A novel gas separator design has been developed and successfully tested in several beam pumped wells which were subject to severe gas interference. This paper presents a detailed description of various designs to cover various ranges of fluid production for the most common sizes of completions (4-1/2 to 7 inch casing) and rates from 120 to 825 barrels of liquid per day.
The new design is based on two innovations:
Decentralization of the gas separator in the casing, insures that a minimum amount of gas enters the separator.
The presence of two ports located on the narrow side of the annulus and placed a significant distance apart allow continuous flow of fluids into and out of the separator during both the upstroke and downstroke of the pump.
These innovations have resulted in a gas separator efficiency much greater than that of conventional designs.
Numerous studies have been performed in recent years in an attempt to improve the performance and efficiency of a beam pumped system. See references 1 through 8. The studies include the motor or power unit, the surface pumping system, the rod string and the downhole pump. In wells which produce gas, the inefficient separation of gas from liquid at the pump inlet often results in very poor pump performance and low overall efficiency of the entire pumping system. This can be verified by obtaining a dynamometer pump card on a well which indicates considerable free gas in the pump even though liquid is present in the casing annulus in the form of a high gaseous liquid column.
The preferred technique for separating gas from the pump is to place the tubing fluid entrance ports (or gas anchor ports) below the bottom of the formation's perforated interval as shown in Figure 1. The natural separation of gas and liquid by gravity will result in relatively gas-free liquid entering the pump intake if the downward liquid velocity in the casing/tubing annulus is less than approximately 6 inches per second.