西湖凹陷深层致密砂岩裂缝控制因素及发育模式OA北大核心CSTPCD

Most of the oil and gas resources in the Xihu Sag are concentrated in deep low-porosity and permeabil-ity reservoirs below 3 500 m.Previous studies on deep fractured"sweet spot"reservoirs in this area are relatively rare.Taking the W structure in the central depression belt as the research target area,the fracture prediction meth-od is summarized,and the controlling factors and development patterns of deep fracture formation are studied.Results show that the fractures in the deep tight sandstone reservoir of the W structure could be classified into dia-genetic fractures,shear fractures,and tension fractures in fracture genesis type.Among them,the diagenetic frac-tures is controlled by sedimentary bedding and pressure release.The shear fractures are controlled by the intensity of stratum deformation and are mainly developed in the parts with strong deformation of the Huagang Formation.The tension fractures are related to the horizontal extension stress generated after the stratum uplift.After analyz-ing the reservoir physical properties,we believe that the development of deep fractures is one of the important factors controlling the"sweet spot"reservoirs of tight sandstone gas reservoirs.Through tectonic stress field simu-lation combined with single well core and thin section analysis,the concentrated development area of fractures can be effectively predicted,providing a basis for the prediction of deep fractured"sweet spot"reservoirs.