Study On Sedimentary And Reservoir Characteristics Of Chang6 Formation In Xunyi Exploration Area

XunYi exploration area is located in the edge of Ordos basin. There are significant differences about the oiliness of Chang 6, the exploration target strata. The research of oil and gas distribution regularity is weak. It affects the future of exploration deployment in this region. Through the analysis the regional geology of the basin, using the drilling core observation, logging data analysis, the rock slice, the mercury injection,, scanning electron microscopy, and so on, the sedimentary microfacies of the main oil reservoir of Mesozoic formation in the studied area is divided, and the sedimentary microfacies map is compiled, analyzed the sedimentary microfacies relative to the influence of reservoir characteristics.Studies have shown that Yan Chang formation of XunYi exploration area is in the delta front part, the main types of sedimentary facies are delta front subfacies of underwater distributary channel, distributary bay deposit, estuary sand bars, underwater natural levee, crevasse splay, etc. From west to east there are two or three north-east distribution, throughout the whole are composite underwater distributary channels, and the inheritance is stronger. The Chang 6 is low porosity and low permeability reservoir. In vertical, porosity and permeability in the reservoir has the heterogeneity between groups. Clastic composition, cement composition and content in the reservoir are the main factors affecting reservoir physical properties. With the increase of the content of quartz, the reservoir property is slightly better. The porosity with the increase of the feldspar content is slightly worse. According to the capillary pressure curve morphological characteristics and parameters analysis, the sandstone reservoir of Yan Chang formation of XunYi exploration area is divided into Ⅰ, Ⅱ, Ⅲ, Ⅳ etc. All four types exists in the each reservoir group. I class reservoir exists in the main channel, Ⅱ, Ⅲ class reservoir mainly distribute in the flank of the channel, Ⅳ class main developments between distributary bay reservoir.The sedimentary systems, reservoir characteristics, favorable exploration area and reservoir distribution of Chang6 Formation of Xunyi exploration area was determined, all these ensured the rational and efficient development and stimulate of oil and gas resources in this area. Meanwhile, we can continue to expand eastward and westward base on this district, gradually increase exploration degree of neighbor district. It can be the foundation of overall effective deployment of the South Districts and follow-up exploration planing.