oilwell cementing calculation
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Single Stage Calculations
2 Single Stage Cementing
1. Casing in casing
Open Hole
PreviousCasing
Collar
Shoe3
1
Volumes to be Calculated : Step A
3 Single Stage Cementing
Volumes to be Calculated : Step A
1. Casing in casing
2. Casing in open hole
Open Hole
PreviousCasing
Collar
Shoe
2
3
1
4 Single Stage Cementing
Volumes to be Calculated : Step A
1. Casing in casing
2. Casing in open hole
3. Inside casing (between collar and shoe)
Open Hole
PreviousCasing
Collar
Shoe
2
3
1
3
5 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.
6 Single Stage Cementing
Problem 1
Casing : 7” - 32 LB/Ft
Shoe : 4600’
Collar : 4510’
Previous casing : 9 5/8 - 47 LB/Ft
Shoe : 2670’
Open hole : 8.5”
Top of cement : 1000’
Calculate Total Amount of Slurry Required in CuFt
7 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
8 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
9 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
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
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
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
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
12 Single Stage Cementing
Excess
Excess in only calculated on AnnularVolume in THE OPEN HOLE
OnlyHere
13 Single Stage Cementing
Example: Problem 1
OH 50% Excess
OH volume (2) of the previous problem:244.7 cuft
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
14 Single Stage Cementing
Slurry Yield - Step B
The volume of slurry produced when one sack of cement ismixed with water is called
YIELD
15 Single Stage Cementing
Slurry Yield - Step BThe volume of slurry produced when one sack of cement is
mixed with water is called YIELD
+CEMENTCEMENT
16 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 called YIELDYIELD
WATER =+CEMENTCEMENT
17 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 called YIELDYIELD
WATER =
The unit of slurry yield is cuft/sackThe unit of slurry yield is cuft/sack
+ SLURRYSLURRYCEMENTCEMENT
18 Single Stage Cementing
Note:
1 sack of cement of 94 lbs
4.97 gals of water
= 1 cuft= 1 cuft
= 0.66 cuft= 0.66 cuft
19 Single Stage Cementing
Note:
1 sack of cement1 sack of cement of 94 lbsof 94 lbs
4.97 gals of water4.97 gals of water
1 cuft + 0.66 cuft1 cuft + 0.66 cuft
= 1 cuft= 1 cuft
= 0.66 cuft= 0.66 cuft
= 1.66 cuft= 1.66 cuft
20 Single Stage Cementing
Note:
1 sack of cement1 sack of cement of 94 lbsof 94 lbs
4.97 gals of water4.97 gals of water
1 cuft + 0.66 cuft1 cuft + 0.66 cuft
= 1 cuft= 1 cuft
= 0.66 cuft= 0.66 cuft
= 1.66 cuft= 1.66 cuft
1.15 cuft/sack1.15 cuft/sack
But the But the Handbook states:Handbook states:
WHY ?WHY ?
21 Single Stage Cementing
Bulk vs Absolute
One drum full One drum full of dry cementof dry cement(1 drum = 1 cuft)(1 drum = 1 cuft)
Same size drumSame size drum0.66 of water0.66 of water
22 Single Stage Cementing
Bulk vs Absolute
One drum full One drum full of dry cementof dry cement(1 drum = 1 cuft)(1 drum = 1 cuft)
Same size drumSame size drum0.66 of water0.66 of water
Air in pore spaces willbe displaced by water
Pour waterPour waterinto cementinto cement
23 Single Stage Cementing
Note
Yield varies with density
Basically, 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
24 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.
