鄂尔多斯盆地苏里格气田苏6区块盒8段密集井网区古河道砂体定量化表征

Quantitative characterization of paleochannel sandbody evolution in dense well net area of He 8^th layer of Su 6 block in the Sulige gasfield,Ordos basin

为了探究鄂尔多斯盆地苏里格大气田苏6区块盒8段(H8)主力产气层的沉积特征和砂体演化规律,通过详细的岩心描述、岩相类型及岩相组合特征分析等方法,认为研究区目的层为河流相沉积,盒8下段(H8X)为辫状河沉积,发育河道底床、心坝、沙坪和沙泥坪微相;盒8上段(H8S)发育曲流河沉积,主要有河道滞留沉积、点坝、河漫滩微相,岩性以中细砂岩为主。在现代河流参数测量分析的基础上,通过选取密集井网区连井剖面,对河相河道构型要素规模进行解剖,得出曲流河的河道带度约为1350 m,点坝微相长度范围为500~1700 m,宽度范围为200~800 m;辫状河的河道带宽度约为1920 m,心坝长度范围为500~1600 m、宽度范围为250~1000 m。该研究结果为砂体精细刻画提供了数据支撑,可有效指导井网加密和开发方案的调整。

The He 8^th layer(H8)of Su 6 block in the Sulige gasfield,Ordos basin is the main gas producing layer in the gas field.However,its sedimentary characteristics and sand body evolution are extremely complex.It is considered that the target layer in the study area is fluvial deposits based on detailed core description,lithology,sedimentary structure and cycle characteristics analysis.The lower part of the He 8^th layer(H8X)deposits braided river,which develops channel bedform,channel bar,sand flat and sand-mud flat microfacies;The upper part of the He 8^th layer(H8S)deposits meandering river system,which develops bed residence,point bar,floodplain and overbank microfacies,and the lithology is dominated by fine to medium sandstone.It is concluded that the channel belt degree of meandering river is about 1350 meters,the length and width of point bar are 500-1700 meters and 200-800 meters respectively;the river belt width of the braided river is about 1920 meters,and the length and width of the channel bar are 500-1600 meters and 250-1000 meters respectively by choosing the well-tie sections of dense well pattern area.The research results provide data support for fine sand body characterization,and can effectively guide well pattern infilling and development program adjustment.