68 lbs/ft
2900'
12 1/4" OH
9760'
9800'
9300'
3
2
Example No 1
Tail Slurry at 15.8 ppg
– Top of Tail at 9300 Ft
– Lead slurry at 12.8 ppg to surface
Displace with 11.5 ppg Mud
Find differential pressure at end of Job
70 Single Stage Cementing
Hydrostatic Pressure Calcs
Tubing HydrostaticMud Hydrostatic
– Pmud = 11.5 x 9760 x 0.052– Pmud = 5836 psi
Annular HydrostaticTail Slurry Hydrostatic
– PTail = 15.8 x(9760 - 9300)x 0.052– PTail = 378 psi
Lead Slurry Hydrostatic– PLead= 12.8 x 9300 x 0.052– PLead = 6190 psi
Differential pressure– PDiff= Annular Hyd. - Tubing Hyd.
= (6190 +378) - 5836– PDiff = 732 psi = Surface pump
pressure
2
34
1
9 5/8", 53.5 lbs/ft
13 3/8" , 68 lbs/ft
2900'
12 1/4" OH
9760'
9800'
9300'
3
2
71 Single Stage Cementing
Long String Cement Calcs
2
34
1
9 5/8", 40 lbs/ft
13 3/8" , 77 lbs/ft
3150'
12 1/4" OH
9900'
9980'
9480'
3
2
Mud @ 11.3 ppg
Chemical wash @ 8.4 ppg
Lead Slurry @ 12.8 ppg
Tail Slurry @ 15.8 ppg
2100’
Primary Cement Job– 9 5/8” Csg , 40 lbs/ft– Shoe @ 9980’ - Collar @ 9900’– Tail slurry @ 15.8 ppg to 9480’– Lead slurry @ 12.8 ppg to 2100’– 50 Bbls Chemical Wash ahead.
Previous Casing– 13 3/8“ Csg ,77 lbs/ft– Shoe @ 3150’
12 1/4” OH - Assume 10% Excess.– Find Lead, Tail and Displacement
Volumes required.– Calculate Differential pressure at
the end of the job (ignore friction).
72 Single Stage Cementing
Long String Cement Calcs - Solution
2
34
1
9 5/8", 40 lbs/ft
13 3/8" , 77 lbs/ft
3150'
12 1/4" OH
9900'
9980'
9480'
3
2
Mud @ 11.3 ppg
Chemical wash @ 8.4 ppg
Lead Slurry @ 12.8 ppg
Tail Slurry @ 15.8 ppg
2100’
Capacities– Csg/OH Ann = 0.0558 bbls/ft– Csg/Csg Ann = 0.0564 bbls/ft– 9 5/8” Csg cap (40 #/ft) = 0.0758 bbls/ft
Tail volume = Vol of Shoe track+ Vol outside csg (with XS)
= 0.0758 x (9980 - 9900)+ 0.0558 x (9980 - 9480) x 1.10
= 6.06 + 30.69 = 36.75 = 37 Bbls= 206.3 cuft
Lead volume = Vol in Csg/OH Ann (with XS)+ Vol in Csg/Csg Ann
= 0.0558 x (9480 - 3150) x 1.10+ 0.0564 x (3150 - 2100)
= 388.53 + 59.22 = 447.75= 448 Bbls= 2514.04 cuft
73 Single Stage Cementing
Long String Cement Calcs - Solution
2
34
1
9 5/8", 40 lbs/ft
13 3/8" , 77 lbs/ft
3150'
12 1/4" OH
9900'
9980'
9480'
3
2
Mud @ 11.3 ppg
Chemical wash @ 8.4 ppg
Lead Slurry @ 12.8 ppg
Tail Slurry @ 15.8 ppg
2100’
Capacities– Csg/OH Ann = 0.0558 bbls/ft– Csg/Csg Ann = 0.0564 bbls/ft– 9 5/8” Csg cap (40 #/ft) = 0.0758
bbls/ftDisplacement volume = Csg Vol to
float collar
= 0.0758 x 9900= 750 Bbls
Differential pressure at end of Job := Hydrostatic of Lead and tail cement columns + Hydrostatic of wash + Hydrostatic of remaining mud in annulus LESS Hydrostatic of displacing fluid + Hydrostatic of Tail cement in shoe joint
74 Single Stage Cementing
Long String Cement Calcs - Solution
2
34
1
9 5/8", 40 lbs/ft
13 3/8" , 77 lbs/ft
3150'
12 1/4" OH
9900'
9980'
9480'
3
2
Mud @ 11.3 ppg
Chemical wash @ 8.4 ppg
Lead Slurry @ 12.8 ppg
Tail Slurry @ 15.8 ppg
2100’
Capacities– Csg/OH Ann = 0.0558 bbls/ft– Csg/Csg Ann = 0.0564 bbls/ft– 9 5/8” Csg cap (40 #/ft) = 0.0758
bbls/ftHeight of Chemical wash in Csg/Csg
Ann= 50 / 0.0564= 886 ft
Height of Tail = 9980 - 9480 = 500 ftHeight of Lead = 9480 - 2100 = 7380 ftHeight of Chem Wash = 886 ft
Remainder is Mud behind casing= 9900 - (420 + 7380 + 886)= 1214 ft
75 Single Stage Cementing
Long String Cement Calcs - Solution
2
34
1
9 5/8", 40 lbs/ft
13 3/8" , 77 lbs/ft
3150'
12 1/4" OH
9900'
9980'
9480'
3
2
Mud @ 11.3 ppg
Chemical wash @ 8.4 ppg
Lead Slurry @ 12.8 ppg
Tail Slurry @ 15.8 ppg
2100’
Annulus hydrostatic is total of Cement slurries + Chem Wash + Mud := 15.8 x 500 x 0.052 ( =Tail slurry)+ 12.8 x 7380 x 0.052 ( = Lead slurry)+ 8.4 x 886 x 0.052 (= Chem Wash)+ 11.3 x 1214 x 0.052 ( Mud in Ann)
= 410 + 4912 + 387 + 713= 6423 psi
Hydrostatic inside casing := 11.3 x 9900 x 0.052 (=Mud, disp.)+ 15.8 x 80 x 0.052 (=Tail slurry)= 5817 + 65.7 = 5883 psiDifferential pressure at float collar :
= psi outside csg - psi inside csg= 6423 - 5883= 540 psi