川中排水井MXX210井井口装置安全评价技术

Safety Evaluation Technology of Wellhead Device in Middle Sichuan Drainage Well MXX210

摘要: 随着龙王庙组气藏开发工作的推进，水侵风险日益明显，部分井区采取主动排水的治水对策。排水井因产水量大，井口装置因冲蚀造成壁厚减薄；且流体流动形态较为复杂，井口装置受到复杂载荷作用。为保障排水井井口装置的安全运行，利用FLUENT流场分析软件、ABAQUS有限元软件开展研究，以寻找不同产水量工况下，排水井井口装置疲劳失效规律。在FLUENT流场分析软件中，建立井口内流道三维模型、设定边界条件，找出内流道流动速度、压力变化规律以及流体对壁面作用力变化规律；根据流场分析结论，在FLUENT流场分析软件中，建立井口装置模型、设定边界条件以及工况载荷，揭示不同产水量下井口应力、应变情况；求解应力应变、疲劳寿命关系。结果表明，排水井最大应力、最大应变随产水量呈线性变化趋势，日产水量800方时，井口最大应力小于材料屈服强度，井口装置满足安全要求。

Abstract: With the development of gas reservoirs in Longwangmiao Formation, the risk of water invasion be-comes more and more obvious. Active drainage is adopted in some well areas. Due to the high water production of the drainage well and the erosion of the wellhead equipment, the wall thickness is reduced; Moreover, the fluid flow pattern is complicated, and the wellhead device is subjected to complex load. In order to ensure the safe operation of the wellhead device of the drainage well, FLUENT flow field analysis software and ABAQUS finite element software were used to carry out re-search, so as to find the fatigue failure law of the wellhead device of the drainage well under differ-ent water production conditions. In the flow field analysis software FLUENT, the three- dimensional model of the wellhead inner flow passage was established, boundary conditions were set, and the flow velocity and pressure change law of the inner flow passage and the force change law of the fluid on the wall were found out. According to the flow field analysis results, the wellhead device model, boundary conditions and working load were established in FLUENT flow field analysis software to reveal the wellhead stress and strain under different water yields. The relationship between stress-strain and fatigue life was solved. The results show that the maximum stress and strain of the drainage well change linearly with the water production. When the daily flow is 800 cubic meters, the maximum stress of the wellhead is less than the yield strength of the material, and the wellhead device meets the safety requirements.