well casing string

1. LECTURE 2:
CASING DESIGN PRATICES
BY
DR. A.K.PATHAK
DEPARTMENT OF PETROLEUM ENGINEERING
INDIAN SCHOOL OF MINES
DHANBAD - 826004
E-mail: akhilendra_pathak@yahoo.co.i

2. CASING CONFIGURATIONS
2

3. Types of Casing String
Conductor Casing
- Surface Casing
 - Intermediate Casing
 - Production Casing
 - Liners
3

4. FUNCTIONS OF CASING
 To prevent caving of the hole
 To prevent contamination of fresh water in the
upper sands
 To exclude water from the producing formation
 To confine production to the well bore
 To provide a means for controlling pressure and
 To facilitate installation of the subsurface
equipment required in case of artificial lift
method applications.
4

5. CASING PIPE
A CASING PIPE IS
REFERRED TO A PLAIN
PIPE WHOSE BOTH ENDS
ARE THREADED AND A
COUPLING IS ATTAHED
AT ONE END
5

6. Casing Pipe
6

7. SPECIFICATIONS OF CASING
PIPES
7

8. SPECIFICATIONS OF
CASING PIPES
 Size
 Nominal weight, governed by wall thickness.
 Grade of steel
 Threads & Coupling type.
8

9. GRADES & SPECIFICATION OF
CASING PIPES
---------------------------------------------------------------------------------------.
Casing Ym Ya C
Grade psi psi
----------------------------------------------------------------------------------------.
F-25 25,000 35,000 134
H-40 40,000 50,000 182
J-55,K-55 55,000 65,000 242.5
N-80,L-80 80,000 85,000 282
P-110 110,000 122,500 369
----------------------------------------------------------------------------------------.
9

10. Length ranges
 Range 1: 16-25 ft. average 22 ft
 Range 2: 25-34 ft. average 29 ft.
 Range 3: above 34 ft. average 38 ft.
 Range 0: 20 ft standard
10

11. Threads & Couplings
 Short threads and Couplings
 Long Threads & Coupling
 Buttress Threads & Couplings
 API Extreme Line Threads & Couplings
 Round Threads & Couplings
11

12. MAKE UP LOSS PER JOINT
12

13. MAKE UP LOSS
13

14. Make up loss
 It is defined as length lost during making
up the string by connecting two casing
pipes.
 L2 = 2L – LJ (1)
 Lj = 0.5 Lc - J (2)

 LT = [(1000 L) / {L – (LJ / 12)}] (3)
14

15. Make up loss
 LT = [1000 + {(LT / L) (0.5 Lc - J) / 12}]
 Lj = 0.5 Lc - J
 LT = [(1000 L) / {L – (LJ / 12)}]
15

16. Exercise
 Calculation of make up loss per joint.
 Calculation of required length of casing for
a given depth.
16

17. Linear weight of Casing pipe
17

18. Weight of Casing
wtc = (Lp . wp – 2Wt + Wc) / L (4)
Components
Lp , wp , Wt , Wc
18

19. Length and Weight of Plain Pipe
Lp = L – (0.5 Lc + J)/12 (5)
Wp = 10.68 t ( de – t) (6)
19

20. Weight of Couplings: Wc
20

21. Weight of Couplings: Wc
 WC = 0.2833 VC
 VC = 2 ( Va – Vb – Vd)
 Va = Volume of a cylinder of 0.5 LC length and diameter de
 Vb = Volume of a cylinder of M length and diameter dr
 Vd = Volume of frustum of a cone of [0.5 LC – M] length and
diameters d2 and d3
21

22. Weight of Couplings: Wc
 WC = 0.2833 VC
 VC = 2 ( Va – Vb – Vd)
 Va = 0.5 LC . ( / 4) . de
2
 Vb = M . ( / 4) . dr
2
 Vd = ( / 12) . [0.5 LC – M] . [d2
2 + d3
2 + d2 . d3]
22

