The prediction of structural fractures in coal seams of the Kuba coalfield, China: an application for coalbed methane (CBM) recovery development

摘要

The structural fracture system in a coal reservoir enables coalbed methane (CBM) percolation and migration. It plays an important role in CBM exploration and exploitation (recovery) development. Nearly vertical strata with Mesozoic bituminous coal seams in the central part of the Kuba coalfield of the Xinjiang Province in China were studied using large-scale mapping of the structural fractures on the surface, and a using a technique for comparing and analyzing sections of the underground coal mine. This investigation verified that similar structural fractures are developed in the underground coal seams as those on the surface, and surrounding rocks represent the same tectonic layer. Meanwhile, a corresponding relationship between the characteristics of the development of fractures -including the growth directions and degree of development of fractures in coal seams and the surrounding rocks -was established. Based on this, the research presents a new method for predicting a pattern of fractures in coal seams and the coal structure, respectively. Finally, the study area was divided into zones with dense, moderate and un-developed fractures. The method should be applicable in various coal-and-gas engineering fields, for example the prediction of fractured zones in coal seams, the prediction of coal structure, and for projecting the well arrangement in the exploration and development of economic recovery of CBM.