Experimental Model Study of Liquid–Liquid and Liquid–Gas ...
Modelling Gas Well Liquid (Un)Loading - Artificial lift€¦ · Gas Well Deliquification Workshop...
Transcript of Modelling Gas Well Liquid (Un)Loading - Artificial lift€¦ · Gas Well Deliquification Workshop...
Gas Well Deliquification WorkshopAdams Mark Hotel, Denver, Colorado
February 25 - 27, 2008
Modelling Gas Well Liquid (Un)LoadingKees Veeken (NAM, Assen)Murat Kerem (Shell, Rijswijk)
Feb. 25 - 27, 2008 2008 Gas Well Deliquification Workshop Denver, Colorado
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Objectives of Modelling
• Liquid loading– Improve capacity forecast to maximise nomination– Determine proven and expectation reserves– Predict end of field life i.e. abandonment date– Predict date that deliquification should be installed
• Liquid unloading (a.k.a. deliquification)– Determine SFR and reserves at stake– Generate incremental forecast to justify investment– Select best (sequence of) deliquification measures– Optimise deliquification techniques and implementation
Feb. 25 - 27, 2008 2008 Gas Well Deliquification Workshop Denver, Colorado
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Contents
• Objectives• Well & reservoir model• Abandonment pressure & ultimate recovery• Production forecast for deliquification• Minimum gas rate & metastable production• Gas well unloading• Future modelling
Feb. 25 - 27, 2008 2008 Gas Well Deliquification Workshop Denver, Colorado
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• Cullender-Smith
• Forcheimer
• Turner
• Abandonment
FBHP = FTHP + HH + FF:FBHP2 = B.FTHP2 + C.Q2
Pres = FBHP + DD:Pres
2 – FBHP2 = A.Q + F.Q2
Q = Qmin:Pab
2 = B.FTHP2 + A.Qmin+ (C+F).Qmin2
Qmin = TC.FTHP0.5.ID2/[(FTHT+273).Z]
FTHP
A & F
DrawdownFBHP Pres
Hydrostatic
Head,
Fluid Friction &M
inimum
Rate
B &
C, Q
min
Well Model
Feb. 25 - 27, 2008 2008 Gas Well Deliquification Workshop Denver, Colorado
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Turner
0
50
100
150
200
250
300
0 20 40 60 80 100
FTHP (bar)
Qm
in (e
3 m3 /d
)
2 7/8" 3 1/2" 5" 7"
Feb. 25 - 27, 2008 2008 Gas Well Deliquification Workshop Denver, Colorado
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Abandonment Pressure & Reserves
Pres
UR GIIPGp
Pab
Pi UR = GIIP x (Pi – Pab) / Pi
Feb. 25 - 27, 2008 2008 Gas Well Deliquification Workshop Denver, Colorado
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Wellhead Pressure & Tubing Size
0
40
80
120
160
0 50 100 150 200
A (bar2/103 m3/d)
P ab (
bar)
3-1/2", 10 bar FTHP
5", 10 bar FTHP
3-1/2", 50 bar FTHP
5", 50 bar FTHP
TightProlific
Com
pres
sion Ve
loci
ty S
trin
g
Compression benefit for all AVelocity string benefit increases with A
Feb. 25 - 27, 2008 2008 Gas Well Deliquification Workshop Denver, Colorado
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Stim., Foam, Gas Lift, Plunger & Pump
0
40
80
120
160
0 50 100 150 200
A (bar2/103 m3/d)
P ab (
bar)
TC=0 TC=100 TC=200 TC=285
Gas
Lift
Foam
Stimulation
Pum
p
Plun
ger
Stimulation increases reservesFoam lift benefit increases with A
Feb. 25 - 27, 2008 2008 Gas Well Deliquification Workshop Denver, Colorado
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Prolific Gas Well (Low A)
GIIP = 109 m3, A = 4 bar2/(103 m3/d), 5" tubing
0
1000