25 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
26 Single Stage Cementing
Example: Problem 1 (Continued)
Previous Problem:Lead volume [1] : 240.2 cuft Tail volume [2 + 3] : 367.05 cuft + 18.2 cuft 385.35 cuft
27 Single Stage Cementing
Example: Problem 1 (Continued)Previous Problem:
Lead volume [1] : 240.2 cuft Tail volume [2 + 3] : 367.05 cuft
+ 18.2 cuft 385.35 cuft
Use:Lead Slurry : Class G + 6% D20 at 13.9 ppgTail Slurry Neat : Class G at 15.8 ppg
Cement volume Lead:
28 Single Stage Cementing
Example: Problem 1 (Continued)Previous Problem:
Lead volume [1] : 240.2 cuft Tail volume [2 + 3] : 367.05 cuft
+ 18.2 cuft 385.35 cuftUse: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:
29 Single Stage Cementing
Example: Problem 1 (Continued)Previous Problem:
Lead volume [1] : 240.2 cuft Tail volume [2 + 3] : 367.05 cuft
+ 18.2 cuft 385.35 cuftUse: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
385.25 cuft = 335.0 sacks 1.15 cuft/sack
Cement volume Tail:
30 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 multiply
Mix Fluid = gal/sack x number of sacks
CONVERT TO BBLS
(Your displacement tanks are in bbls)
31 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
32 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
33 Single Stage Cementing
Example: Problem 1 (Continued)
Lead mix water 145sx x 8.56 gal/sx
34 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
35 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
36 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
37 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
38 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
39 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
40 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
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
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
42 Single Stage Cementing
Additives - Step E
Solid Additives Calculated as a % by weight of dry cement.
– Except: Salt– Small amounts will not effect calculation
Liquid Additives Calculated as gallons of additives per sack of bulk
cement Subtract total amount of liquid additives from
amount of mix fluid to have real amount of mix water.
43 Single Stage Cementing
Example: Problem 1 (Continued)Lead 6% Bentonite BWOC (145 sks)
Tail 0.2 gal/sack of Dispersant (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 bbl 42 gal/bbl
44 Single Stage Cementing
Displacement
To FLOAT COLLAR unless otherwise stated
Exceptions
1. 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
45 Single Stage Cementing
Displacement
To FLOAT COLLAR unless otherwise stated
Exceptions
1. 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
46 Single Stage Cementing
Estimated Job Time - Step G MIXING TIME + DISPLACEMENT TIME + 10 MINUTES (DROP PLUGS ...) = ESTIMATION OF JOB TIME 1 HOUR (SAFETY)
= MINIMUM THICKENING TIME
47 Single Stage Cementing
Estimated Job Time - Problem 1 (Continued)
Mixing time + Displacement time + Plugs mixing time:
Lead 42.8 : 4 bpm 10.5 mins 11mins Tail 68.6 : 8bpm 8.5 mins 9 mins
Displacement: 4510ft x 0.0361 bbl/ft = 162.8 bbl : 12 bpm 13.6 mins 14 mins Dropping Plugs 10 mins Total 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
48 Single Stage Cementing
Examples - Example 1Calculate : Slurry Volumes, Cement Volumes,
Mix Water, Additives, Displacement
Job 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 ppg
12% BWOC Bentonite
0.3% BWOC D13
Tail: 3 bpm 9800’ - 9300’
Class “G” Neat @ 15.8 ppg
0.05% BWOC D28
0.5% BWOC D65
Displacement: 8 bpm
49 Single Stage Cementing
Examples - Example 1Calculate : Slurry Volumes, Cement Volumes,
Mix Water, Additives, Displacement
Job 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 ppg
12% BWOC Bentonite
0.3% BWOC D13
Tail: 3 bpm 9800’ - 9300’
Class “G” Neat @ 15.8 ppg
0.05% BWOC D28
0.5% 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
50 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
51 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
