渤中凹陷石南斜坡区古近系中深层优质储层形成机理

Formation mechanism of Paleogene high-quality reservoir in mid-deep strata in Shinan slope of Bozhong Depression

运用普通薄片、铸体薄片、扫描电镜、阴极发光、包裹体、X衍射和物性分析等手段,对渤中凹陷石南斜坡区古近系中深层储层特征及形成机理进行研究。结果表明,研究区古近系中深层存在优质储层,孔隙度为20%左右,渗透率为(100～1 000)×10-3μm2,为高孔高渗储层。储层孔隙类型以粒内溶孔、粒间溶孔和残余原生粒间孔为主,次生孔隙较原生孔隙发育。沉积作用为研究区中深层优质储层的形成提供了前提和基础,溶蚀作用是形成该优质储层的直接原因,成岩演化控制了区内古近系中深层储层中3个次生孔隙发育带。异常高压和烃类早期充注是形成中深层优质储层的辅助因素。

In this paper, the reservoir characteristics and formation mechanism of Paleogene mid-depth high-quality reservoir are studied in Shinan slope of Bozhong Depression through the analysis of ordinary thin section, cast thin section, scanning electron microscope, cathodeluminescence, inclosure, X-diffraction and physical properties. The results show that the high-quality reservoir exists in Paleogene mid-depth reservoir. With the porosity of 20% and the permeability of 100-1,000 md, the reservoirs are classified as high porosity and high permeability reservoirs. The pore types of reservoir are mainly intragranular dissolved pore, intergranular dissolved pore and residual primary intergranular pore. The development of secondary pore is better than primary pore. Sedimentation provides the premise and basis for the formation of Paleogene mid-depth high-quality reservoir in the study area. Denudation is the direct reason of the formation of high-quality reservoir. Diagenesis evolution controls the three development zones of secondary pore in Paleogene mid-depth reservoir. The existence of abnormal pressure and early hydrocarbon filling is the auxiliary factor of the formation of mid-depth high-quality reservoir.