同心管复合排水采气工艺技术

Combined drainage gas recovery technology based on concentric pipe

克拉美丽气田是具有1 000×10~8 m^3储量的大型火山岩气田,气田水平井采用?114.3 mm或?139.7 mm大尺寸管柱携带裸眼封隔器进行多级压裂改造求产,但在气井生产的中后期,随着气井产能下降,产水量上升,出现携液困难,导致气井被迫关井或间开。采用同心管复合排水采气工艺技术下入带有气举阀的小管柱:(1)根据原井的管柱结构和基本数据,优选出下入的小管柱尺寸;(2)设计的偏心式等通径气举阀工作筒,既保证气举阀牢固安装,防止气举阀磕碰,又在工作筒外形允许范围内尽可能地放大内部通径,使之与所连小管柱内径基本相等,减少或避免了节流的影响;(3)设计了专用的气举阀,优化气举阀结构和尺寸以配套气举阀工作筒;(4)用两级油管头隔开内外管空间,对气井进行气举以复产,内管可实现气井的稳定生产。现场应用实践证明,同心管复合排水采气工艺技术适用于裸眼完井水平井的中后期生产阶段,可改善气井的开发效果,有效提高气井累产气量,为同类型井的排水采气生产提供了技术思路。

Kelameili Gas Field is a large-scale volcanic gas field with reserves of 1 000×10^8 m^3. In this gas field, multi-stage fracturing stimulation of horizontal well is conducted by using the large-size string （Φ114.3 mm or Φ139.7 mm） to carry open hole packers. In the middle and late production stage of gas wells, however, water production rate rises with the decline of gas well productivity, and liquid carrying gets difficult, so the gas wells have to be shut down or opened intermittently. To solve this problem, the small string with gas lift valve was lowered by means of the combined drainage gas recovery technology based on concentric pipe. First, the size of the small string to be lower was optimized according to the string structure and basic data of the original well. Second, eccentric iso- drift working barrel of gas lift valve was designed. By virtue of this working barrel, the gas lift valve is installed firmly and is prevent- ed from colliding. Besides, the internal drift can be enlarged as much as possible while the configuration of the working barrel is guar- anteed, so that it can be basically equal to the internal diameter of the small string connecting with it, and the effect of throttling can be reduced or avoided. Third, the dedicated gas lift valve was designed, and its structure and size were optimized to match its working barrel. And fourth, the two-stage tubing head was adopted to isolate the inner tubing from the outer tubing, and gas lift was used for the recovery of gas wells. And thus, the stable gas well production can be realized in the inner tubing. Field application proves that the combined drainage gas recovery technology based on concentric pipe is applicable to the middle and late production stage of horizon- tal wells with open hole completion. It can improve the development effect of gas wells and increase the cumulative gas production of gas wells. It provides the technical idea for the drainage gas recovery of similar wells.