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为在歧口凹陷歧南斜坡深层砂岩中寻找优质储层,综合运用岩石薄片、铸体薄片、扫描电镜及物性等资料,对研究区储层成岩孔隙演化与次生孔隙的形成机制进行了研究,认为区内孔隙演化与成岩演化具有耦合关系,次生孔隙的形成机制包括优势沉积相带、溶蚀作用和异常高压.结果表明:深层砂岩储层为(特)低孔-特低渗型,成岩演化处于中成岩A1~A2亚期.机械压实、方解石胶结和石英加大是降低孔隙度的主要成岩作用,溶蚀作用是形成次生孔隙的建设性成岩作用,产生的次生孔隙可达10%.孔隙度高值区,有机质生烃高峰和蒙脱石含量低值区在同一深度出现.受成岩演化控制,埋深3 500~3 900m和4 400~4 700m发育2个次生孔隙发育带(孔隙度>12%),其平面上主要分布在三角洲前缘水下分流河道、河口砂坝和异常高压叠置区.根据岩性、物性和压力系数等参数将区内储层分为4类,Ⅰ~Ⅱ类储层是研究区的优质储层,也是今后增储上产的主要储层.
In order to search for high quality reservoirs in deep sandstone of Qiaonan slope in Qikou depression, the evolution mechanism of reservoir diagenesis and the formation mechanism of secondary pores were studied by comprehensively using such data as rock slice, cast slice, SEM and physical properties , Suggesting that there is a coupling relationship between pore evolution and diagenesis in the area.The formation mechanism of secondary pores includes dominant sedimentary facies, dissolution and abnormal pressure.The results show that the deep sandstone reservoirs are (special) low porosity-ultra low permeability type, Diagenetic evolution is in the metaplastic diagenesis A1 ~ A2. Mechanical compaction, calcite cementation and quartz enrichment are the main diagenesis to reduce porosity, and dissolution is the formation of secondary diagenetic diagenesis, and the secondary porosity 10% .In the area of high porosity, the hydrocarbon generation peak of organic matter and the low value area of montmorillonite occur at the same depth.Due to the diagenetic evolution control, there are two secondary pores with 3 500 ~ 3 900m depth and 4 400 ~ 4 700m depth Development zone (porosity> 12%) is mainly distributed in delta front subaqueous distributary channel, estuarine sand bar and anomalous high pressure superimposition area. According to lithology, physical property and pressure coefficient, For the four categories, Ⅰ ~ Ⅱ Class reservoirs are high-quality reservoirs in the study area and also the major reservoirs that increase production and yield in the future.