【摘要】 东营凹陷北部沙四上亚段是重要的含油层系,其储层的形成过程和分布规律是近年来的研究难点和热点。通过对研究区样品进行偏光显微镜和荧光观察、扫描电镜分析,并结合区域构造演化史和有机质热演化史,研究东营凹陷北部沙四上亚段的固体-流体相互作用机制及其对储层物性的影响。结果表明研究区可划分出7个流体活动期次,其成岩环境的变化依次为碱性、酸性、碱性、酸性、碱性、酸性至酸碱交替。酸性流体与固体的相互作用表现为明显的碳酸盐溶解、长石溶解及石英的次生加大等,主要改善了储层物性;而碱性流体与固体的相互作用主要表现为石英的溶解、长石次生加大、铁方解石和(铁)白云石及硬石膏沉淀等,在很大程度上堵塞了孔隙,降低了储层物性。研究区共发生两次油气充注,为沙二段到东营组沉积时期以及馆陶组沉积末期,两次油气充注分别对应了两个次生孔隙发育带。更多还原

【Abstract】 In northern Dongying Sag,the reservoir formation and distribution of upper submember of the fourth member in the Shahejie Formation is the study focus in recent years. It is an important oil-bearing sequence. The solid-fluid interaction mechanism and its influence on physical properties of reservoirs could be studied by the observation of polarizing and fluorescence microscope and the analyses of SEM on thin sections in combination with regional tectonic evolution and thermal history of organic matters. Conclusions are drawn as follows. There are seven active fluid episodes in the variation of diagenetic environment,namely,alkaline,acidic,alkaline,acidic,alkaline,acidic and alternating alkaline and acidic setting,respectively. The interaction of acidic fluid and solid presents significant dissolution of carbonate minerals and feldspar,and quartz overgrowth to enhance the reservoirs; while the interaction of alkaline fluid and solid is characterized by quartz dissolution, feldspar overgrowth and the precipitation of ferrocalcite,ankerite and anhydrite,which largely infill pores and destroy the reservoirs. There are two hydrocarbon expulsion episodes,namely,the deposition period from the second member of Shahejie Formation to Dongying Formation,and the latest one of Guantao Formation. These two events are in correspondence with the development of two secondary pore zones.更多还原