库车坳陷巴什基奇克组深层有效储层成岩演化序列

Diagenetic paragenetic sequence of Bashijiqike Formation effective reservoir in Kuqa Depression

深层储层成岩演化过程复杂,精确成岩序列的建立有助于认识储层形成、演化过程及机理。选取库车坳陷巴什基奇克组作为研究对象,通过薄片观察、扫描电镜、阴极发光、流体包裹体及有机荧光等手段,系统分析成岩演化序列。结果表明:成岩演化过程包括压实作用、胶结作用、溶蚀作用、交代作用以及破裂作用;同生-早成岩A阶段,碱性成岩流体导致泥晶方解石、石膏、赤铁矿和蒙脱石形成;表生成岩阶段,构造裂缝发育,大气水淋滤导致长石和岩屑等矿物溶解,石英次生加大和高岭石形成;早成岩B阶段,碱性成岩流体导致亮晶方解石形成,高岭石向伊利石和绿泥石转化,以及石英溶蚀作用;中成岩A-B阶段,构造裂缝发育,大量有机酸注入导致长石和岩屑溶蚀,以及石英次生加大形成。因此,深层储层储集物性受控于多阶段成岩作用的叠加耦合作用。

The foundation of precise diagenetic paragenetic sequence contributes to analyzing the formation and evolution of deep reservoir with complex diagenetic processes.The paper studies Bashijiqike Formation in Kuqa Depression in order to reveal systematically the diagenetic paragenetic sequence by the means of thin sections,scanning electronic microscope,cathode luminescence,fluid inclusions and organic fluorescent.The result shows that the deep reservoir experienced compaction,cementation,dissolution,replacement and fracturing.During the stage A of the early diagenesis,alkaline diagenetic fluids lead to the formation of micrite calcite,gypsum,hematite and smectite.During the epidiagenesis,the leaching of meteoric water can dissolve feldspar and lithic fragment,leading to the formation of quartz overgrowth and kaolinite,and a lot of structural fractures can be observed.During the stage B of the early diagenesis,the formation of sparry calcite,the transformation from kaolinite to illite and chlorite and the dissolution of quartz can be observed under the alkaline diagenetic fluids environment.During the stage A-B of the middle diagenesis,the emplacement of organic acid along structural fractures can dissolve feldspar and lithic fragment,which can promote the formation of quartz overgrowth.Therefore,the quality of deep reservoir is controlled by the interaction of multi-stage diagenetic processes.