CO驱低液量高气液比井下气锚模拟与优化

Simulation and Optimization of Downhole Gas-Liquid Separator at Low Liquid Rate and High GLR Wells From CO Flooding Reservoir

刘永辉 张楠 潘若生 张德平 王武兵

LIUYonghui ZHANGNan PANRuosheng ZHANGDeping WANGWubing

西南石油大学石油与天然气工程学院, 四川 成都 610500 中国石油吉林油田采油工艺研究院, 吉林 松原 138000 陕西延长石油国际勘探开发工程有限公司, 陕西 西安 710000

School of Petroleum and Natural Gas Engineering, Southwest Petroleum University, Chengdu, Sichuan 610500, China Production Technology Research Institute, Jilin Oilfield Company, PetroChina, Songyuan, Jilin 138000, China International Exploration and Development Engineering Company, Shaanxi Yanchang Petroleum Co. Ltd., Xi'an, Shaanxi 710000, China

注CO驱油已在吉林油田开发低渗透油藏中取得了良好效果，其采油井出现典型的小液量、高气液比特征，导致在常规油井中运行良好的有杆泵采油工艺出现了较强的不适应性。为此，在分析常规重力类气锚和螺旋气锚分气原理的基础上，设计了适用于低液量高气液比的新型井下气锚结构，采用抽油机悬点运动规律作为抽油泵工作过程，修正了CFD模型的上边界条件，将地面气液比修正为入泵气液比并考虑气泡的破碎和凝聚，模拟了新型井下气锚工作原理，单因素敏感分析了柱塞的抽汲参数对新型井下气锚分气效率的影响。X井现场试验表明，采用新型井下气锚后，井口套压由9.5 MPa降至0.4 MPa，产液量由措施前的1.5 t/d升至17.4 t/d，在产气量达到792 m/d情况下，泵效高达84.6%，明显高于同区块其余井平均泵效40.1%。该研究成果对于CO驱油的推广应用具有重要现实意义，对类似的高气液比油井有杆泵抽油具有重要的借鉴作用。

CO flooding technology was well applied in low permeability reservoirs in Jilin Oilfield, where production wells are characterized by small liquid rate and high gas liquid ratio, which has a serious effect on the sucker rod pump system, such as low pump efficiency. Aiming at dropping the gas rate pumped into sucker rod in those wells, we developed a new downhole gas-liquid separator on the basis of gas separation principle of the conventional gravity type gas anchor and that of spiral gas anchor. In this paper, CFD is improved to optimize its parameters. Suspended point motion of pump unitsis taken as boundary conditions of the motion pump, the surface gas-liquid ratio is replaced by the gas-liquid ratio and bubble breakage and aggregation are taken into consideration. The swabbing parameters of sucker rod pump were selected to get its high efficiency. The new downhole gas-liquid separator was installed at Well X. The casing pressure dropped from 9.5 MPa to 0.4 MPa, daily liquid production rate increased from 1.5 t/d to 17.4 t/d, and the pump efficiency was 84.6% when the daily gas volume rate is 792 m/d. Its pump efficiency is higher than the average pump efficiency of 40.1% of other wells in the same block. The study has important practical significance in application of CO flooding and has an important reference in similar high gas liquid ratio wells with sucker rod pump.

10.11885/j.issn.1674-5086.2014.12.15.03