Effective sand body distribution and its main controlling factors in tight sandstone gas reservoirs: A case study of southern Sulige Gas Field

The southern Sulige area is the southward extension of the main part of the Sulige Gas Field, where is far from sediment provenance, buried deep and has a strong diagenesis. Understanding the distribution characteristics and main controlling factors of effective sand body is the basis of the efficient development of the edge regions of the Sulige Gas Field, such as the southern Sulige area. Focusing on the reservoirs of He8 member and Shan1 member, the areas of tectonic, sedimentation, reservoir and diagenesis were studied, and the distribution characteristics and main controlling factors of effective sand body were concluded. The effective sand bodies in the southern Sulige area mainly distribute in point bars and the bottom of distributary channels, and can be vertically classified into three types: isolated, vertically stacking, and laterally shiplap ones. Horizontally, they locate in the central and eastern sand belts of the study area. During the formation of effective reservoirs, a gentle structure background is necessary for the sedimentation and formation of gas reservoirs. The shallow braided-river delta plain deposits in the strong hydrodynamic environment determined the distribution pattern of reservoir, whereas the compaction, cementation and dissolution diagenesis before the formation progress of gas reservoirs greatly reformed the reservoirs and controlled the distribution of effective sand body.