project in drilling engineering

Eastern Macedonia and Thrace Institute of Technology

MSc in Oil & Gas Technology

“Drilling Engineering”

“Project in Drilling Engineering”

Iliopoulos P.

Tsiknopoulos K.

Ballis. Th.

Supervisor: Gaganis B.

June 2015

Eastern Macedonia and Thrace Institute of TechnologyMSc in Oil & Gas TechnologyDrilling Engineering

Table of Contents

Casing design..................................................................................................................................3

Axial Loading..............................................................................................................................4

Tension...................................................................................................................................5

Compression...........................................................................................................................6

Burst/Collapse............................................................................................................................7

Drill string dimensions....................................................................................................................9

HYDRAULICS.................................................................................................................................14

Hoisting system............................................................................................................................16

Appendix......................................................................................................................................18

2


Casing design

The answer to the question (5a) is included at the excel spreadsheet that was given as

an input for this project and is illustrated at the next table.

For the next question we have created the appropriate chart using the table in the

appendix which clearly shows the minimum number of casing strings needs to be placed

from top to bottom of our wellbore. In order to do so we have determine the EMD

while we have taken into account the minimum safety margin. (EMD pore + 0.5 = EMD

margin pore) and (EMD fracture -0.5 = EMD margin)

Figure 1 Mud density line

3


According to the previous chart we are able to decide about three casing strings taking

into account the initial casings (conductor, surface). So we created a model which has

five casings. Their dimensions were selected from the SPE textbook and the sample

charts that were given. Also we must take into account the corresponding mud density

and the buoyancy factor because we further want to calculate the stresses with the wet

weight.

Table 1 Casing design

Casings Depth(ft) OD Bit

CASING OD (in)

Mud Density

Buoyancy

Factor

Weight Grade

Casing ID (in)

Conductor 0 - 100 - 30 9,6 0,853 234,29 X-52 28,5

Surface casing 0 - 2000 26 20 9,6 0,853 94 H-40 19,124

1st

intermediate 0- 5800 17,5 13,375 9,6 0,853 68 C-90 12,415

2nd

intermediate 0 - 10100 12,25 9,625 15 0,771 40 C-90 8,835

Production liner

9900 - 13000 7,875 5,5 16,4 0,749 23 C-90 4,67

Axial Loading

F = ((D-L)*(Wa * BF) + Fpull)*2

Where, safety factor = 2

Wa = Casing Weight

Fpull = overpull force and BF = (1-ρmρ s

)

Ften = π4 σyield (OD2 – ID2)

4


Tension

Conductor

F = ((100 * 234.29 * 0.853) + 10000) * 2 = 59969.9 lbf

Ften = π/4 * 52000*(302 – 28.5 2) = 3583771.8 lbf

Ften > F Can withstand the stress

Surface casing

F = ((2000 * 94 * 0.853) + 10000) * 2 = 340728 lbf

Ften = π/4 * 40000*(202 – 19.1242) = 1076706.2 lbf


1 st intermediate

F = ((5800 * 68 * 0.853) + 10000) * 2 = 692846.4 lbf

Ften = π/4 * 90000*(13,3752 – 12.4152) = 1750068.17 lbf


2 st intermediate

With H-40

F = ((10100 * 32.3 * 0.771) + 10000) * 2 = 523046.7 lbf

Ften = π/4 * 40000*(9.625 2 – 9.0012) = 365.135 lbf

Ften < F Cannot withstand the stress

With C-90

F = ((10100 * 40 * 0.771) + 10000) * 2 = 642.968 lbf

Ften = π/4 * 90000*(9.625 2 – 8.835 2) = 1030839.8 lbf


Production liner

F = ((3100 * 23 * 0.749) + 5000) * 2 = 116807.4 lbf

Ften = π/4 * 90000*(5.52 – 4,672) = 596666.2 lbf

5



Compression

Conductor

F = 100 * 234.29 = 23429 lbf

Ften = π/4 * 52000*(302 – 28.5 2) = 3583771.8 lbf


Surface casing

F = 2000 * 94 = 188000 lbf

Ften = π/4 * 40000*(202 – 19.1242) = 1076706.2 lbf


1 st intermediate

F = 5800 * 68 = 394400 lbf

Ften = π/4 * 90000*(13,3752 – 12.4152) = 1750068.17 lbf


2 st intermediate

With H-40

F = 10100 * 32.3 = 326230 lbf

Ften = π/4 * 40000*(9.625 2 – 9.0012) = 365.135 lbf

Ften < F Can withstand the stress

With C-90

F = 10100 * 40 = 404000 lbf

Ften = π/4 * 90000*(9.625 2 – 8.835 2) = 1030839.8 lbf


Production liner

F = 3100 * 23 = 71300 lbf

Ften = π/4 * 90000*(5.52 – 4.672) = 596666.2 lbf


6


After the above calculations we conclude that instead of using H-40 type to the 2 st

