华北盆-山演化和岩石圈转型与煤层气富集的关系

以华北陆块盆-山构造与岩石圈岩浆热结构演化研究为基础,以区内不同富集机制的含煤区域为研究对象,对华北典型地区盆-山演化、岩石圈转型及其与煤层气富集的关系进行了深入探讨。研究表明,华北典型地区盆-山动力学过程从中生代开始经历了挤压盆-山阶段、挤压盆-山向伸展盆-山转换阶段以及伸展盆-山阶段;华北岩石圈结构演化则经历了岩石圈增厚与稳定过程、岩石圈转型过程、岩石圈快速减薄过程等,且自古生代以来至少经历了两次以上具有时空不均一性的岩石圈转型。沁水盆地和两淮煤田的构造—热动力学环境有利于煤层气富集,且在挤压与伸展作用的转换和叠加过程中形成的构造过渡带是煤层气富集的有利构造单元。沁水盆地煤层气富集特征是岩浆—热作用有利于煤层气储集,而一定的构造变形有利于煤层气的渗流和开采;两淮煤田的强构造作用和后期叠加的张性应力场有利于煤层气的富集和储层的增渗,可在构造煤发育区寻找煤层气开发的有利区域。

Basin-mountain Evolution,Lithosphere Transformation and Their Relationship with Coalbed Methane Accumulation in North China

This paper discusses the thermal-tectonic dynamic mechanism and control effects of basin-mountain evolution, lithosphere transformation and coalbed methane accumulation in the typical regions of North China on the basis of basin-mountain tectonic evolution and magma thermal structure. The research results shows that basin-mountain dynamic process in research area experienced compression, conversion from compression to extension, extension stages; meanwhile lithosphere structure evolution experienced thickening and stabilization, transformation, rapid thinning. According to the achievements available, lithosphere of north China experienced at least twice heterogenetic time-space transformation since Paleozoic era. Tectonic-thermal dynamic environment is favorable for coalbed methane accumulation, and the structural units in conversion from compression to extension and transition zones formed in the superimposed process are also beneficial to coalbed methane accumulation in Qinshui Basin, Huainan and Huaibei coalfields. The characteristics of coalbed methane reservoir in Qinshui basin are beneficial magma-thermal actions which contribute to accumulate coalbed gas and moderate tectonic deformation which is helpful for seepage; meanwhile in Huainan and Huaibei coalfields strong tectonic actions and later stage superimposed extensional stress filed are beneficial to accumulation of coalbed gas and seepage of coal reservoir, which means tectonic coal developed regions are promising area for exploring coalbed gas.