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
52 Single Stage Cementing
Solution - Example 1
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
• CapacitiesCAS/CAS :0.3354 CUFT/FTCAS OH :0.3132 CUFT/FTCAS : 0.3973 CUFT/FT, 0.0708 BBL/FT
• 1. Volumes
• 2. Yield
Handbook 700.013 2.165 cuft/sk (lead)
700.006 1.15 cuft/sk (tail)
53 Single Stage Cementing
Solution - Example 1 3. Cement
Lead : 3477 cuft = 1606 sacks 2.165 cuft/sk
Tail : 211.7 cuft = 184 sacks 1.15 cuft/sk
4. Mix Fluid
Lead : 1606sk x 12.15 gals/sk = 464.5 bbls 42 gal/bbl
Tail : 184sk x 4.97 gals/sk = 21.8 bbls 42 gal/bbl
54 Single Stage Cementing
Solution - Example 1
5. Additives
Lead : D20 : 1606sk x 94lbs/sk x 0.12 = 18116 lbs
D13 : 1606sk x 94lbs/sk x 0.003 = 453 lbs
Tail : D28 : 184sk x 94lbs/sk x 0.0005 = 8.6 lbs
D65 : 184sk x 94lbs/sk x 0.005 = 86 lbs
55 Single Stage Cementing
Solution - Example 1 6. Displacement
9760ft x 0.0708 bbl/ft = 691 bbls
7. Job Thickening Time
Lead 3477 cuft = 124 min
5.6146 cuft/bbl x 5 bpm
Tail : 211.7 cuft = 13 min
5.6146 cuft/bbl x 3 bpm
Displacement: 691 bbls = 86 min
8 bpm
Drop Plugs = 10 min
Safety = 60 min
298 min
Minimum TT is 4 hrs 53 min
56 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 Volume Mix water Additives Displacement @ 7 bpm Job Time
57 Single Stage Cementing
Solution - Example 2
23
4
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'
58 Single Stage Cementing
Solution - Example 2 Capacities– 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. Volumes
Tail : 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
59 Single Stage Cementing
Solution - Example 2 2. Cement sacks
Lead : Handbook : 13.5 ppg Class"G" 8% D20 Yield = 1.825 cuft/Sk 1516.1 cuft = 830.7 = 831 sacks
1.825 cuft/sackTail : 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
60 Single Stage Cementing
Solution - Example 2 4. Additives
Lead: D20 : 831 sks x 94 x 0.08 = 6249 lbs D109 : 831 sks x 0.05 gals/sk =
41.5 gals D80 : 831 sks x 0.1 gals/sk =
83.1 gals Total fluid = 124.6 galsTail: D66 : 250 sks x 94 x 0.3 = 7050 lbs D81 : 250 sks x 0.1 gals/sk = 25 gals D603 : 250 sks x 0.5 gals/sk = 125
gals Total fluid = 150 gals
5. Mix waterLead: 193.bbls - 124.6gal = 190.1 bbls 42gal/bblTail: 36.6bbls - 150gal = 33.0 bbls 42gal/bbl
61 Single Stage Cementing
Solution - Example 2 6. 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
62 Single Stage Cementing
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
Job Pressures
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
63 Single Stage Cementing
Hydrostatic Pressure Calcs
Tubing Hydrostatic Mud Hydrostatic
– Pmud = 11.5 x 9760 x 0.052– Pmud = 5836 psi
Annular Hydrostatic Tail 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
64 Single Stage Cementing
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’
Long String Cement Calcs
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).
65 Single Stage Cementing
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’
Long String Cement Calcs - Solution
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
66 Single Stage Cementing
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’
Long String Cement Calcs - Solution
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 Displacement 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
67 Single Stage Cementing
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’
Long String Cement Calcs - Solution
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 Height of Chemical wash in
Csg/Csg Ann= 50 / 0.0564= 886 ft
Height of Tail = 9980 - 9480 = 500 ft
Height of Lead = 9480 - 2100 = 7380 ft
Height of Chem Wash = 886 ft Remainder is Mud behind casing
= 9900 - (420 + 7380 + 886) = 1214 ft
68 Single Stage Cementing
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’
Long String Cement Calcs - Solution
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 psi
Differential pressure at float collar := psi outside csg - psi inside csg= 6423 - 5883= 540 psi
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