ASME/API GAS LIFT WORKSHOP DOWNHOLE GAS LIFT AND THE FACILITY John Martinez Production Associates...

ASME/API GAS LIFT WORKSHOP

DOWNHOLE GAS LIFT AND THE FACILITY

John Martinez

Production Associates



DOWNHOLE GAS LIFT AND THE FACILITY

• SYSTEM COMPONENTS• SYSTEM BACKPRESSURE – NUMBER OF

WELLS – OPERATING FACTOR• POWER INPUT AND SYSTEM

BACKPRESSURE• COMPRESSION OPTIONS• DEHYDRATION OPTIONS• MEASUREMENT, CONTROL, REMOTE

TRANSMISSION• FLOW RATE STABILITY & GAS INJECTION

RATE


WHY IS GAS LIFT IMPORTANT?

COURTESY EXXONMOBIL – MIKE JOHNSON


WHY IS GAS LIFT IMPORTANT?

COURTESY SHELL – JIM HALL


FACILITY EQUIPMENT DRIVES GAS LIFT AND IS

THE LARGEST CAPITAL EXPENDITURE

• Onshore operator wanted more rig work and less wireline work

• Standby compressor added due to the remote location


FACILITY EQUIPMENT DRIVES GAS LIFT AND IS

THE LARGEST CAPITAL EXPENDITURE

• Offshore operator depends totally on wireline work

• Excellent dehydration was required because gas had CO2


SYSTEM BACKPRESSURE NUMBER OF WELLS OPERATING FACTOR

• RATE PER WELL VARIES WITH SEPARATOR PRESSURE (SYSTEM BACKPRESSURE)– EXPLORATION TEST RATES AND PVT DATA

• SIMULATE RESERVOIR BEHAVIOR• SIMULATE WELL DELIVERY

• APPLY AN OPERATING FACTOR• SIMULATE WELLS NEEDED BASED ON

BOTH RESERVIOR AND DELIVERY PERFORMANCE



RESERVOIR PRESSURE,

Psig

& Water, %

TARGET

FIELD OIL RATE

stb/d

OPERATING

FACTOR

DAILY

OIL

REQUIRED

stb/d

2400 @ 0% 100,000 0.93 107,530

2000 @ 25% 90,000 0.86 104,650

1600 @ 50% 50,000 0.83 60,240



RESERVOIR

PRESSURE

Psig

& Water %

OIL RATE PER WELL

stb/d

@200 psig INLET

WELL

COUNT

@200 psig INLET

OIL RATE PER WELL

stb/d

@50 psig INLET

WELL

COUNT

@50 psig INLET

2400 @ 0% 2000 54 2200 49

2000 @ 25% 1050 100 1180 89

1600 @ 50% 200 302 450 134


COMPRESSOR SUCTION AND DISCHARGE PRESSURE EFFECTS

Discharge Pressure vs. Gas Lift Gas Requirement

0 500 1000 1500 2000

INJECTION GAS LIQUID RATIO, SCF/STB

0

500

1000

1500

2000

2500

3000

3500

PR

OD

UC

TIO

N R

AT

E,

GR

OS

S S

TB

/D

PI=10, INJ @ 7000',INJ PR = 1100 PSIGPI=10, INJ @ 6000',INJ PR = 800 PSIGPI=10, INJ @ 5000',INJ PR = 550 PSIGPI=1, INJ @ 7000',INJ PR = 900 PSIGPI=1, INJ @ 6000',INJ PR = 700 PSIGPI=1, INJ @ 5000',INJ PR = 500 PSIG

PRODUCTION VS INJ. GAS & INJ. PRESS.WELL 1 & 2: INJ. PRESS. VARIES WITH INJ. DEPTH, P SEP = 50 PSIG



Suction Pressure vs. Gas Lift Gas Requirement

0 500 1000 1500 2000


1000

1500

2000

2500

3000

3500P

RO

DU

CT

ION

RA

TE

, G

RO

SS

ST

BB

L/D

P SEP = 20 PSIGP SEP = 50 PSIGP SEP = 100 PSIGP SEP = 150 PSIG

PRODUCTION VS INJ. GAS & SEP. PRESS.WELL 1: PI = 10 TBG = 4 1/2" FL = 3.958" & 2000 FT LONG INJ. @ 7000 FT

0 500 1000 1500 2000


200

300

400

500

600

700

PR

OD

UC

TIO

N R

AT

E,

GR

OS

S S

T B

BL

/D

P SEP = 20 PSIGP SEP = 50 PSIGP SEP = 100 PSIGP SEP = 150 PSIG

PRODUCTION VS INJ. GAS & SEP. PRESS.WELL 2: PI = 1 TBG = 2 7/8" FL = 2.9" & 2000 FT LONG INJ. @ 7000 FT



Optimize Compression Horsepower (BHP)