23. Weight of Couplings: Wc
 VC = ( / 12) . [ 3 LC . d c
2 - 6 M dr
2 -
( LC – 2 M) . (d2
2 + d2.d3 + d3
2) ]
 Wc = 0.222 Lcdc
2 – 0.445 M.dr
2 – 0.074
( Lc – 2 M) (d2
2 + d2.d3 + d3
2) (7)
 d3 = d2 – 0.0625 ( 0.5 Lc – M) (8)

23

24. Weight of Metal Removed during
Threading: Wt
24

25. Weight of Metal Removed
during Threading: Wt
 Wt = 0.2833 Vt
 Vt = Ve – Vf – Vg
 Ve = Volume of a cylinder of Lt length and diameter de
 Vf = Volume of frustum of a cone of L1 length and diameters de and d1
 Vg = Volume of frustum of a cone of [Lt –L1 ] length and diameters d1
and d4
25

26. Weight of Metal Removed
during Threading: Wt
 Wt = 0.2833 Vt
 Vt = Ve – Vf – Vg
 Ve = Lt . ( / 4) . de
2
 Vf = ( / 12) . L1 . [de
2 + d1
2 + de . d1]
 Vg = ( / 12) . ( Lt - L1 ) . [d1
2 + d4
2 + d1 . d4]
26

27. Weight of Metal Removed
during Threading: Wt
 Vt = ( / 12) . [ 3 Lt . de
2 - L1 . (de
2 + d1
2 + d2 .
d1 ) – ( Lt - L1 ) . (d1
2 + d4
2 + d1 . d4)]
 Wt = 0.222 Ltde
2 – 0.074 ( Lt – L1) (d1
2 + d1.d4
+ d4
2) – 0.074 L1 (de
2 + d1.de + d1
2)
(9)
 d4 = d1 – 0.0625 (Lt – L1) (10)
27

28. Linear Weight of Threaded and
Coupled Casing Pipe
 wtc = (Lp . wp – 2Wt + Wc) / L
 Lp = L – (0.5 Lc + J)/12
 Wp = 10.68 t ( de – t)
 d3 = d2 – 0.0625 ( 0.5 Lc – M)
 Wc = 0.222 Lcdc
2 – 0.445 M.dr
2 – 0.074 (
Lc – 2 M) (d2
2 + d2.d3 + d3
2)
 d4 = d1 – 0.0625 (Lt – L1)
 Wt = 0.222 Ltde
2 – 0.074 ( Lt – L1) (d1
2 +
d1.d4 + d4
2) – 0.074 L1 (de
2 + d1.de + d1
2)28

29. Exercise
 Calculate Weight of Coupling.
 Calculate Weight of metal removed during
threading the pipe end.
 Calculate Linear weight of threaded and
coupled casing pipe.
29

30. Linear Weight of Threaded and
Coupled Casing Pipe
 wtc = (Lp . wp – 2Wt + Wc) / L
 Lp = {L – (0.5 Lc + J)/12}
 wtc = [{L – (0.5 Lc + J)/12}. wp – 2Wt + Wc] / L
 wtc = (1/L) [ L wp – {(Lc.wp)/24} –
{(J .wp)/12} – 2 Wt + Wc)]
30

31. Linear Weight of Threaded and
Coupled Ideal Pipe (20 ft.)
 wtc = (1/L) [ L wp – {(Lc.wp)/24} –
{(J .wp)/12} – 2 Wt + Wc)]
 wtc
’ = (1/20) [ 20 wp – {(Lc.wp)/24} – {(J
.wp)/12} – 2 Wt + Wc)] (11)
 wtc = [(20 / L) (wtc
’ – wp) + wp] (12)
31

32. Average Linear weight of casing
string
 wtc = [(20 / L) (wtc
’ – wp) + wp]
 w = LT . wtc / 1000
 LT = [(1000 L) / {L – (LJ / 12)}]
 w = [20 (wtc
’ – wp) + L.wp] / [L – (0.5 Lc -
J)/12] (13)
32

