摘要
柱塞气举技术已成为国内外经济性较高的排液采气关键技术之一,但由于柱塞与油管内壁环缝间液体漏失和气体上窜降低了柱塞气举排液率甚至造成举升失败。因此,为优化柱塞气举结构以提高举升效率,构建了运动柱塞与油管内壁环缝间气液两相逆流数值模型,研究了柱塞结构与上行速度对环缝内气液逆流流型转变以及逆流密封性能的影响规律,揭示了柱塞与油管内壁环缝内的气液逆流密封机理,提出了强化气液逆流密封性能的最优上行举升速度与柱塞结构优化方向。研究结果表明:①在柱塞表面添加槽式结构可显著改善柱塞与油管内壁环缝间的气液逆流密封特性,且矩形槽柱塞举升效果优于梯形槽柱塞;②当矩形槽室宽度小于深度时,气液难以充分混合而呈气液分层流型,气相涡旋将液体挤压在槽内壁面,环缝内流体速度衰减较小,气液漏失量较大;③当矩形槽室宽度是深度的2倍时,槽内呈气液搅拌流型,出现两相涡旋并引起气液流速的衰减,减小了举升过程中的流体漏失;④柱塞平均上行速度为5 m/s时,槽式柱塞与油管内壁环缝间气液流动密封性能最佳。结论认为,选用槽室宽度是深度2倍的矩形槽柱塞并控制其举升速度趋近于5 m/s,可有效提高柱塞排液效率,该研究成果可以为柱塞气举排液技术优化提供技术支撑,有助于提高天然气采收率,为天然气的规模效益开发提供了理论依据。
Plunger lift has become one of the key drainage and gas recovery technologies with better economy at home and abroad,but the liquid leakage in the annular gap between a plunger and the inner tubing wall and the upward gas channeling lead to the reduction of drainage efficiency and even the failure of plunger lift.In order to structurally optimize plunger lift to improve the lift efficiency,this paper establishes a numerical model of countercurrent gas-liquid flow in the annular gap between a moving plunger and the inner tubing wall.The influences of plunger structure and upward traveling speed on the flow pattern transformation and sealing capacity of countercurrent gas-liquid flow in the annular gap are studied,and the sealing mechanisms of the countercurrent gas-liquid flow in the annular gap between the plunger and the inner tubing wall are revealed.In addition,the optimal upward lift speed and plunger structure optimization direction to enhance the sealing capacity of countercurrent gas-liquid flow are pointed out.And the following research results are obtained.First,the introduction of groove structure on the surface of the plunger can significantly improve the sealing capacity of the countercurrent gas-liquid flow in the annular gap between the plunger and the inner tubing wall,and the lift effect of the rectangular-groove plunger is superior to that of the trapezoidal-groove plunger.Second,when the groove width is smaller than the depth,gas and liquid cannot mix adequately but in the stratified flow pattern,and gas vortex extrudes liquid onto the inner wall of the groove.As a result,the flow velocity in the annular gap decreases,and more gas and liquid is lost.Third,when the width of the rectangular groove is twice the depth,the flow pattern in the groove is gas and liquid mixing,and two-phase vortex occurs,leading to the reduction of the gas and liquid flow velocity.As a result,the liquid loss in the lift process is reduced.Fourth,when the average upward traveling speed of the plunger is 5 m/s,the sealing capacity of the gas-liquid flow in the annular gap between the plunger and the inner tubing wall is optimal.In conclusion,plunger's drainage efficiency can be improved effectively by adopting the rectangular-groove plunger whose groove width is twice the depth and by controlling the lift speed to be about 5 m/s.The research results can provide a technical support for the optimization of the plunger lift and drainage technology,are conducive to the improvement of natural gas recovery and provide a theoretical basis for the large-scale benefit development of natural gas.
作者
赵昆鹏
田伟
张存社
杨云博
贾友亮
沈志昊
李鑫
白博峰
ZHAO Kunpeng;TIAN Wei;ZHANG Cunshe;YANG Yunbo;JIA Youliang;SHEN Zhihao;LI Xin;BAI Bofeng(State Key Laboratory of Multiphase Flow in Power Engineering,Xi'an Jiaotong University,Xi'an,Shaanxi 710049,China;Oil and Gas Technology Institute,PetroChina Changqing Oilfield Company,Xi'an,Shaanxi 710018,China;No.5 Gas Production Plant,Petro-China Changqing Oilfield Company,Xi'an,Shaanxi 710016,China;Changbei Gas Production Plant,PetroChina Changqing Oilfield Company,Yulin,Shaanxi 719100,China)
出处
《天然气工业》
EI
CAS
CSCD
北大核心
2023年第5期56-62,共7页
Natural Gas Industry
基金
国家自然科学基金杰出青年项目“多相流动与热传”(编号:51425603)。
关键词
排液采气
柱塞气举
气液逆流
两相涡旋
流动密封
液体漏失
气体滑脱
槽室
Drainage and gas recovery
Plunger lift
Countercurrent gas-liquid flow
Two-phase vortex
Flow seal
Liquid leakage
Gas slippage
Groove