intermediate casing, we use C-90.The worst case scenario is obviously on tension loadings.

Burst/Collapse

We assume a gas density of 3 ppg in case of a kick.

Internal pressure: Pi = 0.052 * ρgas * L

Maximum burst pressure: Pbr = 0.875 2t σ yielddn

External pressure: Pf = 0.465 * Depth

Table 2 Burst calculations

Depth (ft) Pe (psi) Pff (psi) Pi (psi)

Burst Pressure

(psi)

Max Pburst (psi)

Result

Surface casing0 0 998,4 686,4 686,4

1530 Accept2000 930 998,4 998,4 68,4

1st Intermidiate casing

2000 930 4575,272 3982,472 3052,472

5652 Accept4000 1860 4575,272 4294,472 2434,472

5800 2697 4575,272 4575,272 1878,272

2st Intermidiate casing

5800 2697 8734,076 8063,276 5366,276

6464 Accept8000 3720 8734,076 8406,476 4686,476

10100 4696,5 8734,076 8734,076 4037,576

Production Liner 9900 4603,5 11573,12 11089,52

6486,02 11884 Accept

7


10100 4696,5 11573,12 11120,72 6424,22

13000 6045 11573,12 11573,12 5528,12

Table 3 Stress combination

Depth (ft)

Inner P Outer PAxial Load

AreaAxial stress

σt termσz

termellipse result

0 14,7 0 188000 26,91766 6984,263 0,008578 0,175 0,02922000 14,7 998,4 0 26,91766 0 -0,57404 0,0004 0,32972000 14,7 998,4 258400 19,4452 13288,63 -0,15795 0,1478 0,07014000 14,7 1996,8 122400 19,4452 6294,612 -0,31826 0,0701 0,12855800 14,7 2895,36 0 19,4452 0 -0,46253 0,0002 0,2145800 14,7 4524 172000 11,45378 15016,88 -0,63656 0,167 0,53948000 14,7 6240 84000 11,45378 7333,826 -0,8788 0,0817 0,850710100 14,7 7878 0 11,45378 0 -1,11003 0,0002 1,23239900 14,7 8442,72 71300 6,629624 10754,76 -0,67118 0,1197 0,545110100 14,7 8613,28 66700 6,629624 10060,9 -0,68476 0,112 0,558113000 14,7 11086,4 0 6,629624 0 -0,88171 0,0002 0,7776

Production Liner

Accept

Accept

Unaccept

Accept

1st Intermidiat

e casing2st

Intermidiate casing

Surface casing

Stress Combination

After completing the previous calculations we found out that our second intermediate

casing cannot withstand the total load according to the elliptic equation.

According to the given formula: σz term2 + σt term2 - σt term2* σz term2 >1 So we

conclude to change the dimensions of that casing from C-90 to C-95.

Table 4 New casing design

Casings Depth(ft) OD Bit

CASING OD (in)

Mud Densit

y

Buoyancy

Factor

Weight

Grade Casing ID (in)

Conductor 0 - 100 - 30 9,6 0,853 234,29 X-52 28,5

Surface casing

0 - 2000 26 20 9,6 0,853 94 H-40 19,124

1st

intermediate0- 5800 17,5 13,375 9,6 0,853 68 C-90 12,415

8


2nd

intermediate0 -

1010012,2

59,625 15 0,771 40 C-95 8,835

Production liner

9900 - 13000

7,875

5,5 16,4 0,749 23 C-90 4,67

Drill string dimensions

Table 5 Given data

Specifications OD ID weight Steel density

Drill pipe 5’’ 4,276’’ 19,5lbf/ft 490lbm/ft3

Drill collars 5’’ 2,5’’

Having into account all the given specifications for drill pipe and drill collars, it is

absolutely necessary to determine the suitable lengths. These lengths should ensure

that during the drilling process any point of drill pipe is not under compression and any

point of drill collars is not under tension. Different WOB at three stages, give us detailed

information in order to locate exactly the point (neutral point) above which there is not

tendency to buckling. The correct position which satisfies the previous restrictions is the

top of the collars.

