Improving The Application Of Basic Research Of Gas-lift Pumping System Efficiency

Gas lift is a kind of mechanical oil production used widely and early, which plays a great role in production engineering and next to the sucker-rod pumping in oil production. In China, gas lift is popularized in Zhongyuan, Tuha, Talimu, Sichuan, Nanhai and so on. With western oilfield and offshore oilfield developed, gas lift has huge attractiveness and vitality for gas lift has many strongpoint that gas lift adapt to deep well, high productivity, complex layer and complex exploitation condition. So how to improve the efficiency of gas-lift system is hotspot.Gas lift is a kind of artificial lifts that has much strong systematization. Gas-lift system is comprised of gas-lift pumping plant, gas distribution network, gas-lift well, pipeline between gas-lift well and metering station. And that each one of the last four parts has changed will affect operation of the gas-lift system. The gas-lift pumping plant is the power source, the gas volume has a direct effect on the scale of gas lift and the selection of power motor will directly affect the cost of gas-lift system. The gas distribution network handed down the gas energy, the pressure and the temperature of the end have an direct effect on the technology design of gas-lift well, as a result, the operation of gas-lift well is affected. Gas-lift well is the heart of gas-lift system and the main location that the energy is wasted. The economic benefit of gas-lift well will decide that of the gas-lift system. The pipeline between gas-lift well and metering station play a role of moving energy, but the back pressure in the metering station is relevant to the wellhead back pressure, so it will affect the work of the gas-lift well.As the rod pumping system, the four parts of gas-lift system is divided and each part is much complicated and flow law is not same in any two parts. How to value the energy consumption of each part, on the results how to take aimed measures to improve the efficiency of gas-lift system and how to get max economic benefit on the condition of limited gas resource is the critical technology of gas lift.By describing energy conversion of four parts, a series of energy index is established. Computation on the test data from Wendong field indicates energy consumption and based on the statistic analysis aimed measures is taken to improve the efficiency os gas-lift system. Because the energy loss of gas-lift well is more than the others, much attention is paid to the measures of gas-lift well: to high-productivity well, the optimized design is used; to those wells with low productivity and low bottom-hole producing pressure, the plunger gas lift and new pig lift with one pipe string is advised. Based on the study of individual well, the optimized mathematic model is established to get max oil production and max economic benefit. So the gas resource is used in reason, In this thesis, the main achievements and recognitions is as follows:(1) Mathematic model of the efficiency of gas-lift systemIn this thesis, the gas-lift system is comprised of gas-lift pumping plant, gas distribution network, gas-lift well, and pipes between gas-lift well and metering station. Mathematical model is established to describe flow rule of four parts and the method to calculate theefficiency is given. As a result, a series of index is made. Combined with the economic benefit of gas-lift well, control chart of gas-lift well is built. Computation on the test data from Wendong field indicates that the proposed model performs well. The efficiency and energy consumption of the four parts are analyzed by statistics. What is more, the factors that affect the efficiency of gas-lift well are analyzed such as injection gas volume, injection gas/liquid ratio, injection pressure etc. It indicates that the slip loss in gas lift well is the main factor, which make the efficiency of gas-lift well and that of gas-lift system low. The measures to improve the efficiency of gas-lift system focus on how to make the efficiency of gas-lift well high.(2) The measures to improve the efficiency of gas-li...