煤层气成藏的构造应力场研究

构造应力场是控制煤层气成藏极为重要的因素，深入探讨不同性质构造应力场对煤储层的改造及控制机理，将会为煤层气勘探前景评价提供重要的理论基础．本文在区域构造应力场研究的基础上，分别探讨了不同性质构造应力场的作用特征及其对构造发育、构造展布、构造组合及构造变形的控制作用；分析了不同性质构造及其组合、应力-应变环境对煤储层的改造作用，探讨了不同变形机制和不同结构构造煤在不同构造应力场中的发育及展布规律．研究表明，挤压应力场作用下，在强变形带的中心及其附近，可以形成糜棱煤类构造煤，但糜棱煤分布较为局限；在较大范围内形成脆性变形系列的构造煤，是煤层气勘采的有利区带；拉张构造应力场中，大部分区域内有利于煤层裂隙的形成和渗透率的提高，但易造成煤层气的散失，含气量降低，应重视有利的储气构造的研究．剪切构造应力场中，以平移断层为界，煤层的赋存状态、煤体结构和煤储层物性都会存在一定的差异，应对不同的构造单元分别研究其煤储层特征．

Research on Tectonic Stress Field of Generate and Reservoir of Coalbed Methane

Tectonic stress field is a very important factor on controlling of reservoir of coalbed methane(CBM), the fundament for evaluating exploration foreground of CBM can be provided from study on reforming and controlling mechanism of tectonic stress fields of different characters to coalbed reservoir. Based on research of regional tectonic stress field, the action characteristics of tectonic stress fields of different kinds and their controlling function to development, distribution, combination and deformation of structures were discussed,respectively. The reforming action of different characters and combinations of structures and environment of strain-stress to coalbed reservoir have been analyzed. The development and distribution orderliness of different tectonic coals that have unlike deformation mechanisms and textures in dissimilar tectonic stress fields have been also discussed. Mylonitic coal may develop in the center of strongly deformational belt in pressing tectonic stress field. Since mylonitic coal is limited in a narrow area, biggish area in that tectonic coals of brittle deformation distribute is favorable for CBM exploration. Most of areas are advantageous for formation of coalbed fractures and increase of permeability in extension stress field, but it is easy to beget dissipation of CBM and decrease of gas content. Therefore, study of structure of gas reservoir should be taken seriously. There is a different of occurrence estate of coalbed, texture of coalbody and physical property of reservoir beside both walls of strike-slip fault in shear stress field, the characteristics of coal reservoir of unlike structural units should be researched, respectively.