韩城区块煤层气井二次改造工艺优化及现场试验

Optimization and Field Application of Secondary Stimulation Technologies for Coalbed Methane Wells in Hancheng Block

韩城区块煤层气井产能尚未完全释放,无法支撑长期稳产和高产。为进一步优化煤储层二次改造工艺,改造低产能煤层气井,提高煤层气单井产量,在剖析该区块地质特征的基础上,分析了常规二次压裂工艺试验井的低产原因。针对二次改造施工过程中的工艺缺陷及技术难题,以解决“煤粉堵塞裂缝+新裂缝延伸距离有限”为主要目标,形成了“酸化+暂堵”复合二次改造工艺,并在3口井进行了现场试验。采用复合二次改造新工艺后,试验井J4井平均产气量为3 765.6 m^(3)/d,产量提升明显,裂缝改造体积较为理想;J5井、J6井恢复生产能力,且上产潜力较大。研究结果表明,复合二次改造新工艺在低产能煤层气井应用效果较好,可为相同地质背景条件下的煤层气老井改造提供技术借鉴。

The productivity of the coalbed methane (CBM) wells in Hancheng Block has not been fully exploited resulting in a problem of failed stable and high production goals over the long term.To further optimize secondary stimulation technologies for coal reservoirs,stimulation of low-productivity CBM wells,and increase production of single CBM well,the geological characteristics of this block were analyzed,and the causes of the low production in the test wells after conventional secondary fracturing were explored.The main objectives of this research targeted the technical defects and difficulties during secondary stimulation,and solving the problem of“pulverized coal plugging fractures and limited propagation distance of new fractures.”Composite secondary stimulation technologies of“acidizing+temporary plugging”were developed and tested in the field in three wells.The results showed that after the composite secondary stimulation technologies were applied,the average gas production of Test Well J4 reached3 765.6 m^(3)/d,indicating that a significant production increase was achieved and that the stimulated fracture volume was satisfactory.In addition,the production capacity of Test Wells J5 and J6 recovered and demonstrated great production potential.With a favorable application effect in low-productivity CBM wells,the proposed composite secondary stimulation technologies can provide a technical reference for the stimulation of old CBM wells under similar geological conditions.