lecture12a_basic gaslift sec 4 - unloading
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7/28/2019 Lecture12a_Basic Gaslift Sec 4 - Unloading
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Gas Lift
Production Optimisation
Lecture 12a: Gas Lift - Section 4
ecommen e ex : r c a e o s,
Kermit E. Brown, Volume 2a
PennWell Publishing Co, Tulsa, OK, 1980
Akim Kabir
Senior Lecturer
Department of Petroleum Engineering
Curtin University of Technology
Slide 1Section 4 – Continuous Flow Design
Aug 2008
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Gas Lift
PRESSURE (PSI)
Fluid Level500
0500 10000
CASING
PRESSURE Casing pressure
Mandrel
Depths
V D ) 1000
P T H
( F T
1500
2000
Static radient
D E
2500
Flowing gradient
3500
H P
H P
Slide 2Section 4 – Continuous Flow Design
S I B
F B
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Gas Lift
Pressure Profiles in Continuous Flow
PRODUCED FLUIDCASING
PRESSURE, Pc
TUBING
PRESSURE, Pt
Pwh
Pcs
INJECTION GAS
PRESSURE (PSI)
0500 10000
Dummy D E P T H
Valve 1
Valve 2
D
Valve 3
Valve 4
Valve 5
I B H P
Point of BalancePoint of Gas
Injection
B H P
Slide 3Section 4 – Continuous Flow Design
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Gas Lift
Wh so man Gas Lift Valves?
No Gas Injection - Well Dead
PRESSURE (PSI)
Fluid Level ---->
500
0
CASINGPRESSURE
• More hardware meansmore $ and more leak
potential but…
V D )
1000
• n e exampe on eleft, if we only set oneorifice valve in the
V D )
D E P T H ( F
T
2000
,
would need on surface aCHP of 1000 psig(dashed thick line) to D
E P T H ( F
T
2000
2500
3000
unoa e we .
• With the unloading
valves, a CHP of 600
2500
3000
GLVOpeningressures
3500 S I B H P
line)
• CAPEX savings on
Slide 4Section 4 – Continuous Flow Design
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Gas Lift
Well Unloadin Process
• Kicking off the well is an operation where lift gas is injected at the
reach the deepest operating gas lift valve where the constant operating gas
injection rate is maintained.. ,
to close sequentially.
• Once kicked off, the shallower gas lift valves to remain closed and gasn ec e a e eepes opera ng va ve on y.
“Any platform shutdown or closing in of wells, the whole process to berepeated.”
• For the Production Pressure Operated valve (PPO) the above process isdone automatically as long as the maximum gaslift pressure is available.
• For the In ection Pressure O erated Valve IPO the aslift ressure had to be reduced (or it does by itself) to close the shallower valves and need to operate at lower operating system press to keep the shallower valvesclosed.