33. Exercise
 Calculate Average weight of a casing
string
33

34. Table 3: API SPECIFICATION OF CASING THREADS & COUPLINGS
SHORT THREADS & COUPLINGS
34
de t d1 d2 J Lc Lt L1 M dr dc
4½ All
4.43175 4.40337 0.5 5 2
0.625
0.704 4 19/32 5
5 All
4.93175 4.90337 0.5 61/2 2.75
0.625 0.704
5 3/32 5.563
5½ All
5.43175 5.40337 0.5 63/4 2.875
0.625 0.704
5 19/32 6.05
6
All
5.93175 5.90337 0.5 7 3
0.625 0.704
6 3/32 6.625
6⅝
All
6.55675 6.52837 0.5 71/4 3.125
0.625 0.704
6 23/32 7.39
7
All
6.93175 6.90337 0.5 71/4 3.125
0.625 0.704
7 3/32 7.656
7⅝
All
7.55675 7.52418 0.5 71/2 3.25
0.625 0.709
7 23/32 8.5
8⅝
All
8.55675 8.52418 0.5 73/4 3.375
0.625 0.709
8 23/32 9.625
9⅝
All
9.55675 9.52418 0.5 73/4 3.375
0.625 0.709
7 23/32 10.625
10¾
All
10.68175 10.64918 0.5 8 3.5
0.625 0.709
10 27/32 11.75
11¾
All
11.68175 11.64918 0.5 8 3.5
0.625 0.709
11 27/32 12.75
13⅜
All
13.30675 13.27418 0.5 8 3.5
0.625 0.709
13 15/32 14.375
16
All
15.93175 15.89918 0.5 9 4
0.625 0.709
16 3/32 17
20 All 19.93175 19.89918 0.5 9 4
0.625 0.709
20 3/32 21

35. Table 4: API SPECIFICATION OF CASING THREADS & COUPLINGS
LONG THREADS & COUPLINGS
de t d1 d2 J Lc Lt L1 M dr dc
4½ All 4.43175
4.40337 0.5
7 3.000 0.625 0.704 4 19/32 5
5 All
4.93175 4.90337 0.5
73/4 3.395 0.625 0.704
5 3/32 5.563
5½ All
5.43175 5.40337 0.5
8 3.500 0.625 0.704
5 19/32 6.05
6
All
5.93175 5.90337 0.5
81/2 3.750 0.625 0.704
6 3/32 6.625
6⅝
All
6.55675 6.52837 0.5
83/4 3.875 0.625 0.704
6 23/32 7.39
7
All
6.93175 6.90337 0.5
9 4.000 0.625 0.704
7 3/32 7.656
7⅝
All
7.55675 7.52418 0.5
91/4 4.125 0.625 0.704
7 23/32 8.5
8⅝
All
8.55675 8.52418 0.5
10 4.500 0.625 0.704
8 23/32 9.625
9⅝
All
9.55675 9.52418 0.5
101/2 4.750 0.625 0.704
9 23/32 10.625
35

36. PROPERTIES OF
CASING PIPES
36

37. Joint Strength
It is the maximum axial load under the perfect
thread of joint of a particular grade casing for
which the casing can withstand without any joint
failure. Unit in Lbs.
FJS = C [33.71 – de] [24.45 t – 0.742] [ de – t – 0.07125] (14)
FJl = 1.647 C [25.58 – de] [24.45 t – 0.742] [ de – t – 0.07125] (15)
37

38. Burst Pressure
 It is defined as the limit of internal fluid
pressure of a casing pipe against which
the pipe can withstand without any burst
failure.
 Pb = 1.75 Ym . t / de (16)
38

39. Collapse Pressure
It is defines as the limit of
external fluid pressure
exerting on a pipe against
which the pipe can
withstand without any
collapse failure.
39

40. Collapse Pressure
 For Elastic Failure:

 46.95 X 106
 PC = ---------------------------------
(de/t)[(de/t) – 1]2
40

41. Collapse Pressure
 For plastic failure with de/t less than 14

 [(de/t) – 1]
 PC = 1.50 Ym [--------------------------]
 (de/t)2
 For plastic failure with de/t greater than 14

 1.877
 PC = Ya [------------- - 0.0345]
 (de/t)
41

42. Collapse Pressure
 Stewart Equation for de/t less than 43.5 only for F-25 casing

 65,000
 PC = [---------------- - 1040]
 (de/t)