EQUATIONS

Minimum drill collars length: Ldc= Fb/Wdc*BF

Stability force: Fs(depth)= AiPi-AoPo

Wdc = π/4(OD2-ID2)

Ft=Wdp*Ldp+Wdc*Ldc+0,052*ρmud*(D-Ldc)*(Adc-Adp)-0,052*ρmud*D*Adc-WOB

9


BF = 1 – Mud density65,5lbm /gal

Where:

OD,ID= external and internal diameter

Pi= internal pressure

Po=external pressure

Fb=WOB

65,5= weigth og a gallon of steel

Calculations

Wdc=π/4*((52−2,52)/0,2945)=50,1lbf/ft

490lbm/ft3=65,5lb/gal

For 5800ft

BF = 0,853

L=Fb

Wdc(1− PfPs

)=Fb

Wdc∗BF= 25000 lbf50,1∗0,85= 587ft = 590ft

For 10100ft

BF=0,771

L = Fb

Wdc (1− PfPs

) =Fb

Wdc∗BF= 50000lbf

50,1 lbfft

∗0,77= 769ft=770ft

For 13000ft

BF=0,749

L =Fb

Wdc(1− PfPs

)=Fb

Wdc∗BF= 75000 lbf

50,1 lbfft

∗0,749 = 1999ft=2000ft

The previous calculations were conducted using an outer drill collar diameter equal to

5’’. Using Wdc=50,1lbf/ft and the above minimum drill collars lengths at the excel file

10


we observed that a larger OD collar is required, in order to avoid any segment of our

drill pipe to be under compression. So we selected a collar with OD equal to 8’’.

Unfortunately the suitable ID diameter of our production liner is equal to 4.67’’, but

using this ID we can’t use any of the previous collar diameters. In order to proceed

with tis project we assume an OD of the drill collars equal to 8’’.

New Wdc = 155 lbf/ft

For 5800 buckling

11


-200000 -100000 0 100000 2000000

1,000

2,000

3,000

4,000

5,000

6,000

7,000

Axial forces, lbfD

epth

, ft

For 10100 buckling

12


-600000 -400000 -200000 0 200000 4000000

2,000

4,000

6,000

8,000

10,000

12,000

Axial forces , lbf

Dep

th,

ft

For 13000 buckling

13


-1000000 -500000 0 5000000

2,000

4,000

6,000

8,000

10,000

12,000

14,000

Axial forces, lbf

Dep

th, f

t

Grade of the drill pipes

14


The following formula give us the opportunity to select the suitable grades of drill pipes while includes the wet weight of drill string an over pulling force at all depths

F’t= (Wcd*Ldc+Wdp*Ldp)*BF+ pulling force

σi= F’t/A

Where : σι > σyield

Table 6 Drill string dimensions and specifications

DEPTH WOB Ldc Ldp Ft(lbf) GRADES

5800 25000 590 5210 264667 D-55

10100 50000 770 9330 332290 E-75

13000 75000 2000 11000 492850 X-95

HYDRAULICS

EQUATIONS

For the calculations we assumed a sphericity ψ = 0.801, the mean diameter of the

cuttings equal to 0.0025”.

The flow rate is 400 gal/min

Slip velocity using stokes model: Us =138( ps−pf )d2

μ

Annular velocity: Ua =q

2.448∗(d2−d2)

pipe velocity: Udp =q

2.448∗d2

total nozzle area: At = 3*π/4*(13/32)

15


Δpbit =8.311∗10−5∗p∗q2

cd2∗A tot

2

Neutonian friction pressure loss

There exist several rheological fluids models such as Bingham Plastic Model, Power Law

Mode, Robertson-Stuff Model and Herschel-Bulkley Model using fluid hydrodynamics.

Some of them are utilized to characterize drilling fluids while some are not applicable to

drilling fluids. In this assignment we assume that the drilling mud is a Newtonian fluid.

