塔里木盆地克深区巴什基奇克组砂岩成岩演化及主控因素

Diagenetic evolution and major controlling factors for sandstone in Bashijiqike Formation of the Keshen Area in the Tarim Basin

塔里木盆地克深地区下白垩统巴什基奇克组致密砂岩储层的成岩作用直接控制着储层致密化程度,进而制约着库车气藏的形成。针对研究区成岩作用影响因素不清的问题,基于储层物性、录井等资料,结合区域地质背景、构造演化史研究,运用铸体薄片、阴极发光、扫描电镜、流体包裹体等实验观察方法,对该区储层成岩作用类型及影响因素进行了研究。结果表明:克深地区巴什基奇克组致密砂岩储层主要经历了压实、压溶、胶结、交代、溶蚀以及破裂作用,现处于中成岩B期;成岩作用主要受构造、沉积以及流体充注等因素共同控制,构造作用为主控因素,沉积环境有补充作用,流体充注影响较小;构造运动宏观上控制着储层物性、沉积成藏环境、埋藏演化以及流体充注等多个过程。该研究对克深地区气藏的有效储层物性下限计算、储层致密史恢复等均具有一定的指导意义。

Diagenesis of tight sandstone reservoir in Lower Cretaceous Bashijiqike Formation of Keshen Area in the Tarim Basin may directly control tightness of the reservoir, and eventually may restrict formation of the Kuqu Gas Reservoir. There are certain uncertainties in influencing factors for diagenesis in the Study Area. Accordingly, reser- voir physical properties, logging data, together with regional geologic background, tectonic evolution history have been used to determine reservoir diagenesis types and relevant influencing factors through casting thin-section, cathode luminescence, scanning electron microscope （SEM） , fluid inclusion and other techniques. Research results show tight sandstone reservoirs in Bashijiqike Formation of the Keshen Area experienced compaction, pressolution, cementation, alternation, dissolution and rupture. Currently, these reservoirs are in Middle diagenetic stage B; Di- agenesis processes are subject to joint controls of structure, sedimentation, fluid charging and other elements. A- mong them, tectonization is the most important controlling factor, sedimentary environment may play some supple- mentary roles, whereas fluid charging displayed the least impacts ; Macroscopically, tectonic movements may control reservoir physical properties, sedimentary environment, reservoir evolution, fluid charging and various other proces- ses. Relevant research results may provide necessary guidance for determination of lower limits in physical properties of effective gas reservoirs in the Keshen Area. In addition, these research results may also facilitate restoration of tightening history of relevant reservoirs.