 Stewart Equation for de/t greater than 43.5 only for F-25 casing

 37.66 X 106
 PC = [----------------------]
 (de/t)3
42

43. CALCULATION OF COLLAPSE PRESSURE
43
GRADE D/t Ratio
H40 16.44 and less
J55, K55 and E 14.80 and less
C75 and E 13.67 and less
N80 13.38 and less
C95 12.83 and less
P105 12.56 and less
P110 12.42 and less
135 11.90 and less
140 11.95 and less
For minimum collapse failure in the plastic range with minimum
yield stress limitations :
Pc = 2 Ym[(D/t-1)/(D/t)2 ……(I)
Applicable D/t ratios for application of formula (1) are as follows :

44. CALCULATION OF COLLAPSE PRESSURE
44
GRADE FORMULA FACTOR D/t Ratio
A’ B’ C
H40 2.950 .0463 755 16.44 to 26.62
J55, K55 and E 2.990 .0541 1205 14.80 to 24.99
C75 and E 3.060 .0642 1805 13.67 to 23.09
N80 3.070 .0667 1955 13.38 to 22.46
C95 3.125 .0745 2405 12.83 to 21.21
P105 3.162 .0795 2700 12.56 to 20.66
P110 3.180 .0820 2855 12.42 to 20.29
135 3.280 .0945 3600 11.90 to 19.14
140 3.295 .0970 3750 11.95 to 18.95
For minimum collapse failure in plastic range :-
Pc = Ym [ (A’t / D) – B’] – C (II)
Factors and applicable D/t ratios for application of
formula 2 and as follows :

45. CALCULATION OF COLLAPSE PRESSURE
45
GRADE FORMULA FACTOR D/t Ratio
A’ B’
H40 2.047 .03125 26.62 to 42.70
J55, K55 and E 1.990 .0360 24.99 to 37.20
C75 and E 1.985 .0417 23.09 to 32.04
N80 1.998 .0424 22.46 to 31.05
C95 2.047 .0490 21.21 to 28.25
P105 2.052 .0515 20.66 to 26.88
P110 2.075 .0535 20.29 to 26.20
135 2.129 .0613 19.14 to 23.42
140 2.142 .0630 18.95 to 23.00
Pc = Ym [ (At / D) – B’] ………………………… (III)

46. CALCULATION OF COLLAPSE PRESSURE
46
GRADE D/t Ratio
H40 42.70 and greater
J55, K55 and E 37.20 and greater
C75 and E 32.05 and greater
N80 31.05 and greater
C95 28.25 and greater
P105 26.88 and greater
P110 26.20 and greater
135 23.42 and greater
140 23.00 and greater
For minimum collapse failure in elastic range :-
Pc = 46.95 x 106 / ( D/t) [ (D/t)-1]2 ---(IV)
Applicable D/t ratios for application of formula 4
and as follows :-

47. Exercise
 Tabulate the properties of casing pipes
 Joint Strength
 Collapse Pressure
 Burst Pressure
 Casing Yield loading constant
47

48. Effect of Axial Load on Collapse
Pressure of a Casing Pipe
48
(PCC / PC) = (yt / ya)
Yz
2 = - (W/A)
According to Helmquist & Nadai equation
Ya
2 = Yt
2 – Yt . Yz + Yz
2 K = 2 Ya . A
Devide the equation by Ya
2
(Yt
2 – Yt . Yz + Yz
2 ) / Ya
2 = 1
(PCC / PC)2 + {2 . W . PCC / K . Pc } + {(4 W2 / K2) – 1} = 0
solving for PCC
Pcc = (Pc / K) [{  (K2 – 3W2)} – W] (17)

49. Exercise
 Effect of Axial Load on Collapse Pressure
 Tabulate the Corrected Collapse
Resistance Pressure (PCC) versus load
data of 9 5/8 inch 40 lbs LT&C casing
pipe and draw the collapse resistance
curve
49