Pipe: dPfdL

= μ v1500d2

Annulus: dPfdL

= μ v1500(d¿¿2−d1)

2¿

Mud pump pressure: Ppwp = Ps + Pd + Pa + Pd, where Ps is the Surface equipment pressure loss and we assume that is equal to zero.

Table 7 Required pump pressure

DepthU

annulus pipe

U anullu

s collar

Udp UdcAt

nozzleInitial slip U

F Nre New FFinal slip U

Pressure loss DPbit

Pressure loss

Dppipe

Pressure loss

Dpanullus

Recuired pump

pressure Ppwp

0-2000 0.48 0.54 8.94 26.14 0.33 0.21 2.59 9.27 170.00 0.03 1289.71 6.34 0.17 1296.212000-5800

1.27 1.81 8.94 26.14 0.33 0.21 2.59 9.27 170.00 0.03 1289.71 16.71 7.63 1314.05

5800-10100

3.08 11.62 8.94 26.14 0.33 0.11 3.00 7.99 200.00 0.01 2015.16 25.94 1141.54 3182.64

10100-13000

4.41 17.56 8.94 26.14 0.33 0.09 3.48 6.90 230.00 0.01 2203.25 45.81 1300.00 3549.05

All the above calculations have been conducted with a viscosity of 5 cp, so that the mud

velocity is always greater than the slip velocity at all different depths.

16


Hoisting system

At this stage we should compute the maximum expected load which stresses the

hoisting system during the drilling process. We consider two different scenarios for the

drill string and casing strings, while we assume an extra pull load of 20000 psi and

10000 psi respectively.

Table 8 Maximum load from drill string

Depth (ft)

Pipe (ft)Weight (lbf/ft)

Collars (ft)

Weight (lbf/ft)

Total pipe (lbf)

Total collar (lbf)

Mud (ppg)

Extra Pull load (lbf)

Wet weight

(lbf)

Total weight (lbf)

2000 1750 250 155 34125 38750 9.6 20000 62194.08 82194.08

5800 5210 590 155 101595 91450 9.6 20000 164751.38 184751.38

10100 9930 770 155 193635 119350 15 20000 241309.05 261309.05

13000 11000 2000 155 214500 310000 16.4 20000 393174.81 413174.81

19.5

Table 9 Maximum load from casings

Depth (ft)

Weight (lbf/ft)

Weight (lbf/ft)

Weight (lbf/ft)

Total casing (lbf)

Mud (ppg)

Extra Pull load (lbf)

Wet weight

(lbf)

Total weight

(lbf)2000 19.5 155 94 188000 9.6 10,000 160446 170446

5800 19.5 155 68 394400 9.6 10,000 336595 346595

10100 19.5 155 40 404000 15 10,000 311481 321481

13000 19.5 155 23 299000 16.4 10,000 224136 234136

The red boxes in the above tables indicate the maximum load in each case that the

hoisting system is able to withstand.

Minimum number of lines

Ff=(W*1,6)/(n*E)<=Fmax E*n=> (W*1,6)/(Fmax)

Where: n: number of lines between the crown and the traveling block

E: efficiency of hoisting system

W: maximum hoisting load of 413174.81lbf.

For E=0,874 and n=6 the inequality is satisfied.

