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Abstract

This paper presents the results of a study that compares the theoretically calculated power consumption of a Hydraulic Gas Pump, rod pumps, and electric submersible pumps. The results indicate that, depending on the flowing bottomhole pressure of a well, a Hydraulic Gas Pump can have lower power costs than a rod pump or a submersible pump.

We present a method for calculating the power cost of a Hydraulic Gas Pump and discuss the relationship of the power cost of this pump to the flowing bottomhole pressure. Several graphs compare the calculated power consumption of a rod pump, submersible pump, and Hydraulic Gas Pump for well depths ranging between 6,000 and 10,000 feet; flowing bottomhole pressure ranging between 500 and 2,000 psi; and production rates of 300 and 500 BLPD.

Introduction

The Hydraulic Gas Pump is a proposed pump for oil and gas wells. Its concepts were first presented in Ref. 1. When a new or improved artificial lift system is proposed, we must demonstrate that the system can be an economic lift method. We must outline the producing environments in which the new system is more economic than the existing artificial lift systems.

When we compare the economics of different artificial lift systems, we analyze economic measures such as capital costs, power costs and maintenance costs. Often other factors such as depth, lift capacity, produced fluid characteristics, availability of lift gas, geographic location or wellbore condition affect the economics or practicality of different lift systems. Therefore the economic comparison of artificial lift systems should be evaluated for specific installations and producing environments.

The specific application of the Hydraulic Gas Pump is for gassy, deep, viscous, or high temperature environments. The objective of this paper is to present a method for calculating the power cost of the proposed pump and discuss its applications.

Operation Method of the Hydraulic Gas Pump

Fig. 1 shows the operation of the Hydraulic Gas Pump. This pump works by gas pressure. It alternately injects a volume of pressurized gas through an injection line into a subsurface pump chamber to displace liquids to the surface, then it vents the chamber to allow it to refill.

The compression system of the Pump is a rotative system. It includes a high pressure compressor and a pressure vessel. A well on a Hydraulic Gas Pump produces gas through its casing annulus, and when the system vents its chamber, the pressurized gas is vented into the casing annulus also. The compressor pressurizes the produced and vent gas from the casing and provides power gas to the pump.

The compression system is similar to the compression systems that have been developed for Compressed Natural Gas (CNG) for fueling vehicles.

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