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Gas Lift Systems

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Objectives

Identify the major components of a Gas

Lift System

Identify Gas Lift applications and

limitations

Have a basic understanding GL Systemoperating principles.

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Gas Lift

Gas lift is the second most commonly

used form of artificial lift today.

Its usage is very common offshore

because of space limitations and

subsurface safety valve requirements.

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Gas Lift

Gas injected at depth in order to lighten the

density of the liquid column

Decreases hydrostatic pressure

Injection is performed in stages from top to

bottom via gas lift valves until all liquid isremoved and well is flowing

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Gas Lift

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Gas Lift

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Gas Lift

An extension of natural flow

Simply a constant controlled injection of

high pressure gas into the tubing

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Injected

gas

Injected

gas

Continuous gas lift Intermittent gas lift

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Advantages

Takes full advantage of the gasenergy available in the reservoir

A high production volume method

Can handle sand or trash

Valves can be changed by wireline

Works with SSSV

Minimal downhole mechanical

devices

Full tubing bore capabilities

Excellent in deviated wellbores

Disadvantages

Can not pump off the well

Minimum bottom hole

production pressure increases

both with depth and volume

Source of gas supply

Gas distribution system

May require a compressor

Must treat corrosive gasses

(must be a dry gas)

Gas Lift

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Gas Lift Valves

Tubing

Tubing entryport

Valve entryports

Stem & seat

Gas chargeddome

Bellows

Ap

Pt

Pc

Ab

Pd

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Valve with spring Valve with bellows only

C

Pd

Ab

Pc

Av

Pd

Ab

D

Pc

Av

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Tubing

pressure

Latch

Packing

Casing

pressure

Packing

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1

Positioningsleeve

Locator key

Pivot lever

arm

Latch

2 3

200 lbs.

AA

A - A

4 5

0 0 0

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04

00

800

1200

1600

2000

0

1000

2000

3000

4000

5000

6000

Depth, ft

Pwf

Optimum point of injection

Casing pressure gradient

Pr

psi

Perforation

depth

Flowing gradient above point ofinjection

Static reservoir gradient

0 0 0

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04

00

800

1200

1600

2000

0

1000

2000

3000

4000

5000

6000

Depth, ft

Pwf

Optimum point of injection

Casing pressure gradient

Pr

psi

Perforation

depth

Flowing gradient above point of injection

Kick off point

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0

2000

4000

6000

8000

10000

0 400 800 1200 1600 2000 2400

Pressure

Dep

th

2530'

4000'

5100'

6000'

6600'7100'7500'

600bpd

7800'8050'8250'

Equilibrium Curve

Pwh (min)

Pinj

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Lower zone perforations

Single packer

Upper zone perforations

Dual packer

Gas lift valve and mandrels to be staggered

Injection gas

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Gas Lift

Surface equipment

Gas supply source:

gaswell

separator gas with compressor

Surface gas flow distribution & control

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Key words Lighten fluid column

extension of natural flow static gradient

flowing gradient

drawdown casing pressure gradient

optimum point of injection

kick off point

gaslift valves, wireline change out

gaslift gas source

gaslift gas distribution

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End of Session