50. 50

51. 51

52. 52

53. 53
OD inch Wall thick. Inch Nominal Weight ppf Grades Threads & Coupling OD inch Wall thick. Inch Nominal Weight ppf Grade Threads & Coupling
4 ½ 0.205 9.50 F,H,J S 8 5/8 0.264 24.00 F,J S
0.250 11.60 J S,L 0.304 28.00 H S
0.250 11.60 N,P L 0.352 32.00 H S
0.290 13.50 N,P L 0.352 32.00 J S,L
0.337 15.10 P L 0.400 36.00 J S,L
5 0.220 11.50 F,J S 0.400 36.00 N L
0.253 13.00 J S,L 0.450 40.00 N,P L
0.296 15.00 J S,L 0.500 44.00 N,P L
0.296 15.00 N,P L 0.557 49.00 N,P L
0.362 18.00 N,P L
5 ½ 0.228 13.00 F S 9 5/8 0.281 29.30 F S
0.244 14.00 H,J S 0.312 32.30 H S
0.275 15.50 J S,L 0.352 36.00 H S
0.304 17.00 J S,L 0.352 36.00 J S,L
0.304 17.00 N,P L 0.395 40.00 J S,L
0.361 20.00 N,P L 0.395 40.00 N L
0.451 23.00 N,P L 0.435 43.5 N,P L
6 0.238 15.00 F S 0.472 47.00 N,P L
0.288 18.00 H S 0.545 53.50 N,P L
0.288 18.00 J S,L 10 ¾ 0.279 32.75 F,H S
0.288 18.00 N L 0.350 40.50 H,J S
0.324 20.00 N L 0.400 45.50 J S
0.380 23.00 N,P L 0.450 51.00 J,N,P S
0.434 26.00 P L 0.495 55.50 N,P S
6 5/8 0.245 17.00 F S 0.545 60.70 P S
0.288 20.00 H S 0.595 65.70 P S
0.288 20.00 J S,L 11 ¾ 0.300 38.00 F S
0.352 24.00 J S,L 0.333 42.00 H S
0.352 24.00 N,P L 0.375 47.00 J S
0.475 32.00 N,P L 0.435 54.00 J S
0.489 60.00 J,N S
7 0.231 17.00 F,H S 13 3/8 0.330 48.00 F,H S
0.272 20.00 H,J S 0.380 54.50 J S
0.317 23.00 J S,L 0.430 61.00 J S
0.317 23.00 N L 0.480 68.00 J S
0.362 26.00 J S,L 0.514 72.00 N S
0.362 26.00 N,P L 16 0.312 55.00 F S
0.408 29.00 N,P L 0.375 65.00 H S
0.453 32.00 N,P L 0.438 75.00 J S
0.498 35.00 N,P L 0.495 84.00 J S
0.540 38.00 N,P L 20 0.438 94.00 F,H S
7 5/8 0.250 20.00 F S
0.300 24.00 H S
0.328 26.40 J S,L
0.328 26.40 N L
0.375 29.70 N,P L
0.430 33.70 N,P L
0.500 39.00 N,P L
Table 2: API CASING FAMILY

54. Area under the
last perfect threads
54

55. Area under the
last perfect threads
 Aj =  t ( de – t) -  h ( de – h)
 Aj =  [ t (de – t) – h (de – h)]
 Aj =  [t. de – t2 – h . de + h2]
 Aj =  [t . de – h . de + (h2 – t2 ) ]
 Aj =  [t . de – h . de - (t2 – h2) ]
 Aj =  [de (t – h) - {(t + h) (t – h)}]
 Aj =  (t – h) [de– (t + h)]
 Aj =  (t – h) (de– t - h)
 Aj =  (t-0.07125) ( de – t – 0.07125)
55

56. DESIGN FACTORS
 Nc = (Pcc / Ph) range 1.00 to 1.5
common 1.125 (19)
 Ni = (Pb / Pf) range 1.00 to 1.75
common 1.00 (20)
 Nj = (Fj / W) range 1.5 to 2.00
common 2.00 (22)
 Na = (Ym.Aj /W) range 1.5 to 2.00
common 1.75 (23)
 Aj =  (t-0.07125) ( de – t – 0.07125)
(24)
56

57. SELECTION CRITERIA
 Drilling cost
 Methods of production.
 Production rates
 Possibilities of multi-zone completions
 number of intermediate strings
 Nature of fluid to be produced
 Rig limitations
 Work over possibilities
 Availability of casings
 Common practices
 Type of well being drilled.
57