2000
3000
4000
0 1 2 3 4 5Time (yrs)
Gas
Rat
e (1
03
m3 /d
)
0
250
500
750
1000
Gas
Vol
ume
(106
m3 )
Base Case Compression Foamer Gas LiftBase Case Compression Foamer Gas Lift
77% 22% 1% 1%
Feb. 25 - 27, 2008 2008 Gas Well Deliquification Workshop Denver, Colorado
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GIIP = 109 m3, A = 4 bar2/(103 m3/d), 5" tubing
0
1000
2000
3000
4000
0 200 400 600 800 1000Gas Volume (106 m3)
Gas
Rat
e (1
03 m3 /d
)
Base Case Compression Foamer Gas Lift
77% 22% 1% 1%
Prolific Gas Well (Low A)
Compression/eductor most usefulReduced scope for other measures
Feb. 25 - 27, 2008 2008 Gas Well Deliquification Workshop Denver, Colorado
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Tight Gas Well (High A)
GIIP = 106 m3, A = 400 bar2/(103 m3/d), 5" tubing
0
100
200
300
400
0 4 8 12 16 20Time (yrs)
Gas
Rat
e (1
03
m3 /d
)
0
250
500
750
1000
Gas
Vol
ume
(106
m3 )
Base Case Compression Foamer Gas LiftBase Case Compression Foamer Gas Lift
37% 32% 21% 10%
Feb. 25 - 27, 2008 2008 Gas Well Deliquification Workshop Denver, Colorado
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Tight Gas Well (High A)
GIIP = 106 m3, A = 400 bar2/(103 m3/d), 5" tubing
0
100
200
300
400
0 200 400 600 800 1000Gas Volume (106 m3)
Gas
Rat
e (1
03 m3 /d
)
Base Case Compression Foamer Gas Lift
37% 32% 21% 10%
Deliquification critical for recoveryScope for wide range of measures
Sharing the same cakeSelection is key
Feb. 25 - 27, 2008 2008 Gas Well Deliquification Workshop Denver, Colorado
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Tight Gas – Outflow Challenge
0%
20%
40%
60%
80%
100%
0.1 1 10 100 1000KH (mD.m)
RF
(%)
2-7/8” tubingTHP 5 bar
H 100m, 1xRF=0% if K < 10 µD
Gas well deliquificationessential to maximise recovery
for tight gas wells
Outflow as challenging as inflow!
Feb. 25 - 27, 2008 2008 Gas Well Deliquification Workshop Denver, Colorado
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Minimum Rate Actual & Turner
0
5
10
15
20
25
<1.0 1.0-1.5 1.5-2.0 2.0-2.5 >2.5Actual minimum rate / Turner criterion (-)
Num
ber o
f Wel
ls (-
)
Feb. 25 - 27, 2008 2008 Gas Well Deliquification Workshop Denver, Colorado
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y = 3.4441x-0.1717
R2 = 0.2085
0.0
0.5
1.0
1.5
2.0
2.5
3.0
3.5
4.0
0 200 400 600 800 1000
A0.5 x FTHP
Act
ual/T
urne
r (-)
Modified Turner
Well more sensitive topressure fluctuations at low pressure
Feb. 25 - 27, 2008 2008 Gas Well Deliquification Workshop Denver, Colorado
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Turner Literature Data
0
2
4
6
8
10
12
0 1 2 3 4 5 6 7
Calculated Loading Rate (Mscf/d)
Act
ual G
as R
ate
(Msc
f/d)
Unloaded Loaded Questionable 1:1 1:1.5 Success Failure
Feb. 25 - 27, 2008 2008 Gas Well Deliquification Workshop Denver, Colorado
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Dependency on A in Simulator
Qmin increases as A decreases
Prolific
Qgas
FTH
P
Poor
Well more sensitive topressure fluctuations at low pressure
Feb. 25 - 27, 2008 2008 Gas Well Deliquification Workshop Denver, Colorado
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Model Limitations
• Underestimates hydrostatic head– Calculated abandonment pressure too low– Uplift when injecting foam just above critical rate (?)
