川渝气田大斜度水平井排水采气工艺优化

Drainage gas recovery technologies for highly deviated horizontal wells and their application to many gasfields in Sichuan-Chongqing area

针对川渝气田大斜度水平井排水采气过程中存在的出水井因气藏埋藏较深、井下管串结构复杂易造成泡排剂适应差、固体泡排剂投注遇阻,打孔气举启动压力与连续注气压力差值过大易造成地面设备效率低下等问题,提出了排水采气工艺优化措施并进行了应用评价。研究结果表明:①优化方案一方面借鉴直井排水采气经验,通过研制液体泡排剂、优化泡排加注方式,提高了泡排效率,另一方面通过引入地层吸液指数优化气举设计方法,实现了增加注气深度、最大化利用地面注气设备的目的;②所研制的新型液体泡排剂E是一种适应大斜度、水平井生产特点的高效泡排剂,具有耐高温、高矿化度、高酸性气体的特点。通过现场试验,证实优化后的泡排工艺技术能够显著提高泡排效果,经引入地层吸液指数进行优化后形成的深井气举设计技术,可提高举升效率,使气水井快速复产,降低作业成本。

When some technologies of drainage gas recovery are adopted to highly deviated horizontal wells in most gasfield, Sichuan-Chongqing area, both great burial depth of gas reservoirs and complex structure of downhole pipe string may lead to poor adaptability of foaming agent and difficult injection of solid foaming agent into these wells with water breakthrough;moreover, a large difference between threshold pressure of slotting gas lift and pressure of continuous gas injection may decrease an efficiency of ground equipments. So, a method for optimizing the drainage gas recovery technologies was put forward and its application was evaluated. Results show the optimization scheme is composed of two parts, including to develop a liquid foaming agent and optimize its injection mode by some experience on its application to vertical wells, and to introduce a gas lift design optimization method with formation imbibition index to achieve one target to not only increase an injection depth but also maximize a utilization of ground gas-injection equipments;and(2) field tests prove that the optimized foam drainage technologies can improve an effect of foam drainage remarkably, and the optimized deep-well gas lift design technologies with formation imbibition index can increase the lift efficiency, realize fast restoration of gas wells with water breakthrough, and reduce operation cost.