川西超深高含硫气藏水平井完井技术

Horizontal well completion technology in ultra-deep and high-sulfur gas reservoirs in western Sichuan

川西气田雷口坡气藏具有埋藏深、温度高、高含硫、非均质性强等特征,超深、小井眼、长水平段等复杂井况导致投产管柱的安全下入、长水平段的有效改造、高含硫气井的安全测试投产面临巨大考验。通过对管柱下入影响因素分析、长水平段均匀布酸管柱设计、含硫气井环保测试工艺等研究,形成了以“反演分析+静止模拟”为主的超长水平井管柱下入方法、“多级滑套定点”的五联作一体化投产管柱、“密闭排液系统+放喷口喷淋喷火”为核心的环保测试技术。现场成功应用6井次,实现了8000 m井深、2000 m以上裸眼段的投产管柱安全下入,水平段分级作业能力达到10级,满足了施工压力95 MPa、排量7 m^(3)/min以内的酸化改造要求,测试平均无阻流量222.89×10^(4)m^(3)/d,较前期提高64.56%,测试返排液pH值大于7,H_(2)S浓度小于10 ppm,达到了川西气田长水平井测试投产目的。该技术有利于提高单井产量,满足环保测试要求,为类似气藏的开发提供借鉴。

The Leikoupo gas reservoir in the Western Sichuan Gas Field is characterized by deep burial,high temperature,high sulfur content,and strong heterogeneity.Complex well conditions such as ultra-deep wells,small boreholes,and long horizontal sections pose significant challenges for the safe installation of production tubing,effective stimulation of long horizontal sections,and safe testing and production of high-sulfur gas wells.Through the analysis of factors affecting tubing installation,the design of uniformly distributed acid tubing in long horizontal sections,and the development of environmentally friendly testing techniques for high-sulfur gas wells,a set of methods and technologies were developed,including“reverse analysis+static simulation”method for the installation of tubing in ultra-long horizontal wells,five-joint integrated production tubing system with a“multi-stage sliding sleeve fixed point”design,and environmental friendly testing techniques with“closed drainage system+nozzle spray and fire spray”as the core.This technology was successfully applied in the field for 6 wells,achieving safe tubing installation at depths of over 8000 m,including open section of over 2000 m in length.The ability to perform staged operations in the horizontal sections reached up to 10 stages,meeting the requirements for acid treatment with a working pressure of up to 95 MPa and a flow rate of up to 7 m^(3)/min.The average open flow rate during testing reached 222.8904 m^(3)/d,with an increase of 64.56%compared to previous stages.The returned liquid during testing had a pH value greater than 7,and the H_(2)S concentration was less than 10 ppm.This technology achieved the testing and production goals for long horizontal wells in the Western,Sichuan Gas Field,and it is beneficial for increasing individual well production,which meets the environmental testing requirements,can serve as a reference for the development of similar gas reservoirs.