A New Gas Lift System

Abstract

Abstract A system for intermittent or continuous gas lift which uses rubber balls as pistons to prevent wasteful gas slippage is described. Two parallel strings of tubing are used. The rubber balls are forced down one string and the production is lifted up the other. The rubberballs are separated from the oil and gas at the surface and reinjected with the lift gas by a special mechanism at the surface. Field tests indicate that the pump offers an economical solution for pumping wells where low production, foamy crude, high gas-oil ratio, deep production, or corrosion is a problem. One unique nature of the pump is that adjustments and repairs can be made at the surface by one or two men without the use of heavy equipment. Introduction Finding a method to economically produce low fluid level, low production wells is becoming a more urgent problem each year. High lifting costs for wells of this type produced by generally used methods results from these causes: frequent pulling jobs due to rod failures, tubing wear, pump replacement; paraffin troubles; corrosion; low efficiency in handling gassy or foamy crudes; and improperly adjusted equipment. Hydraulic subsurface pumping units and intermittent gas lift alleviate some of these problems, but they are not universally useable because of limitations peculiar to each. In an effort to find a lift system solving as many of the problems of pumping as possible, the Stanolind Research Department made an investigation of several possible methods of lift. One method developed has been called the "ball pump", and will be described here. The increasing availability of natural gas in oil fields, either from gas wells, or from gas compression plants used for secondary recovery projects, existing rotative gas lift systems, gasoline plants, or transmission facilities, indicated that new development should be directed toward using gas as the lifting medium. By eliminating all reciprocating parts in the hole, gas lift removes the cause of many troubles of conventional pumping. However, existing intermittent gas lift systems have certain weaknesses which need improvement. For instance, though recent development of wire-line removable gas lift valves have lessened the need for pulling tubing for repairs or adjustments, low gas lift efficiency is still a problem. The efficiency is affected by the depth of the lift, the kind of fluid lifted, and the spread between the opening and closing pressures of the working gas lift valve. Paraffin control is also a serious problem.