Overview of Artificial Lift Systems

Abstract

Summary This paper gives guidelines to assist in the selection of artificial lift methods. The most important guideline is determination of the flow rates possible by each method. This requires preparation of pressure/flow rate diagrams combining well-inflow performance relationships with tubing intake curves. The tubing intake curve includes, pressure loss in the complete piping system and/or pressure loss in the complete piping system and/or pressure gains by the pumping method. Many other pressure gains by the pumping method. Many other factors other than rate, such as location, retrievability by wireline, corrosion, paraffin, scale deposition, cost, operating life, and others, influence the final selection of lift equipment. Introduction This paper provides an overview of artificial lift systems and gives guidelines indicating when one system is better to use than another. Advantages and disadvantages are given with examples in the selection of lift methods. This list represents the relative standing of lift systems based on the number of installations throughout the world:sucker rod pumping (beam pumping)gas liftelectric submersible pumping,hydraulic piston pumping,hydraulic jet pumping,plunger piston pumping,hydraulic jet pumping,plunger (free-piston) lift, andother methods. This differs according to field, state, and country. New lift systems are being developed and tested continually. The lifting of heavy viscous crude oils requires special attention, and methods designed specifically for this purpose are being tested. Wells located offshore and in deep water present specific problems, and surface- space limitations become important. The artificial lift method should be considered before the well is drilled. Obviously this cannot be done on wildcat wells. but it must be done on all subsequent development wells. The drilling program must be set out to ensure hole sizes that permit adequate casing and tubing sizes. permit adequate casing and tubing sizes. One serious limitation to artificial lift installations has been the installation of small casing sizes, which limits the installation to specific tubing sizes to obtain the objective flow rate and, in particular, limits the size of retrievable gas lift equipment and/or pumping equipment. The installation of gas-lift mandrels that accept only 1 -in. (2.5-cm) OD gas-lift valves is common in the U.S.. and serious limitations on gas passage volumes are imposed on the system with this small valve. Also, the better performance characteristics of the 1 1/2-in. (3.8 1 -cm) OD valve are lost. For the pumping systems. the smaller capacity pumps must be used in the smaller casing sizes, and sometimes the advantage of retrievable pumps is lost. pumps is lost. Surface-space limitations become an important factor. For example, if large compressors for gas lift or large generators for electrical pumping are anticipated for offshore platforms, provisions must be made in the original design to allow for both weight and space on the platforms. Some engineers are invariably optimistic about platforms. Some engineers are invariably optimistic about natural flow in the planning stage, and in many instances they still maintain that artificial lift will not be required during the life of a field. This leads to very poor planning, especially on offshore facilities. planning, especially on offshore facilities. In the design of artificial lift systems for a well, it is recommended that it initially be treated as if it were a flowing well--i.e., a production systems graph should be prepared to see if the well is capable of flowing and, if it is, at what rate. The artificial lift analysis can be placed on the same plot. Numerous flowing wells will show increased flow rates when placed on artificial lift. The purpose of any artificial lift system is to create a predetermined tubing intake pressure such that the predetermined tubing intake pressure such that the reservoir may respond and produce the objective flow rate. The design and analysis of any lifting system can be divided into two main components. The first is the reservoir component (inflow performance relationship), which represents the well's ability to produce fluids. JPT P. 2384