Gas lift is a good artificial lift for those high gas/oil ratio (GOR) wells. But the positive displacement pump is used on many special conditions such as the limitation of high pressure gas, large equipment investment and low remaining recoverable reserve. To decrease the gas into the pump, the gas would generally be separated at bottom hole, then enter the annulus between the tubing and the casing (tubing-casing annulus), eventually flow in air or enter oil pipeline by many control valves at wellhead. In this system, the gas is a potential damage factor to the pump. So the pump efficiency is low and the frequency of pump checkout is high.
In this paper, a new approach is presented. One or two gas lift valves are installed on the tubing near the wellhead. The other equipments are same as the conventional system. While the casing pressure reaches the aimed value, high pressure gas in the annulus automatically enter the tubing. This lightens the weight of the fluid in the tubing above the working valve, which assists pumping the liquid.
This approach is applied in sucker rod pump system in Wendong oilfield. Dynamometer cards from 2 typical wells indicate that the pump efficiency is improved and the daily fluid production rate is enhanced. Then a similar approach is applied in Electric Submersible Pump system (ESP) and the same good result is obtained. This paper presents the description of this new approach and reports the results obtained in those field trials. The energy-saving theory is analyzed and the design procedure is given.