通过岩心观察、薄片鉴定、物性测试等技术方法,对东营凹陷南坡古近系沙河街组沙四上亚段滩坝砂岩储层特征、储层物性控制因素及有效储层成因进行研究.结果表明:储层主要为中、低孔储层;成岩作用类型多样,储集空间以原生孔隙为主,发育部分混合孔隙和次生孔隙;有利沉积条件是储层良好物性发育的基础,不同成岩作用类型及强度促使储层储集性能发生变化,油气充注、地层超压利于储层物性保存,其共同作用控制储层储集空间类型、分布组合及演化特征;有效储层其储集空间分布组合特征在纵向上具有分段性,1.0 ~2.0 km储层受成岩作用影响小,常压原生孔隙的良好保存形成以原生孔隙为主的有效储层,2.0~3.1 km储层溶蚀作用增加储集空间,地层超压、油气充注保存储集空间形成原生孔隙、混合孔隙、次生孔隙组合发育的有效储层,3.1~3.6 km储层油气充注、地层超压继承性发育,保存原有储集空间形成以原生孔隙为主、发育部分次生孔隙的有效储层.
This study focused on the beach-bar sandstone reservoir in the upper part of the fourth member of Shahejie formation in the southern slope of Dongying sag.Core,thin sections,physical properties and other technical methods were used to analyze the characteristics and genesis of effective reservoirs.The results show that the reservoir pore space includes mainly primary pores with partial secondary and mixed intergranular pores.Favorable sedimentary environment is the foundation of high-quality reservoirs.Different kinds of diagenesis and their intensity affect the quality of reservoir.Hydrocarbon charging and overpressure are the favorable preservation conditions of reservoir properties,and their interactions affect the types of reservoir space,the distribution and combination,and evolutional characteristics of reservoir.The distributions of pore space in effective reservoirs are sectionalized in depth.At 1.0-2.0 km,weak diagenesis and well preservation of primary porosity in ordinary pressure form effective reservoirs which contain mainly primary pores.At 2.0-3.1 km,dissolution increases reservoir space.Hydrocarbon charging and overpressure save reservoir space and form effective reservoirs which have primary pores,secondary pores and mixed pores.At 3.1-3.6 km,hydrocarbon charging and overpressure hold part of primary pores and form effective reservoirs which contain mainly primary pores and a few secondary ones.