800m以深直井煤储层压裂特征分析

以沁水盆地800 m以深煤层气井为例,统计归纳了深部煤层地质特征,分析了与之对应的压裂难点;通过统计10口采用活性水压裂技术且产气效果显著提升的深煤层气井的压裂数据,总结了现有技术体系下深煤层直井压裂施工参数特征,分析了导致深部煤层气藏压裂施工中压力异常偏高的因素,提出了深部煤层气藏开发对策。结果表明:深部煤层气藏的高温、高压、高地应力的地质环境、较差的储层物性以及较强的非均质性等特征,使得现有压裂技术体系在适用性和有效性上面临严峻挑战;增产效果较好的深部煤层气直井,普遍采用大液量注入,同时控制砂比在15%左右;压裂时压力异常偏高是受到压裂液性能、地层微裂缝、储层岩性、钻井液污染及煤粉堵塞等因素的影响;未来应对深部煤层气藏的开发,除了要对活性水压裂技术进行优化,还有赖于压裂理论的发展和新型压裂材料的研制。

Fracturing characteristics analysis of 800 meters deeper coalbed methane vertical wells

In this study,the samples were taken from the wells of Qinshui Basin with depth more than 800 meters.Geological features of deep coal seam were summarized.The fracturing difficulties were also analyzed.According to the statistics of fracturing data from 10 deep wells,which used active water fracturing technologies and obtained some good effects,the characteristics of fracturing construction parameters for deep CBM wells using the existing technologies were summarized.The factors that cause the abnormal high pressure of fracturing in deep coal bed gas reservoir were analyzed.The strategies of deep coalbed methane reservoir were proposed.The research results show that deep coal beds have high temperature,high pressure,high ground stress,poor reservoir physical properties and strong heterogeneity,which makes the applicability and validity of the existing technologies face severe challenges.The vertical well fracturing uses large volume injection and 15% sand ratio.Abnormal pressure of fracturing is influenced by fracturing fluid properties,the formation of micro fractures,reservoir lithology,drilling fluid pollution,coal blockage and other factors.The development of deep coal beds in the future depends on not only the optimization of active water fracturing technology,but also the promotion of fracturing theories and the development of new materials.