fall 2001 asme/api gas lift workshop aberdeen

NUMERICAL MODEL FOR THE PREDICTION OF FLUID PRODUCTION AND GAS CONSUPTION OF GAS CHAMBER PUMPS

PDVSAINTEVEP

Fall 2001 ASME/API Gas Lift WorkshopAberdeen

NUMERICAL MODEL FOR THE PREDICTION OF FLUID NUMERICAL MODEL FOR THE PREDICTION OF FLUID

PRODUCTION AND GAS CONSUMPTION OF GAS CHAMBER PUMPSPRODUCTION AND GAS CONSUMPTION OF GAS CHAMBER PUMPS


PDVSAINTEVEP Outline

• Introduction

• Numerical Model

• Field Test Facility

• Field Test Results

• Conclusions


PDVSAINTEVEP IntroductionIntroduction

open

Valve 2.

Valve 1. closed

open



open

Valve 2.

Valve 1. closed

open

open

Valve 2.

Valve 1. closed

open



AdjChoke

Inj. Gas &vent string

AdjChoke

Vent motor valve

Pilot Control System

Inj. gas motor valve

Inj.Gas line

Flowline

Csg

InsertChamber

Perfs

Intake check valve

Discharge check valve

Chamber dip tube

Prod conduit

Crossover



Flow

Supply GasReturn Gas

Exhaust

Standing ValveAssembly

Flow Tube

ROD

Plunger

BarrelSwitchingMechani SM Valve Assembly

UnloadingValve

Choke



Production

Gas lift val.& Mandrel

Vent

Injection

B1-A BE2.75-A

standingValve

BleedOrifice

BSTGCP


PDVSAINTEVEP

Advantages

• Can Handle: gassy & viscous fluids

• High Temperatures (stimulation by cyclic steam

injection)

• Can be run and pulled with wire line equipment

• No fallback losses

• Completions can be very simple

IntroductionIntroduction


PDVSAINTEVEP

Disadvantages

• Higher cost in surface controller equipment than

in Gas Lift

• For complex designs parts are subject to wear

and replacement

• A High-Pressure gas source is required

IntroductionIntroduction


PDVSAINTEVEP

General Calculation Algorithm

1) Input data: reservoir, completion,fluid properties, separation & injection pressure

2) Calc. minimum and maximum liquid level

MINIMUM LEVEL

MAXIMUM LEVEL

80% OF STATIC RESERVOIR PRESSURE

3) Calc. column increments

4) For each column calculates the liquid prod. and gas consumption separately

21 43 ….N

Numerical ModelNumerical Model


PDVSAINTEVEP

Calculation procedure for each column (1,2,3,….n)

•Column accumulation

•Gas Injection

•Fluids displacement by gas expansion without injection

•Gas Venting

•Fluids into the well (Pgas<Pres<Pcas)

•No Reservoir inflow (Pres<Pgas<Pcas)

•No Reservoir inflow & (Pres<Pcas<Pgas) Fluid displacement

•Gas depressurization No Reservoir inflow (Pres<Pcas<Pgas)

Model Stages

Numerical ModelNumerical Model


PDVSAINTEVEP Numerical ModelNumerical Model

Calculation procedure for each column (1,2,3,….n)Liquid Column Accumulation

.@1

Lmin

Pwf tt

dt

dL

Vogelt

dt

dLLL

ttmintt

1

2

ncolumn for 2 maxtt LL

no

LPwfPwf

LL

ttt

ltt

tt

1

2

1

yes

stage-sub inj. gas 1 To st

ncolumn for on accumulati liquid tT




All other Stages

System divided in the following control volumes

• Gas injection tubing

• Liquid chamber+subsurface valve

• annulus space

• flow line




All other StagesInitial conditions: L, Pwf, Pinj, time, gas injected=0, liquid velocity

For each C.V. :Continuity, Momentum, Eq. of state, Gas flow through chokes, liquid flow through chokes

1@

.,,

dt

dP

for seq' algebraic ofset

ttimedt

dVeloc

dt

dL

112

'

Euler

ttt t

Conditions at t2: L, Pwf, Pinj, time, gas injected, liquid velocity...

Stage check

Finish stage


PDVSAINTEVEP

open

Valve 2.