58. CASING DESIGN PRACTICE
 Arrange all the available casing pipe of the
selected size in ascending order of their
properties (Joint Strength).
 Determine or estimate expected Formation
pressure and reject all the casing pipes
having their burst resistance pressure less
than formation pressure.
58

59. CASING DESIGN PRACTICE
 Calculate Hydrostatic pressure at total
depth.
 Ph = 0.052 x Nc x m x D
 0.052 = (0.433/8.33) = Pr. Grad.Constt.
 Select the bottom most casing as first
section as per criteria Ph > Pc
59

60. CASING DESIGN PRACTICE
 Select the casing pipe for second
section which is just lighter than the
first section pipe. Calculate the pipe
setting depth-
 LS2 = PC2 / (0.052 x Nc x m )

 Calculate the load suspended below
the casing (load of first section).
 W1 = w1 x B x (D – LS2)
60

61. BUOYANCY FACTOR
 B = (65.4 - m) / 65.4
 m = Mud density in ppg
 B = (489.2 - ) / 489.2
  = Mud density in pcf
 B = (7.85 – sp.gr.) / 7.85
61

62. CASING DESIGN PRACTICE
 Calculate corrected collapse pressure of
the selected casing section.
 Pcc2 = (Pc1 / K2) [{  (K2
2 – 3W1
2)} – W1 ]
 K = 2 Ya . A A =  t ( de – t)
 . Calculated corrected setting depth of
the casing section under consideration
 LS2
II = PCC / (0.052 x Nc x m )
62

63. Check Point for Design
Criteria
 (e) Consider LS2 = LS2
ii and repeat steps
vi, vii and viii till the difference between
two calculated values of LS2 comes less
than five feet. Finalise the LS2 as lower
multiple of five and finalise the load
suspended below the section (W1).
63

64. Check Point for Design Criteria
 Calculate Maximum Allowable length of
the section under consideration-
 LM2 = [(FJ2 / NJ) – (W1 )] / w2 . B
64

65. Check Point for Design Criteria
 (a) If LM2 is greater than LS2 then Pc will
continue as design criteria for the next section
(section 3) and the pipe selected for the section
3 will be next weaker pipe than section 2.
Repeat the steps v to x for the design process of
the rest sections.
 (b) If LM2 is less than LS2 than Joint loading
will be the design criteria for the next section
(section 3) and the pipe selected for section
3 will be the next stronger pipe than
section2.
65

66. Check Point for Design Criteria
(c) Use the length of the section under
consideration as the calculated maximum
allowable length of the section-
 L2 = LM2
 and Setting depth of next section (section3)
will be
 LS3 = LS2 – L2
(d) Calculate the load up to top of the section-
 W2 = [W1 + {(LS3 – LS2) x w2 x B}]
66

67. Check Point for Design Criteria
 Repeat the steps b,c and d till the whole
depth of the well is covered.
 Report the final design in tabular form and
in graphical form
67

68. Crosscheck of casing design
 ANc = (Pcc / Ph)
 ANi = (Pb / Pf)
 ANj = (Fj / W)
 ANa = (Ym.Aj /W)
 Aj =  (t-0.07125) ( de – t – 0.07125)
68

69. Exercise
 Conventional Casing Design
69

70. Exercise Conventional Casing
Design
Design a 7 inch casing string
for a 8000 feet deep well with
12 ppg mud and 0.5 psi.ft
formation pressure gradient.
Use normal design factors for
the design.
70

71. Solution Step 1
 B = 0.6165
 PWS = 8000 x 0.5 = 4000 psi
 (All the casing pipes having Pb < 4000 Psi
are eliminated)
71

72. Step 2
Selection of Section 1
 Phd = 0.052 x 12 x 8000 x 1.125 = 5616 psi
 Section 1: 29 lbs N-80 LT&C
 LS1 = 8000 ft.