Slide 5Section 4 – Continuous Flow Design
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Gas Lift
No Gas Inject ion - Well Dead
PRESSURE (PSI)
INJECTION GAS
Dummy
Fluid Level
500
0
CASING
PRESSURE
Dummy
Initial Open up, )
1000
Valve 1
Valve 2
D E P T H
( F T T
V D
1500
2000
Valve 3
Orifice 2500
3000
3500 H P
Slide 6Section 4 – Continuous Flow Design
S I
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Gas Lift
PRODUCED FLUID Gas injected at Valve 1
PRESSURE (PSI)
INJECTION GAS
Dummy 500
0
CASING
PRESSURE
Dummy
)
1000
Valve 1
Valve 2
D E P T H
( F T T V 1500
2000
at Valve 1
Valve 3
Orifice 2500
3000
3500 H P
Slide 7Section 4 – Continuous Flow Design
S I
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Gas Lift
IPO Valve Unloadin
PRODUCED FLUID Gas entering V2 & V 1 closing
PRESSURE (PSI)500 10000
500
0
CASING
PRESSURE
Dummy
D )
1000
Valve 1 still o en
Dummy
D E P T H
( F T
T V 1500
2000
a ve
Valve 2
Gas started entering
valve 2
CHP started
2500
Orifice
decreasing
3000
3500
I B H P
Slide 8Section 4 – Continuous Flow Design
S
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Gas Lift
PRODUCED FLUID Gas injected at V2, V1 closed
PRESSURE (PSI)
INJECTION GAS
500
0
CASING
PRESSURE
Dummy
)
1000
CHP decreased till
Dummy
D E P T H
( F T
T V 1500
2000
valve 1 closedValve 1
Valve 2Valve 2 passing gas
2500
Valve 3
Orifice
as starte enter ng
valve 3
3000
3500 H P
Slide 9Section 4 – Continuous Flow Design
S I
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Gas Lift
IPO Valve Unloadin
PRODUCED FLUID Gas injected at V3, V1 V2 closed
PRESSURE (PSI)500 10000
Dummy 500
0
CASING
PRESSURE
Dummy
D )
1000
Valve 1 closed
a ve
Valve 2
D E P T H
( F T T
2000
Valve 3 assin as
CHP decreased
further till valve
2 closed
Orifice 2500
Gas started
entering the
orifice valve
3500
I B H P
Slide 10Section 4 – Continuous Flow Design
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Gas Lift
IPO Valve Unloadin
PRODUCED FLUID Gas injected at Orifice, V1 V2 V3
closed PRESSURE (PSI)500 10000
Dummy 500
0
CASING
PRESSURE
Dummy
D )
1000
Valve 1 Closeda ve
Valve 2
D E P T H
( F T T
2000 CHP decreased
Valve 2 closed
a ve
Orifice 2500
closed
Lift gas3000
3500
orifice
I B H P
Slide 11Section 4 – Continuous Flow Design
S
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Gas Lift
Initial Open Up Without Gas InjectionNo gas injection Well Dead
INJECTION GAS
Fluid Level
PRESSURE (PSI)
0500 10000
CASING
PRESSURE
ummy
Dummy
Initial Open up, Well1000
Valve 1
Valve 2
no ow ng
P T H
( F T T V D )
1500
Valve 3
Orifice
D E
2500
3000
P
Slide 12Section 4 – Continuous Flow Design
S
I B
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Gas Lift
PPO G/L Valve
Lift Gas Injected at Valve 1 (Unloading)PRODUCED FLUID Gas injected at Valve 1
INJECTION GAS
Dumm
500
0500 10000
CASING
PRESSURE
Dummy 1000
Valve 1
Valve 2
E P T H
( F T T V D )
1500
2000
Gas Injected
at Valve 1
Valve 3
Orifice 2500
3000
3500 H P
Slide 13Section 4 – Continuous Flow Design
S I B
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Gas Lift
Lift Gas Start Entering Valve 2
PRODUCED FLUID Gas entering V2 & V 1 closing
INJECTION GAS
PRESSURE (PSI)
0500 10000
CASING
PRESSURE
1000
ummy
Dummy
P T H
( F T T V
D )
1500 Valve 1 startsclosing
Valve 1
Valve 2
D
2500
Valve 3
Orifice
entering valve 2
3000
P
Slide 14Section 4 – Continuous Flow Design
S I B
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Gas Lift
PPO G/L Valve
Gas injected at Valve 2PRODUCED FLUID Gas injected at V2, V1 closed
INJECTION GAS
500
0500 10000
CASING
PRESSURE
Dummy
1000Dummy
E P T H
( F T T
V D )
1500
2000
Valve 1
ClosedValve 1
