沧东凹陷南皮斜坡孔二段致密砂岩储层特征及优质储层形成机理

Characteristics of tight sandstone reservoir and formation mechanism of high quality reservoir in second member of Kongdian Formation,Nanpi slope,Cangdong sag

为加快南皮斜坡致密油勘探开发部署,实现高效产油,综合开展9口井268块岩心扫描电镜、铸体薄片与恒速压汞等物性资料分析,通过开展沉积、成岩及其与储层物性之间相关性研究,明确储层性能影响因素,开展成岩演化模式构建。结果表明,研究区长石砂岩和岩屑长石砂岩占比较大,孔隙度小于10%、渗透率小于1 mD为首要储层;沉积、成岩作用为致密储层主要影响因素,其中砂体分选好的水下分流河道为优质致密储层发育区;成岩早期压实作用导致储层的低孔、低渗性,胶结作用抑制储层物性发育,致使早期储层致密化,成岩中期较强溶蚀作用促进次生孔隙发育,极大改善储层物性,绿泥石黏土薄膜发育抑制石英次生加大,对渗流通道起到保护作用。

In order to accelerate the deployment of tight oil exploration and development in Nanpi slope and achieve high-efficiency oil production,comprehensive analysis of 268 core casting thin slices,scanning electron microscopy and constant-rate mercury intrusion were carried out in 9 wells.Research is carried on reservoir physical properties,influencing factors of reservoir performance,and the construction of diagenetic evolution model.The research shows that the rock types in the study area are dominated by feldspar sandstone and lithic feldspar sandstone,with porosity less than 10%and permeability less than 1 mD accounting to heavy proportion.Sedimentation and diagenesis are the main influencing factors of tight reservoirs in the study area.Among them,the underwater distributary channel with good sand body sorting is a high-quality tight reservoir development area.The compaction in the early stage of diagenesis leads to low porosity and low permeability of the reservoir,and cementation inhibits the development of the physical properties of the reservoir,resulting in early reservoir densification.The strong dissolution in the middle stage of diagenesis promotes the development of secondary pores and greatly improves the physical properties of the reservoir.The development of the chlorite clay film inhibits the secondary growth of quartz and protects the seepage channel.