鄂尔多斯盆地东缘上古生界沉积特征研究

Study on sedimentary characteristics of Upper Paleozoic in the eastern margin of Ordos Basin

通过对鄂尔多斯盆地东缘上古生界野外露头特征、颜色特征、岩性及沉积构造特征等相标志的详细分析,确定了研究区上古生界发育2种沉积相模式,进一步划分5种亚相及8种微相类型。本溪-太原组沉积时发育海相障壁海岸-潮坪沉积体系模式,储集砂体主要为潮道、砂坪、障壁砂坝微相;山西-石盒子-石千峰组沉积时,沉积环境过渡到广泛的陆相河流-浅水三角洲沉积体系,储集砂体主要为分流河道、(水下)分流河道及河口坝微相。高能沉积微相形成的储层具有“相对高孔渗”储层物性,孔隙结构好,为有效储层发育区,钻遇气层占比大。

Through the detailed analysis of the field outcrop characteristics,color characteristics,lithology and sedimentary structure characteristics of Upper Paleozoic in the eastern margin of Ordos Basin,two sedimentary facies models are determined,and further divided into 5 subfacies and 8 microfacies.During the deposition of Benxi–Taiyuan Formation,a marine barrier coast tidal flat sedimentary system model was developed.The reservoir sand bodies are mainly tidal channel,sand flat and barrier bar microfacies.During the deposition of Shanxi-Shihezi-Shiqianfeng Formation,the sedimentary environment transited to a wide range of continental river shallow water delta sedimentary system.The reservoir sand bodies are mainly distributary channel,(underwater)distributary channel and estuary bar microfacies.The reservoir formed by high-energy sedimentary microfacies has"relatively high porosity and permeability"reservoir physical properties and good pore structure.It is an effective reservoir development area with a large proportion of drilled gas reservoirs.