丽水凹陷西凹中部储层致密成因及优质储层主控因素

Densification Causes and Main Controlling Factors of High Quality Reservoirs in the Central Section of Lishui West Sag

综合利用岩石薄片鉴定、扫描电镜、粉末粒度、物性、碳氧同位素分析等技术手段,结合物源、沉积微相对储层演化的耦合关系,在厘清储层基本特征基础上,分析了丽水凹陷西凹中部储层致密成因及优质储层主控因素。研究发现,丽水凹陷西凹中部储层石英含量低,酸性火成岩岩屑占60%,抗压实性能力较弱;储集空间中原生孔隙占90%,重力流为主的低位扇沉积砂体分选、磨圆较差,叠合高塑性组分的酸性火成岩岩屑母岩,导致丽水凹陷西凹中部储层易压实致密;西凹中部以原生孔为主导的优质储层受沉积微相控制,储层原始物性、沉积水动力、岩矿组分与储层质量密切相关,一般低位扇扇中微相的粗粒相带及高刚性颗粒含量砂体是优质储层的主要发育部位。

By means of the rock thin section identification,scanning electron microscope,powder size,physical property,carbon and oxygen isotope analysis,and in combination with the coupling relationship between the material source and the evolution of sedimentary microfacies to the reservoirs,the densification causes and the main controlling factors of high quality reservoirs in the central section of Lishui west sag were analyzed on the basis of clarifying the basic characteristics of the reservoirs.It is found that the quartz content of the reservoir in the central section of Lishui west sag is low,the acidic igneous rock cuttings account for 60%,and the compaction resistance is weak.In the reservoir space,the primary pores account for 90%;the lower fan sedimentary sand bodies dominated by gravity flow are poorly sorted and rounded;the acidic igneous lithic parent rocks superposed with highly plastic components lead to the easy compaction and densification of reservoirs in the central section of Lishui west sag.The high quality reservoirs dominated by primary pores in the central section of the western depression are controlled by sedimentary microfacies.The original physical properties,sedimentary hydrodynamics and rock-ore components of the reservoirs are closely related to the reservoir quality.Generally,the coarse grain facies zone and the sand body with high rigid particle content in the lower fan are the main developing parts of high quality reservoirs.