川渝地区含硫深井气举技术研究及应用

Air lift technologies and their application to deep sour gas wells,Sichuan-Chongqing area

深层碳酸盐岩气藏占四川盆地天然气资源的59%,已开发气藏普遍受水侵影响,气藏具有埋藏深、高温、高压、含硫、井筒条件复杂等特点,导致气举技术在该类气藏中应用时面临设计方法缺失,工具性能不足等系列问题。针对上述问题,通过优化设计方法、研制高压气举阀及排水采气工具等技术攻关,并进行实际应用,形成了高压深井气举、免修井排水采气等一系列含硫深井排水采气新技术。研究成果表明:(1)在常规气举设计基础上,引入地层吸液指数,建立基于地层—井筒耦合流动的高压深井气举设计方法,该方法增加顶阀下入深度,气举阀布阀支数减少60%,降低阀间干扰;(2)通过气举阀结构优化设计,研制了充氮压力35 MPa、抗外压90 MPa的高压耐蚀气举阀,可满足6 000 m井深范围内酸化—气举联作和井下长期工作的需求;(3)设计以单向注入通道为核心的气举封隔器构建单向工艺通道,以自验封和悬挂为核心的气举封隔器重建工艺通道,研发了预置式、隔离式、跨隔式排水采气工具,满足永久式封隔器在气井完井不同阶段开展排水的技术需求,实现免修井排水采气。在川渝地区含硫深井中现场应用300余井次,应用井深超6 000 m,最大排水量达650 m~3/d,有效地解决了川渝地区气田含硫、高压、深井排水采气问题。

Deep carbonate gas reservoirs are dedicated to 59%of natural-gas resources in Sichuan Basin.Widely affected by water in-vasion,the developed reservoirs feature high temperature and pressure,sulfur occurrence and complex wellbore conditions in addition to deep burial depth,leading to difficulties in their air lift,like shortage of design methods and tools in poor performance.Thus,covering air lift in deep wells with high pressure and drainage gas recovery without any workover,a series of new technologies of drainage gas recovery have been created for these deep sour gas wells after plenty of technical breakthroughs and practices on the design optimiza-tion,prepared high-pressure lift valve and drainage gas recovery.Results show that(i)consulted the design of conventional air lift and introduced the liquid absorption index,a method of air lift is built for deep wells with high pressure based on coupled formation-bore-hole flow.It may increase top valves in the depth of setting,reduce both lift and laying-out valves by 60%,and eliminate interference between valves;(ii)with the nitrogen-charged pressure of 35 MPa and the resistance to external pressure of 90 MPa,a high-pressure and corrosion-resistant lift valve is manufactured by valve optimization,which meets the requirements of combined acidizing and air lift together with long-term downhole operation at the well depth less than or equal to 6,000 m;and(iii)one gas lift packer with one-way injection channel as the core is planned to construct one-way process channel,and then the other packer with self-sealing and sus-pension as the core is also mapped out for this channel reconstruction.And the developed preset,isolated and span-separated drainage gas recovery tools meet technical demands of water drainage when permanent packers are used in different stages of completed wells,and drainage gas recovery without workover comes true.These air lift technologies have been applied to more than 300 deep sour gas wells in Sichuan-Chongqing area,whose the depth excesses 6,000 m and the maximum displacement of 650 m3/d,respectively.They can solve problems on the drainage gas recovery in deep sour wells with high pressure in this area.