Valve 1. closed

open

Test FacilityTest Facility

2500 ft

Pressure and temp. sensors

3 1/2” tubingR-2823 API


PDVSAINTEVEP Test ProgramTest Program

Average liquid column length = 520 ft

Gas injection and venting stages

M e a s u r e d G a s L i q u i d R a t i o sG a s F l o w

R a t e . ( M C F D )I n j . G L R ( S C F / B r )

4 2 0 1 1 3 5 , 65 9 7 1 2 2 3 , 57 9 6 1 5 4 6 , 08 4 6 1 3 7 1 , 99 2 9 1 1 9 7 , 8

1 0 1 4 1 6 6 9 , 21 1 1 9 2 3 1 4 , 91 1 7 5 1 6 6 1 , 8


PDVSAINTEVEP Test ResultsTest Results

Gas Inj. Rate 420 MSCFD

0

100

200

300

400

500

600

700

800

900

1000

09:28:10 09:31:03 09:33:56 09:36:48 09:39:41 09:42:34 09:45:27 09:48:20

Time (s)

Well

head

pre

ssu

re (

psi)

.

MeasuredCalculated



Pressure drop across the R-28 valve. Gas rate 597 MSCFD

-10

-5

0

5

10

15

02:06:40 02:09:33 02:12:26 02:15:18 02:18:11 02:21:04

Time (s)

Pre

ss

ure

dro

p (

ps

i)

Measured

Calculated



Well head pressure during gas venting stage

0

100

200

300

400

500

600

700

13:52:19 13:53:46 13:55:12 13:56:38

Time (s)

Pre

ssu

re (

psi

)

Measured well headpressure

Calculated well headpressure



E x p e r i m e n t a l R e s u l t sG a s F l o w

R a t e .( M C F D )

I n j .T i m e( m i n )

I n i t i a lC o l u m n

( f t )

F i n a lC o l u m n

( f t )

G a s I n j .p e r C y c l e

( S C F )

S u r f a c e I n j .P r e s s u r e

( p s i )

4 2 0 2 2 , 0 0 7 5 5 1 0 8 6 4 2 8 9 1 3 , 95 9 7 1 4 , 6 6 8 0 6 1 7 3 6 0 8 5 8 9 6 , 97 9 6 1 4 , 0 0 7 7 8 1 6 7 7 7 3 9 9 0 9 , 78 4 6 1 2 , 0 0 9 3 8 2 7 4 7 0 5 0 8 7 8 , 69 2 9 8 , 6 7 8 4 2 3 3 6 5 5 9 3 8 6 1 , 5

1 0 1 4 7 , 6 7 8 4 0 4 1 1 5 3 9 9 8 5 1 , 01 1 1 9 7 , 8 3 7 9 3 4 6 3 6 0 9 1 8 3 6 , 61 1 7 5 7 , 1 6 8 6 5 5 2 8 5 8 5 2 8 2 8 , 4



• Very inefficient completion used for the tests

• Very small liquid columns simulating a low producer well

• Tests with c-t gave less than 50% of these GLRs

M e a s u r e d G a s L i q u i d R a t i o sG a s F l o w

R a t e . ( M C F D )I n j . G L R ( S C F / B r )

4 2 0 1 1 3 5 , 65 9 7 1 2 2 3 , 57 9 6 1 5 4 6 , 08 4 6 1 3 7 1 , 99 2 9 1 1 9 7 , 8

1 0 1 4 1 6 6 9 , 21 1 1 9 2 3 1 4 , 91 1 7 5 1 6 6 1 , 8



M o d e l d e v i a t i o nG a s F l o w R a t e .

( M C F D )G a s I n j . T i m e

D e v i a t i o n( % )

G a s V o l u m e p e rC y c l e D e v i a t i o n

( % )

M a x . S u r f a c e G a sI n j . P r e s s u r e

( % )

4 2 0 1 , 2 1 , 1 0 , 85 9 7 1 , 4 1 , 3 0 , 87 9 6 - 6 , 1 - 6 , 1 - 0 , 88 4 6 - 6 , 2 - 6 , 2 - 1 , 39 2 9 - 2 , 6 - 2 , 6 - 0 , 9

1 0 1 4 - 5 , 4 - 5 , 4 - 2 , 51 1 1 9 - 7 , 4 - 7 , 4 - 2 , 21 1 7 5 - 9 , 1 - 9 , 1 - 3 , 5


PDVSAINTEVEP

• A numerical model was developed for gas chamber pumps

• A field scale test program was carried out on gas pumps.

• Even though the completion used for the tests was highly inefficient, the injection GLR measured for each test were within the economical limit.

• The model predicts the test results within a 10% global accuracy for the operating conditions found during the tests.

ConclusionsConclusions

fall 2001 asme/api gas lift workshop aberdeen

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