72

73. Step 3
Selection of Section 2
 Section 2: 26 lbs, N-80 LT&C K2 = 1283000 lbs.
 PC2 = 5320 psi. LS2 = 7578 ft. W1 = 9992 lbs.
 PCC2 = 5278 psi LS2I = 7518 ft. W1 = 11413 lbs.
 PCC 2 = 5272 psi LS2II = 7510ft. W1 = 11602 lbs
 PCC 2 = 5271 psi LS2III = 7509ft.
 LS2 = 7510ft. W1 = 11602 lbs
 LM2 = [(460000 / 2) – 11602] / (26 X 0.8165) = 10288 ft.
 LM2 > LS2: PC will continue as design criteria
73

74. Step 4
Selection of Section 3
 Section 3: 23 lbs. N-80 LT&CK3 = 1132000 lbs.
 PC3 = 4300 psi. LS3 = 6125 ft. W2 = 41004 lbs.
 PCC3 = 4137 psi LS3I = 5893 ft. W2 = 45929 lbs.
 PCC3 = 4116 psi LS3II = 5864ft. W2 = 46545 lbs
 PCC3 = 4113 psi LS3III = 5858ft.
 LS3 = 5860ft W2 = 46630lbs.
 LM3 = [(400000 / 2) – 46630] / (23 X 0.8165) = 8167 ft.
 LM3 > LS3: PC will continue as design criteria
74

75. Step 5 Selection of Section 4
 Section 4: 26 lbs. J-55 ST&C K4 = 981000 lbs.
 PC4 = 4060 psi. LS4 = 5783 ft. W3 = 48076 lbs.
 PCC4 = 3846 psi LS4I = 5478 ft. W3 = 53804 lbs.
 PCC4 = 3819 psi LS4II = 5440 ft. W3 = 54517lbs
 PCC4 = 3816 psi LS4III = 5435 ft. W3 = 54611 lbs
 LS4 = 5435ft W3 = 54611lbs.
 LM4 = [(345000 / 2) – 54611] / (26 X 0.8165) = 5553 ft.
 LM4 > LS4: PC will continue as design criteria
75

76. Step 6 Selection of Section 5
 Section 5: 23 lbs. J-55 ST&C K5 = 865000 lbs.
 PC5 = 3290 psi. LS5 = 4687 ft. W4 = 70490 lbs.
 PCC5 = 2989 psi LS5I = 4258 ft. W4 = 79598 lbs.
 PCC5 = 2945 psi LS5II = 4195 ft. W4 = 80935 lbs
 PCC5 = 2938 psi LS5III = 4186 ft. W4 = 81126 lbs
 PCC5 = 2937 psi LS5IV = 4185 ft. W4 = 81147 lbs
 LS5 = 4185ft W4 = 81147 lbs.
 LM5ST = [(300000 / 2) – 81147] / (23 X 0.8165) = 3666 ft.
 LM5LT = [(344000 / 2) – 81147] / (23 X 0.8165) = 4838 ft.
76

77. Step 6 Contd
 As per convention Pc can continue as
design criteria using LT & C but
 next weaker pipe 20 lb J-55 is not
available due to its lower value of burst
pressure than formation pressure.
Therefore Section 5 will be ST & C and the
design criteria will change from collapse
resistance to Joint loading strength.
 L5 = 3665 ft. W5 = 149974 lbs.
77

78. Step 7 Selection of Section 6
 Section 6: 23 lbs J-55 LT&C Fj = 344000 lbs
 LS6 = 4185 – 3665 = 520 ft. LM6 = 1173 ft.
 Since LM6 > LS6 therefore section 6 will be extended up to top.

 L6 = 520 ft. w6 = 159739 lbs.
78

79. Final Design
79
Section Casing pipe Setting Depth
Feet
Maximum
Allowable
Length (feet)
Length of
section
Feet
Load up to
top of
section.
lbs
1. 29 lbs N-80 LT&C 8000 ------ 490 11602
2. 26 lbs N-80 LT&C 7510 10288 1650 46690
3. 23 lbs N-80 LT&C 5860 8167 425 54611
4. 26 lbs J-55 LT&C 5435 5553 1250 81147
5. 23 lbs J-55 ST&C 4185 3666 3665 149974
6. 23 lbs J-55 LT&C 520 1173 520 159739

80. THANK YOU
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