Valve 2Valve 2
2500
Valve 3
Orifice
3000
3500 H P
Slide 15Section 4 – Continuous Flow Design
S I B
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Gas Lift
Gas started entering at Valve 3PRODUCED FLUID Gas injected at V3, V2 closing
INJECTION GAS
PRESSURE (PSI)
0500 10000
CASING
PRESSURE
ummy
Dummy 1000
Valve 1
Valve 2 P T H
( F T T V
D )
1500Valve 1
Closed
Valve 2
Valve 3
Orifice
D
2500
Gas started
entering Valve 3
closing
3000
P
Slide 16Section 4 – Continuous Flow Design
S I B
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Gas Lift
Gas injected at Valve 3 (unloading)PRODUCED FLUID Gas injected at V3, V1 V2 closed
INJECTION GAS
PRESSURE (PSI)
0500 10000
CASING
PRESSURE
ummy
Dummy 1000
Valve 1
Valve 2 P T H
( F T T V
D )
1500Valve 1
Closed
Valve 2 closed
Valve 3
Orifice
D
2500
Gas entering
Valve 3
3000
P
Slide 17Section 4 – Continuous Flow Design
S I B
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Gas Lift
Lift Gas starts entering at the last mandrelPRODUCED FLUID Gas entering orif ice, V3 closing
INJECTION GAS
PRESSURE (PSI)
500
0500 10000
CASING
PRESSURE
Dummy 1000
Valve 1
Valve 2
E P T H
( F T T V
D )
1500
2000
Valve 1
Closed
Valve 2 closed
Valve 3
Orifice
D
2500
Valve 3 starts closing
entering at
the orifice3000
3500 P
Slide 18Section 4 – Continuous Flow Design
S I B
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Gas Lift
PPO G/L Valve
Lifting at the Deepest MandrelPRODUCED FLUID Gas injected at Orifice, V1 V2 V3
closedINJECTION GAS
Dumm
500
0500 10000
CASING
PRESSURE
Dummy 1000
Valve 1
Valve 2
E P T H
( F T T
V D )
1500
2000
Valve 1
Closed
Valve 2 closed
Valve 3
Orifice 2500
Valve 3 closed
Lift as
3000
3500
injected at
orifice
H P
Slide 19Section 4 – Continuous Flow Design
S I B
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Gas Lift
PRESSURE (PSI)0
0
Available CasingPressure (Kick-off)
T V D )
20 psig drop for transferring
injection down by one valve
IPO -1 D E P T H
( F T
Valve Closing Press
Press
IPO-3
IPO-2
Orifice
Slide 20Section 4 – Continuous Flow Design
S
I B H
F
B H P
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Gas Lift
PRESSURE (PSI)
0500 10000
•When gas is injected through the 1st
500
valve the fluid gradient will become
lighter more and more until the point
that the valve is about to close and the
lifting depth is transferred to the next To avoid the
PPO -1
T T V D )
1000
1500
deeper mandrel. This point is called “
transfer pressure(Pt)” .
•The Pt is used for calculating of valve
re-open ng o
the valve
PPO-3
PPO-2
D E P T
H
( F
2000
opening pressure
•The margin between the final flowing
pressure and Pt is required to avoid the
ps g
2500
3000
re-open ng o e va ve – rans er
Margin
•The differential pressure between
3500
S I B H P
cas ng an e un oa ng gra en s
required to compensate the pressure
drop across the valve
Slide 21Section 4 – Continuous Flow Design
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Gas Lift
PPO Transfer Pressure
Gas
in
Gas
in
Pressure
D e p t h
Transfer
Pressure
Top Valve
Q g a s
Flow Response
Characteristics
Bottom Valve
Slide 22Section 4 – Continuous Flow DesignB A
Pressure
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Gas Lift
Definitions
• Gas Lif t Line/S stem Pressure
PRESSURE (PSI)
0
500 10000Kick-off Pressure (Pko)
• Kick-off Pressure (Pko)
Pko = Psystem – safety factor
This can be used for unloadin a well
500
V D )
• Surface Operating Pressure (Pso)
Pressure that can be maintained at the
well-site to operate the gas lif t valve.
1000
1500
Static liq.
level
D E P T H
( F T so = ko – sa e y ac or
Normally a GL’ed well operates with aCHP = Pso or less.