17


Time required to pull 90 ft

Max hook power: Ph = Pd * E = 500 hp *0.874 = 437 hp

Max hoisting speed: v = Ph / W = (437 / 413174.81) * 33000 = 34.9 ft/min

Time required: t = s / v = 90 ft / 34.9 ft/min = 2.57 min

18


Appendix

Table 10 Safety margins

EMD (lb/ft3) MarginPore Fracture Depth Pore Fracture8.95 13.71 2100 9.45 13.218.95 13.77 2200 9.45 13.278.95 13.83 2300 9.45 13.338.95 13.90 2400 9.45 13.408.95 13.96 2500 9.45 13.468.95 14.02 2600 9.45 13.528.95 14.08 2700 9.45 13.588.95 14.14 2800 9.45 13.648.95 14.20 2900 9.45 13.708.95 14.25 3000 9.45 13.758.95 14.31 3100 9.45 13.818.95 14.37 3200 9.45 13.878.95 14.43 3300 9.45 13.938.95 14.48 3400 9.45 13.988.95 14.54 3500 9.45 14.048.95 14.59 3600 9.45 14.098.95 14.65 3700 9.45 14.158.95 14.70 3800 9.45 14.208.95 14.75 3900 9.45 14.258.95 14.81 4000 9.45 14.318.95 14.86 4100 9.45 14.368.95 14.91 4200 9.45 14.418.95 14.96 4300 9.45 14.468.95 15.01 4400 9.45 14.518.95 15.06 4500 9.45 14.568.95 15.11 4600 9.45 14.618.95 15.16 4700 9.45 14.668.95 15.21 4800 9.45 14.718.95 15.26 4900 9.45 14.768.95 15.31 5000 9.45 14.818.95 15.35 5100 9.45 14.858.95 15.40 5200 9.45 14.908.95 15.45 5300 9.45 14.958.95 15.49 5400 9.45 14.998.95 15.54 5500 9.45 15.048.95 15.58 5600 9.45 15.088.95 15.63 5700 9.45 15.138.95 15.67 5800 9.45 15.178.95 15.71 5900 9.45 15.218.95 15.76 6000 9.45 15.268.95 15.80 6100 9.45 15.308.95 15.84 6200 9.45 15.348.95 15.88 6300 9.45 15.388.95 15.92 6400 9.45 15.428.95 15.97 6500 9.45 15.478.95 16.01 6600 9.45 15.518.95 16.05 6700 9.45 15.55

19


8.95 16.09 6800 9.45 15.598.95 16.13 6900 9.45 15.638.95 16.16 7000 9.45 15.668.95 16.20 7100 9.45 15.708.95 16.24 7200 9.45 15.748.95 16.28 7300 9.45 15.788.95 16.32 7400 9.45 15.828.95 16.35 7500 9.45 15.858.95 16.39 7600 9.45 15.898.95 16.43 7700 9.45 15.938.95 16.46 7800 9.45 15.968.95 16.50 7900 9.45 16.008.95 16.53 8000 9.45 16.036.96 16.52 8100 7.46 16.027.00 16.45 8200 7.50 15.957.05 16.40 8300 7.55 15.907.08 16.59 8400 7.58 16.097.06 16.60 8500 7.56 16.107.03 16.51 8600 7.53 16.017.29 16.52 8700 7.79 16.027.55 16.53 8800 8.05 16.037.80 16.94 8900 8.30 16.448.26 16.76 9000 8.76 16.268.54 16.76 9100 9.04 16.268.65 16.71 9200 9.15 16.218.85 16.68 9300 9.35 16.18

10.37 16.89 9400 10.87 16.3910.79 16.90 9500 11.29 16.4011.52 16.91 9600 12.02 16.4112.10 16.94 9700 12.60 16.4412.81 16.98 9800 13.31 16.4813.89 17.05 9900 14.39 16.5514.24 17.09 10000 14.74 16.5914.56 17.13 10100 15.06 16.6314.77 17.18 10200 15.27 16.6814.94 17.22 10300 15.44 16.7215.15 17.25 10400 15.65 16.7515.34 17.27 10500 15.84 16.7715.50 17.30 10600 16.00 16.8015.60 17.33 10700 16.10 16.8315.65 17.35 10800 16.15 16.8515.70 17.38 10900 16.20 16.8815.75 17.41 11000 16.25 16.9115.80 17.43 11100 16.30 16.9315.84 17.45 11200 16.34 16.9515.88 17.45 11300 16.38 16.9515.90 17.46 11400 16.40 16.9615.92 17.48 11500 16.42 16.9815.94 17.49 11600 16.44 16.9915.96 17.50 11700 16.46 17.0015.97 17.51 11800 16.47 17.0115.98 17.52 11900 16.48 17.0215.99 17.53 12000 16.49 17.0316.00 17.54 12100 16.50 17.04

20


16.00 17.55 12200 16.50 17.0516.00 17.56 12300 16.50 17.0616.01 17.57 12400 16.51 17.0716.01 17.58 12500 16.51 17.0816.02 17.59 12600 16.52 17.0916.02 17.60 12700 16.52 17.1016.03 17.61 12800 16.53 17.1116.03 17.62 12900 16.53 17.1216.04 17.62 13000 16.54 17.12

21

project in drilling engineering

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