Lecture12a_Basic Gaslift Sec 4 - Unloading

7/28/2019 Lecture12a_Basic Gaslift Sec 4 - Unloading

http://slidepdf.com/reader/full/lecture12abasic-gaslift-sec-4-unloading 1/28

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



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


S I B

F B



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




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




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.




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


S I



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


S I



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


S



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


S I



Gas Lift

IPO Valve Unloadin

PRODUCED FLUID Gas injected at V3, V1 V2 closed


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




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


S



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


S

I B



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


S I B



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


S I B



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


S I B



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


S I B



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


S I B



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


S I B



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


S I B



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


S

I B H

F

B H P



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




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



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


Perforation



Gas Lift


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


3500

Mid Perforations Pwf Pr



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


• or zePerforation



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

•




Gas Lift




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


5. Draw a vertical line up to the pressure scale. The flowing pressure for these given

condition at 7000 ft is 2200 psig

Date post:	03-Apr-2018
Category:	Documents
Upload:	reborn2
View:	226 times
Download:	3 times

Lecture12a_Basic Gaslift Sec 4 - Unloading

Documents