煤层气直井间接压裂施工的先导地质分析

Pilot geological analysis of indirect fracturing in vertical CBM well

为了解决在构造煤发育区及其它煤质分布地区,有效利用煤层顶底板间接压裂工艺技术,以提高煤层气单井产量。从煤粉形成机理、裂缝形成机理以及压裂液滤失机理出发,开展了适用于间接压裂的储层先导性地质分析。分析结果表明,间接压裂工艺适用于容易产生煤粉、裂隙系统发育、缝高易失控的煤层;结合地应力场、岩性以及应力剖面特征,详细阐述了如何开展间接压裂设计。根据山西沁水盆地某区块资料,对比了地质条件相同的两口相邻煤层气井的压裂效果,间接压裂比常规压裂增产效果更明显,体现出间接压裂在改造煤层气解吸和产出流动通道方面的优势。

The indirect fracturing approach in coal seam roof and floor has been efficiently used in areas of devel-oped tectonic coal and other coal to enhance the production of single well. The pilot geological analysis of coal reservoir was carried out on the basis of the formation mechanism of pulverized coal and cracks, the mechanism of fracturing fluid leak-off . The results indicated that indirect fracturing was suitable for coal seams with developed fracture system easy to produce pulverized coal and to be out of control of fracture height. Combined with the characteristics of ground stress field, lithological section and stress profile, the paper described in detail how to carry out the design of indirect fracturing. Based on the data of a block in Qinshui basin, Shanxi Province, the fracturing effect of two neighboring wells of similar geological conditions was compared as an example, the yield-increasing effect of the indirect fracturing was better than that of the conventional fracturing, showing that the advantages of indirect fracturing in transformation of coalbed methan desorption and production of gas flow path.