致密砂岩气藏有效砂体分布及主控因素——以苏里格气田南区为例

苏里格气田南区是苏里格气田主体向南的延伸,距离物源区远,储层埋深大,成岩作用强。落实有效砂体分布及主控因素,是苏南等气田边部地区高效开发的基础。以苏南盒8、山1段储层为目标,结合构造、沉积、储层、成岩分析,研究了有效砂体的空间展布特征,总结了有效砂体的主控因素。苏南有效砂体多分布在心滩和分流河道底部等粗砂岩相,垂向上发育孤立型、垂向叠置型、侧向搭接型3种模式,平面上分布在中、东部2条主砂带内。在有效储层形成过程中,宽缓的构造坡降是沉积、成藏的背景,强水动力条件下的浅水辫状河三角洲平原沉积控制了储层的分布格局,而成藏前的压实、胶结、溶蚀等成岩作用深刻改造了储层,塑造了有效砂体的形态。

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.