含煤盆地煤储层后期改造形式及对煤层气选区影响——以华北克拉通选区为例
Reformed pattern of coal reservoirs in reformed coal basins and effect on favorable blocks of coalbed gas in the North China craton
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摘要: 阐述了改造型含煤盆地煤储层被改造的两种形式;煤体结构的改造及构造煤的形成原因;后生充填物对煤层孔隙的改造及形成原因。提出了以构造煤发育程度作为改造型含煤盆地改造强度的一个指标。概述了华北克拉通盆地由中生代剪压应力转化为新生代剪张应力和拉张应力,而在盆地内形成以挤压构造为主到伸展构造为主的演化历程,及不同构造类型的区域分布,指出这种演化极易形成构造煤和后生充填物。提出将华北克拉通含煤盆地分为 3种改造类型及其分布区域,分析了各自区域的煤储层物性及对煤层气开发选区的影响。提出应重视鄂尔多斯盆地侏罗纪煤层的煤层气研究与开发。Abstract: Two patterns of reformed coal reservoirs in reformed coal basins, the reformation of coal structure and reformed fracture by aposedimentary fillings and forming of the fillings are introduced. A new criterion of structural coal is proposed to judge the reformed degree of coal basins. Evolution of compressional structure in Mesozoic to extensional structure in Cenozoic and area of different types of structures in the North China craton are summarized. The results indicated that this type evolution is easy to form the structural coal and aposedimentary fillings. Three reformed structural types and each area in the North China craton are put forward, the property of coal reservoirs and their effect on favorable blocks of coalbed gas are analyzed. The study and examination of coalbed gas of Jurassic coal in Ordos basin should be emphasized.