体积压裂技术在煤层气开采中的可行性研究

中国煤层气储量丰富，但由于煤储集层低饱和度、低渗透率、低压力等特点使煤层气井的开采效率极低。为了获得煤层气的高效产出，借鉴北美页岩气藏体积压裂改造工艺的成功经验，从天然裂缝发育程度、岩石成分和缝网构造机理3个方面提出了体积压裂的控制条件，对比了煤层气与页岩气的勘探技术和地质特征等，针对性地剖析了体积压裂技术在煤层气开发中的有效性与局限性。研究结果指出，体积压裂改造工艺技术可明显改善煤储集层的渗流环境，提高单井产量；其增产改造效果与煤储集层内天然裂缝、节理与层理等结构薄弱面的发育程度、岩石的脆性指数和水平主应力差值等密切相关；在压裂工艺允许的范围内，压裂改造体积越大，增产效果越显著。用MEYER软件数值模拟了山西临汾煤层气井组的一口井，结果表明，在煤储集层内实施体积压裂技术是可行的，这对今后煤层气的开采研究具有重要的指导意义与现实价值。

Feasibility Study on Application of Volume Fracturing Technology to Coalbed Methane (CBM) Development

China is rich in coalbed methane (CBM) reserves, but the production efficiency is very low due to the occurrence state, unique output mechanism, low CBM saturation, low permeability, low reservoir pressure and high CBM content. In order to get high recovery of CBM, this paper uses the successful experiences of North American shale gas pools development by volume fracturing process for reference, proposes the control conditions for volume fracturing in natural fracture, rock composition and fractural network structural mechanism, presents the similarity between CBM and shale gas in exploration approach and geological feature, and analyzes the validity and locality of the volume fracturing technology application to CBM development. The study results show that the volume fracturing process can be used to greatly improve the flow environment of coal reservoir and increase production; the incremental or stimulation response is closely related with the degree of development of natural fracture, fissure and bedding in a coal reservoir, rock brittleness index and horizontal principal stress difference, etc. Within the scope of such a fracturing process permissibility, the greater the volume modified, the more significant the stimulation response. In case study, this paper uses MEYER software to simulate a well in CBM well group in Linfen of Shanxi province, and the result indicates that the application of volume fracturing process to the coal reservoir for CBM development is feasible, which is of great significance and practical value for domestic CBM development and studies in the future