饶阳凹陷中深层碳酸盐胶结物特征及其对储层孔隙特征的影响

Characteristics of the carbonate cements and their influences on the reservoir pore properties in the middle and deep layers of Raoyang Sag

饶阳凹陷中深层储集层中碳酸盐胶结物含量高,其类型和分布极大影响储层孔隙特征。为明确下一步勘探开发方向,利用岩心、薄片、电镜、阴极发光、碳氧同位素等资料对研究区碳酸盐胶结物类型、成因、分布规律进行研究。认为研究区碳酸盐胶结物成分主要为方解石和白云石,铁方解石、铁白云石少量,存在3期碳酸盐胶结物,不同期次胶结物的类型、成因不同。平面上,不同区域胶结物成分和含量差异性明显,席状砂微相是碳酸盐胶结物有利发育区,纵向上主要分布在砂泥接触的顶底面附近,距离接触面越近,胶结物含量越高。碳酸盐胶结物影响储层孔隙特征,胶结物含量越高,孔隙结构越差,碳酸盐胶结物控制储层类型,与孔隙度和渗透率负相关,对储层物性的影响具有双重性,早成岩期胶结物对储层物性起建设作用,中成岩期胶结物对储层物性起破坏作用。

The contents of the carbonate cement are rather higher in the middle and deep layers of Raoyangg Sag, the cement types and distribution seriously affect the reservoir pore characteristics. In order to make certain of the further exploration and development directions, the core, thin section, scanning electron microscopy, canthodoluminescence, carbon-oxygen isotope data are integrated to study the carbonate cement type, origin and distribution law. The results show that the types of the carbonate cement are mainly calcite and dolomite, the ferrocalcite and ferrodolomite is minor, there are three periods of the carbonate cements in the study area, the type and genesis of the carbonate cements at different periods and times are different. The composition and content of the carbonate cements in different regions are quite various on the plane, the sheet sand microfacies is the favorable well-developed area of the cements;the carbonate cements are mainly distributed around the top and bottom surface of the sand-mud contact in the vertical direction, the more closed to the contact surface, the higher content of the carbonate cements will be. The carbonate cements influence the reservoir pore characteristics, the higher content of the carbonate cements is, the worse the pore structure will be, the carbonate cements control the reservoir types and moreover are negatively correlated with the porosity and permeability, so the effects of the carbonate cements on the reservoir physical property are dual, the cements in the early diagenetic stage play constructive action to the reservoir physical property, while the cements in the middle diagenetic stage play a destructive role to the reservoir physical properties.