陆相断陷盆地深部碎屑岩成岩演化及控制因素:以东营断陷盆地古近系孔店组为例

通过岩石薄片、扫描电镜、镜质体反射率、X衍射、物性分析等资料,对东营断陷盆地古近系孔店组成岩演化及控制因素进行详细研究。研究结果表明:东营断陷盆地孔店组典型成岩现象有强烈压实作用、硬石膏胶结、多期次碳酸盐胶结、多期次粘土矿物胶结、硅质强烈胶结、矿物强烈穿插交代、碎屑颗粒和胶结物的溶解作用;其中,压实作用是引起深部碎屑岩强烈致密化的主要原因;硬石膏胶结、碳酸盐胶结、硅质胶结是引起致密化的又一重要原因;长石、碳酸盐胶结物的溶解作用是引起该地区储层改善的主要成岩因素;成岩演化经历了准同生期-中成岩B期,部分达到晚成岩期的演化过程,成岩演化过程控制了深部碎屑岩孔隙演化;并推断原始干旱-半干旱沉积环境、基准面变化、深埋藏环境、构造-岩浆活动是控制成岩及孔隙演化的主要因素。

Diagenetic Evolution and Controlling Factors of Deep-seated Clastic Rocks in Terrestrial Fault-depressed Basin:Taking the Kongdian Formation of Dongying Fault-depressed Basin for Example

Based on the analysis of thin-section analysis,scan electricity microscope observation,vitrinite reflectance,X-diffraction and physical quality analysis,the diagenetic evolution and controlling factors of Kongdian Formation in Dongying sag have been detailly researched.It is indicated that the typical diagenetic phenomenon include the intensive compaction,anhydrite cementation,multiperiod carborate cementation,multiperiod clay minerals cementation,intensive siliceous cement,intensively interpenetration replacement between minerals,solution of clastic and cementation.The conclusion has been verified that compaction is the main cause of high pyknosis of the deep-seated clastic rocks,another cause is the cementation of anhydrite,carborate and siliceous.Solution of feldspar and carbonate cementation are the main diagenetic cause of improving the reservoir.Diagenetic evolution experiences the penecontemporaneous-middle diagenetic stage B,part of it reaches the late diagenetic stage.The diagenetic evolution controls the pore evolution.It has been discussed that aridity-semiarid depositional environment,locating surface variation,deep-burial,and tectonic-magma activity are the key factors of controlling the diagenetic evolution and pore evolution.