Diseño Y Tecnología De Gas Lift

Schlumberger
Gas Lift Design and Technology

Schlumberger
Well Completions and Productivity
Chevron Main Pass 313 Optimization Project
09/12/00

GAS LIFT DESIGN AND TECHNOLOGY

1.

Introduction & Basic Principles of Gas Lift

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Gas Lift Design And Technology
Schlumberger1999

1. Introduction & Basic Principles of Gas Lift

CHAPTER OBJECTIVE: To give an overview of gaslift principles and their applications
with illustrations of continuous and intermittent gas lift installations.

Most wells completed in oil producing sands will flow naturally for some period of time after they begin
producing. Reservoir pressure and formation gas provide enough energy to bring fluid to the surface in a
flowing well. As the well produces this energy is consumed, and at somepoint there is no longer enough
energy available to bring the fluid to the surface and the well will cease to flow. When the reservoir
energy is too low for the well to flow, or the production rate desired is greater than the reservoir energy
can deliver, it becomes necessary to put the well on some form of artificial lift to provide the energy to
bring the fluid to the surface. The types ofartificial lift available are illustrated in Figure 1-1. When gas
lift is used, high-pressure gas provides the energy to enable the well to produce.

FIGURE 1-1: Artificial Lift Systems

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Gas Lift Design And Technology
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When a well is completed, a series of conductor pipes and accessories are installed during well
completion operations. The basic components of thesystem are labeled in Figure 1.2. This is a simplified
illustration of a cased hole single zone completion. Dual and triple completions are much more complex
and will not be considered here. The inner surface of the well bore is supported by the casing string.
There may be up to three separate casing strings including a surface and intermediate string. The space
between the tubing and casing iscalled the annulus. The packer seals the annulus just above the
producing zone. The casing has been perforated adjacent to the producing zone to allow entrance of gas
and liquid products into the wellbore or the tubing string may extend into the open hole. When reservoir
drive does not provide enough pressure to lift fluids to the surface, additional equipment must be
installed to help lift thefluids. There are four basic types of artificial lift: sucker rod pumping, hydraulic
pumping, centrifugal pumping and gas lift.

Figure 1-2 Completed Well

Table 1.1 compares these systems and lists the advantages and disadvantages of each. As you can see
there are two basic types of gas lift used in the oil industry. They are called continuous flow gas lift and
intermittent gas lift. Thetwo types operate on different principles and it is always advisable to treat them
as two separate subjects.

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Gas Lift Design And Technology
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Table 1.1 Types of Artificial Lift Systems
Continuous
Disadvantages

Advantages
GAS LIFTING
1. Takes full advantage of the gas energy
available in the reservoir.
2. Is a high volume method.
3. Equipment can becentralized.
4. Can handle sand or trash best.
5. Valves may be wireline or tubing
retrieved.

1. Cannot pump off and minimum bottom
hole producing pressure in creases both
with depth and volume.
2. Must have a source of gas.

Intermittent
1. Can obtain lower producing pressure than
continuous gas lift obtains and at low
rates.
2. Equipment can be centralized.
3. Valves may be wireline ortubing
retrieved.
Rod Pumping:
1. Is possible to pump off.
2. Is best understood by field personnel.
3. Some pumps can handle sand or trash.
4. Where suitable, it is usually the cheapest
lift method.
Hydraulic Pumping:
1. High volume can be produced from great
depth.
2. It is possible to almost pump off.
3. Equipment can be centralized.
4. Pumps can be changed without pulling
tubing....