安塞油田Y区块长6储层孔隙特征及影响因素

采用普通薄片、铸体薄片、扫描电镜、x衍射及高压压汞等多种技术手段,对鄂尔多斯盆地安塞油田Y区块长6储层的孔隙特征进行研究,并结合储层的沉积环境、岩性特征和成岩演化过程对影响储层孔隙发育的因素进行了深入分析。结果表明,研究区长6储层岩性主要为长石细砂岩;孔隙类型以溶蚀孔及残余粒间孔为主;成岩演化目前均已达到晚成岩A期;沉积环境和成岩作用是影响储层孔隙发育的主要因素,不同的沉积微相直接影响储层砂岩的成分成熟度和结构成熟度的程度;压实作用是造成孔隙减小的主要因素;而碳酸岩、浊沸石等的胶结作用一方面降低粒间孔隙,一方面支撑骨架,增强储层抗压实能力,同时为后期的溶蚀作用产生次生孔隙提供了空间和物质基础;另外,溶蚀作用的多次发生,改变了孔隙结构,使得次生孔隙发育。

Characteristics of pore evolution and its controlling factors of Chang 6 reservoir in Y area of Ansai oilfield

Using ordinary thin sections,casting thin sections,SEM,X-ray diffraction,high pressure mercury and other technical means to study on pore characteristics of Chang 6 reservoir in Ansai oilfield, Ordos basin,and then combined with the sedimentary environment、lithologic feature and diagenetic evolution of the reservoirs to analyse deeply the factors that affected the reservoir porosity . The result shows that the lithologic of Chang 6 reservoir is mainly of feldspar fine sandstone;The main pore types of the reservoir include dissolution pores and residual intergranular pore;Diagenetic evolution has reached late diagenetic A stage;Depositional environments and diagenesis are major factors of reservoir porosity. Different sedimentary microfacies direct effect the degree of the composition maturity and structure maturity of the reservoir sandstones. Compaction is the main factors of pore reducing;on the one hand,the cementation of carbonatite and laumonite reduce the intergranular porosity,on the other hand, support the frame. and enhance the ability to resist compaction. Furthermore, it can provided space and material for the dissolution of secondary pores in the later. In addition, the dissolution changing the pore structure, making secondary pore development.