•
2000
Pdiff
It is the difference between operating
gas inj. press. at depth (Pc) and
established flowing tubing pressure at
2500 Point of Gas Inj
• Point of Balance
3500
Point of Balance
Pr Pwf
Slide 23Section 4 – Continuous Flow Design
Perforation
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Gas Lift
PRESSURE (PSI)500 1000
Kick-off Pressure (Pko)
0
1000
Static liq. level
T V D )
1500
D E P T H
( F
2000
Pdiff
2500Point of Gas Inj
3000Point of Balance
Slide 24Section 4 – Continuous Flow Design
3500
Mid Perforations Pwf Pr
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Gas Lift
Point of Gas In ection for Continuous Flow
CLASS EXERCISE #2
• Tubing ID = 3” , 100% Oil (35° API)
PRESSURE (PSI)
0
1100 21000
Kick-off Pressure (Pko)
• Depth = 8000’, Desired Qo= 4000 b/d
• Desired THP= 100 psig, Rs= 200 scf/bbl
• Pr (at 8000’) = 2900 psig
T T V D )
• Gas Gravity = 0.65
• Pso = 1200 psig
• PI = 5 bbl/psi/d
D E P T H
( • Bottom hole Temp = 160 F
• Flowing THT = 120 F
• Assume Pdiff = 100 psiPdiff
Gas Compress. Factor, z = 0.88
Kill fluid gradient = 0.5 psi/ftPoint of Gas Inj
Calculate
• Point of gas injection
• Gas VolmeMid
Point of Balance
Pr Pwf
Slide 25Section 4 – Continuous Flow Design
• or zePerforation
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Gas Lift
Calculation Ste s
• Plot depth scale on vertical
• Plot ressure scale on horizontal
CLASS EXERCISE #2
• Tubing ID = 3” , 100% Oil (35° API)
• Plot Pr
• From PI calculate press. drawdown req.
• Calculate Pwf
• Depth = 8000’, Desired Qo= 4000 b/d
• Desired THP= 100 psig, Rs= 200 scf/bbl
• Pr (at 8000’) = 2900 psig
• Draw the static gradient line from SBHP
(Kill Fluid Grad.)
• From Pwf draw a gradient line for Oil
• Gas Gravity = 0.65
• Pso = 1200 psig
• PI = 5 bbl/d/psi
s=
• Mark Pso
• Draw casing pressure line from Pso
down to flowin radient line
• o om o e emp =
• Flowing THT = 120 F
• Assume Pdiff = 100 psi
• Mark point of balance / pt. of GI
• Plot FTHP at 0 depth
• Find GLR to connect FTHP with to the
. , .
Kill fluid gradient = 0.5 psi/ft
point of gas injection
• Find Qg necessary for lifting
• Find correct orif ice size
• Point of gas injection
• Gas Volme
•
Slide 26Section 4 – Continuous Flow Design
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Gas Lift
Slide 27Section 4 – Continuous Flow Design
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Gas Lift
Procedure for Using the Vertical Flowing Pressure
Gradient CurvesProcedure:
1. Select the radient curve corres ondin to the iven condition
2. Enter at the known flowing tubing head pressure(FTHP)
3. Draw a vertical to intersect the given GLR line
4. Draw a horizontal line from this point to intersect the depth axis
5. Use this point as the star ing point.
7. Draw the horizontal l ine to intersect the given GLR line
8. Draw the vertical line up to the pressure scale. The intersection point is the pressure at
the required depth
Example:
Tubing ID = 2.5 inchesGross Production = 1000 BPD
Water-Cut = 50 %
API = 35’
GLR = 300 scf/bbl
FTHP = 290 psig
Tubing Depth = 7000 feet
.
2. Draw a horizontal from this intersection point to intersect the depth axis, in this case
2230 ft
3. Since the starting point is 2230 ft, 2230 + 7000 = 9230 ft
4. Draw a horizontal line at 9230 ft to intersect the 300 GLR line
Slide 28Section 4 – Continuous Flow Design
5. Draw a vertical line up to the pressure scale. The flowing pressure for these given
condition at 7000 ft is 2200 psig