Lateef Akanji

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Introduction Conceptual gas lift design Variables

Pressure GLGIR Water cut

Results Conclusion

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Long string High PI High BHFP Excessive water production

Short string Low PI Low BHFP Excessive water production

Artificial lift is critical in maximising oil production within the limits of the facility where the rates are constrained by pressure excessive water production available lift gas

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Key variables examined include:

gas lift gas injection rate (GLGIR)

water cut

tubing sizes

erosional velocity

pressure versus rate

4

5

7199ft

85ft

7256ft

7160ft

7307ft

7506ft

8083ft

8328ft

9857ft

6

Table 1 SS LS

Casing (10-3/4) MD (ft.) 9953

End of tubing, MD (2-3/8 in.) (ft.) 7307 8083

Packer depth, MD (ft.) 7160 7160 & 7506

Perforation MD (ft.) 7486-7498 8124 - 8130

Maximum depth for a gas lift mandrel MD (ft.)

4321 4238

Reservoir temperature (oF) 155 169

Table 2: Fluid properties

Variable LS SS

oAPI gravity

g

w

20.49 0.654 1.02

24.85 0.654 1.00

Pb (psia) Water cut (%) Rp (Scf/STB) Rs (Scf/STB)

3008 50

380 380

3208 50

422

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Table 3: Reservoir data

Variable LS SS

Static pressure (oF) 2680 2410

Temperature (oF) 169 155

Liquid, PI (J) (STB/D-psi) 3 0.45

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Table 4: Production data

Variable LS SS

FWHT (oF) FWHP (psig) Sep. press. (psig)

100 165 48

97 135 48

Flow line length (ft.) Flow line size ID (in.)

1673 4

1673 4

Table 5: Well test data

Variable LS SS

qtotal(bbl/D) qo(bbl/D) Qw(bbl/D) qp,t

qg/qg,t(%) GLR (scf/bbl)

729 425 275 0.85 20

1169

533 324 209 533 74 357

FBHP (psia) FWHT (oF)

2423 82

2174 87

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Table 6: Gas lift system

Variable LS SS

Pkickoff (psig) Pinj (psig) Min valve inj. ∆P (psi) Unloading grad. (psi/ft.) Unloading WHP (psig)

820 820 101

0.433 150

820 820 100

0.433 120

g,inj

qinj(MMScf/D) qmax,inj(MMScf/D) Tsurf,inj(

oF)

0.65 0.68

1 89

0.654 0.05 0.77 89

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wfres

R

wf

R

wf

PP

qJ

P

P

P

P

q

q

2

8.02.01'

IPR equation (Vogel, 1968)

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h

g

v

D

Mfq c

m

m

m

Lm

2

109652.2h

P 144

2

511

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LgLLm HH 1

Tubing correlation, (Hagedorn and Brown, 1965)

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fV

w8

f is friction factor

ρ is stream density (kg/m3)

V is stream velocity (m/s)

Ʈw is shear stress (N/M2)

cV max

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wwwo f+) f-(1 = l

wowo f)-(+= l

fw is water cut

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0

150

300

450

0

2.5

5

7.5

10

0 1000 2000 3000

Oil Viscosity (cp)

GOR (scf/STB)

Fig. 1: PVT plots showing the variation of μo and Rs

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200

400

600

0.2 0.6 1

Oil r

ate

ST

B/D

Gaslift gas injection rate (MMScf/D)

2.38" 2.88" 3.5"

Tubing sizes

Fig. 2: Typical oil rate versus GLGIR for varying tubing sizes of 2-3/8”, 2-7/8”, 3-1/2”

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10

110

210

310

0 0.5 1 1.5

Gaslift gas injection rate (MMScf/D)

WC = 0%

WC = 10%

WC = 50%

WC = 80%

Oil r

ate

ST

B/D

Fig. 3: Typical oil rate versus GLGIR at different water-cuts and 2-3/8” tubing. The optimal value is indicated by the arrow.

Heavier gas requires Lower surface pressure

Higher injection rate per barrel of fluid lifted

Higher compression horsepower

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Table 7: Summary of the sensitivity on well A2 performance

GLGIR (MMScf/day) Water-cut (%) Tubing size ID

(inches)

SS LS SS LS SS LS

0.05 0.4 0 0 2

0.4125 0.7 10 10 2 3/8 2 3/8

0.775 0.85 50 50 3 2 7/8

1.1375 1.0 80 77.5 3 ½ 3 ½

1.5 100 100

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Table 8: Sensitivity on well A2 performance SS

Water cut (%) 0 10 50 80

Liquid rate (STB/day) 378.6 375.0 340.3 281.1

Oil rate (STB/day) 378.6 337.5 170.1 56.2

Pressure (psig) 1499.9 1525.3 1670.5 1832.7

Table 9: Sensitivity on well A2 performance LS

Water cut (%) 10 50

Liquid rate (STB/day) 813.8 425.6

Oil rate (STB/day) 732.4 263.8

Pressure (psig) 2520 2570

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Liquid rate (STB/D)

Pre

ssure

(psig

)

Liquid rate (STB/D)

Fig. 4: IPR/VLP plots for SS at 10% WC Fig. 5: IPR/VLP plots for SS at 50% WC

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Liquid rate (STB/D)

Pre

ssure

(psig

)

Liquid rate (STB/D)

Fig. 6: IPR/VLP plots for LS at 10% WC for tubing sizes of 2-3/8”, 2-7/8”, 3-1/2”; the green marks indicate erosional velocity limits

Fig. 7: IPR/VLP plots for LS at 50% WC tubing sizes of 2-3/8”, 2-7/8”, 3-1/2”; the green marks indicate erosional velocity limits

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0

500

1000

1500

2000

2500

3000

0 100 200 300 400 500 600 700 800

Pre

ssure

(p

sig

)

Oil rate (STB/D)

VLP curve (Optimal)

IPR curve (optimal)

VLP curve (current)

IPR curve (current)

Fig. 8: Performance plots comparison; current and optimal, for the SS

0

1000

2000

3000

4000

5000

6000

0 1000 2000 3000 4000 5000

Pre

ssure

(p

sig

)

Oil rate (STB/D)

IPR curve (Optimal)

VLP curve (Optimal)

IPR curve (current)

VLP curve (current)

Fig. 9: Performance plots comparison; current and optimal, for the LS

An accurate dual completion gas-lift simulation model was designed to determine the optimum gas lift gas injection (GLIR ) rate

the optimal production rates

In the short string production increase of 53% was achieved with an optimum

GLGIR of 0.775 MMScf/Day at the current 50% water-cut

production can be further increased by up to a factor of 4 if the water cut can be curtailed

In the long string production was increased by 39% with an optimal GLGIR of 1

MMScf/Day at the current 50% water-cut

curtailing the water production will further increase the production by up to a factor of 3

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Incorporate the effects of well instabilities associated with casing heading

density wave oscillation

dynamic mixing (reservoir fluid/ injected gas)

Smart gas lift design automatic gas lift mandrel positioning

variable intelligent port size

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A. Hagedorn and K. Brown, “Experimental Study of Pressure Gradients Occurring During Continuous Two-Phase Flow in Small Diameter Vertical Conduits.” Journal of Petroleum Technology Volume 17, Number 4, pages 475-484, (1965).

J. V. Vogel, “Inflow performance relationships for solution gas drive wells. Journal of Petroleum Technology.” Volume 20, Number 1 pages 83-92 (1968).

Petroleum Experts Prosper Manual. (2010). Single Well Systems Analysis, Version 11.5.

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PTRG

PETEX

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THANK YOU

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