• No recharging due to tight or slow gas– Connected volume increases with time– Intermittent production
• Monobore only i.e. no wet foot across larger liner– Extra back pressure
• No metastable flow
Feb. 25 - 27, 2008 2008 Gas Well Deliquification Workshop Denver, Colorado
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0
20000
40000
60000
80000
29-Dec 18-Jan 7-Feb 27-Feb 19-Mar 8-Apr
Gas
Rat
e (m
3/d)
0
10
20
30
40
THP,
BH
P (b
ar)
Gas Rate THP BHP
Metastable Gas Production
Gas bubbles through liquid column (SPE 95282)Stable rate 40,000 m3/d
Metastable rate 12,000 m3/d
Feb. 25 - 27, 2008 2008 Gas Well Deliquification Workshop Denver, Colorado
2024/04/2006 08:03:12 23/07/2006 08:03:1290.00 Day(s)
MILJ.NM3/D BARG DEG.CELC.
0.1
0.2
0.3
0.4
0.5
0.6
0.7
0
0.8
-10
70
-120
80 MILJ.NM3/D BARG DEG.CELC.
Qm
in=
180,
000
m3 /d
Metastable Gas ProductionOffshore wellhead temperature provides indication of
liquid loading & metastable production
Feb. 25 - 27, 2008 2008 Gas Well Deliquification Workshop Denver, Colorado
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• Gas well unloads far below Turner criterion• Initial unloading via piston like displacement• Critical velocity of Taylor gas bubble 10x lower than
Turner critical velocity
• Piston model• OLGA multiphase dynamic flow simulator
Unloading Gas Well
Feb. 25 - 27, 2008 2008 Gas Well Deliquification Workshop Denver, Colorado
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FTHP Model vs Actual
0
50
100
150
200
250
0 60 120 180 240 300 360 420 480
Time (min)
FTH
P (b
ar),
Cho
ke (1
/64"
)
0E+00
1E+05
2E+05
3E+05
4E+05
5E+05
Gas
Rat
e (m
3 /d)
FTHP Actual FTHP Piston FTHP OLGA Choke Gas Rate
Unloading Well with 7” TubingQmin,water ~4E5 m3/d, Qmin,condensate ~2E5 m3/d
Gas @ surface
Liq @ surface
Feb. 25 - 27, 2008 2008 Gas Well Deliquification Workshop Denver, Colorado
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Volume Fraction @ 240 min (OLGA)
0.0
0.2
0.4
0.6
0.8
1.0
0 500 1000 1500 2000 2500 3000 3500
Along Hole Distance from Toe (m)
Frac
tion
(-)
Oil Based Mud Completion Brine Base Oil
Qgas ~4E4 m3/d
Feb. 25 - 27, 2008 2008 Gas Well Deliquification Workshop Denver, Colorado
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Volume Fraction @ 480 min (OLGA)
0.0
0.2
0.4
0.6
0.8
1.0
0 500 1000 1500 2000 2500 3000 3500
Along Hole Distance from Toe (m)
Frac
tion
(-)
Oil Based Mud Completion Brine Base Oil
Qgas ~4E5 m3/d
Feb. 25 - 27, 2008 2008 Gas Well Deliquification Workshop Denver, Colorado
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Future Modelling
• Liquid loading– Update & upgrade modified Turner – Resolve abandonment pressure discrepancy– Support multiphase dynamic modelling of liquid loading
• Liquid unloading (a.k.a. deliquification)– Model interaction between reservoir and well in liquid
loading domain to produce better deliquification forecasts & to optimise deliquification techniques
Feb. 25 - 27, 2008 2008 Gas Well Deliquification Workshop Denver, Colorado
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