0 50 100 150 200

SEPARATOR PRESSURE, PSIG

0.06

0.07

0.08

0.09

0.1

0.11

0.12

0.13

0.14

BR

AK

E H

P P

ER

ST

B

WELL 1WELL 2

COMP. BHP/STB VS SEP. PRESS.WELL 1: PI = 10, RATE = 3000 STB/D, INJ P = 1100 PSIG

WELL 2: PI = 1, RATE = 500 STB/D, INJ P = 900 PSIG


COMPRESSION OPTIONSOPERATING EFFECTS

• WATER VAPOR IN THE GAS– REQUIRES MORE POWER FOR COMPRESSION

COMPARED TO SIMULATING DRY GAS– HEAT DUTY FOR COOLERS GOES UP –

EXCHANGER SIZE BASED ON DRY GAS IS TOO SMALL

• TEMPERATURE OF GAS AND AMBIENT– AVERAGE USED IN DESIGN, ACTUAL

OPERATING CAN BE SIGNIFICANTLY HIGHER– DRIVER DERATES, CANNOT SUPPY SUFFICIENT

POWER– COMPRESSOR CYLINDER (RECIP) OR IMPELLER

WHEELS (CENTRIFUGAL) CANNOT MOVE THE DESIGN RATE


COMPRESSION OPTIONS - RECIPROCATING

• Reciprocating compression applied to smaller rates

• Good discharge pressure flexibility, limit on cylinder capacity

• Matched with gas engine or electric motor

Dresser Industries


COMPRESSION OPTIONS - CENTRIFUGAL

• Centrifugal compression applied to large rates offshore or internationally

• Large gas throughput in a small package

• Sensitive to gas composition changes

• Mated with gas turbine or electric motor

Solar Gas Turbine Dresser-Clark


DEHYDRATION OPTIONS

Triethylene glycol (TEG) is the common absorption dehydration method

Mole sieves adsorb water vapor onto the surface in the bead


DEHYDRATION OPTIONS

WATER CONTENT BASED ON PRESSURE AND TEMPERATURE IS PREDICTABLE

GPSA


DEHYDRATION OPTIONS

HYRATE CONDITIONS ARE PREDICTABLE

GPSA


MEASUREMENT, CONTROL, REMOTE TRANSMISSION

• MEASURE INJECTION GAS LIFT GAS– SINGLE PHASE FLOW– STEADY PRESSURE (SHOULD BE)– MOST RELIABLE (COMPARED TO PRODUCTION

SEPARATOR)

• USE LOW POWER ACTUATED CHOKES USING SOLAR PANELS

• RADIO TRANSMISSION OF GAS MEASUREMENT DATA, WELLHEAD AND CASING PRESSURE AND TEMPERATURE


MEASUREMENT, CONTROL, REMOTE TRANSMISSION

• INSTALL DOWNHOLE PRESSURE SENSORS IN NEW WELLS– MONITOR FLOWING BOTTOMHOLE PRESSURE– ADJUST GAS LIFT GAS RATE TO KEEP

MAINTAIN THE FLOWING BHP (NOT CONTINUOUSLY)

– MONITOR SUDDEN INCREASES WHICH INDICATE VALVE PROBLEM OR SHIFT IN POINT OF LEFT

• TRANSMIT DATA TO OPERATIONS CENTER, PLATFORM OR EVEN HOUSTON, FOR ANALYSIS AND ADJUSTMENT


FLOW STABILITY AND GAS INJECTION RATE

• VALIDATED SIMULATION AND PRODUCION TESTS CAN DETECT UNDER PERFORMING WELLS DUE TO LIFT POINT SHIFT

• COMPRESSOR OUTAGE AND FREEZING

• SIMULATE VELOCITY AND FLOW PATTERN


FLOW STABILITY AND INJECTION RATEGAS RATE PERMITTING SLUG FLOW, VELOCITY

LESS THAN 5 FT/SEC


FLOW STABILITY AND INJECTION RATEGAS RATE PROMOTES STABLE ANNULAR FLOW,

VELOCITY GREATER THAN 5 FT/SEC


FLOW STABILITY AND INJECTION RATEGAS RATE PERMITS SLUG/CHURN FLOW,

VELOCITY ABOUT 5 FT/SEC


GAS LIFT OPTIMIZATION DEPENDENT ON WELL PERFORMANCE AND

FACILITY AVAILABILITY

• COMPRESSION AVAILABLE >99%• EFFECTIVE DEHYDRATION

– FREEZING IS A COMMON FIELD PROBLEM– 7 LB/MM (3 LB/MM IN COLD CLIMATES)

• GAS SYSTEM DESIGN – LOW SUCTION PRESSURE– HIGH DISCHARGE PRESSURE– POWER REQUIRED PER BARREL IS LESS AT

LOW SUCTION PRESSURE


GAS LIFT OPTIMIZATION DEPENDENT ON WELL PERFORMANCE AND

FACILITY AVAILABILITY• FIELD SIMULATION FOR DEVELOPMENT

– RESERVOIR PRESSURE DECLINE AND WATER INCREASE– RATE VS INJECTION GAS DELIVERABILITY AT EACH

RESERVOIR CONDITION– WELL COUNT FOR DIFFERENT OPERATING CONDITIONS

• GAS MEASUREMENT– MAKE THE INJECTION GAS METER RELIABLE– MATE WITH LOW POWER CHOKE ACTUATOR AND REMOTE

TRANSMISSION CAPABILITY• FLOW STABILITY

– SIMULATE FLOW PATTERNS AND MATCH TO MEASURED AND OBSERVED BEHAVIOR

– ANNULAR FLOW– VELOCITY > 5 FT/SEC

ASME/API GAS LIFT WORKSHOP DOWNHOLE GAS LIFT AND THE FACILITY John Martinez Production Associates...

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