苏里格气田密井网区辫状河心滩刻画

Characterization of Braided River Channel Bar in Dense Well Pattern Area of Sulige Gasfield

心滩是辫状河的骨架砂体,是苏里格气田的主要成藏单元。为了在砂体中准确识别心滩,判断心滩的发育规模及影响因素,以苏里格气田苏X加密区块为例,在明确沉积类型及地层精细划分的基础上,利用河道砂厚中心连线法、单一河道分界标志、心滩测井相分异法,借鉴国内外学者对典型河流沉积的研究成果,解剖与研究区沉积环境相似的现代沉积和野外露头,对钻遇心滩进行识别,对未知心滩进行预测,最终完成整个研究区心滩的刻画。结果表明:研究区心滩在平面上可以分为头部、尾部、翼部、核部4部分。判定研究区心滩的长宽比约1.3∶1~1.6∶1,心滩长厚比约80∶1~135∶1,宽厚比约60∶1~85∶1,心滩长度为300~700 m,宽度为240~450 m。在心滩形成演化过程中,心滩发育的规模可能受河道的弯度指数控制,河道弯度指数越大,心滩的规模越小。

Channel bar is the skeleton sand body of braided river and the main reservoir forming unit of Sulige Gasfield.In order to accurately identify channel bar in the sand body,judge the development scale and influencing factorsof channel bar,taking Su X dense well pattern block in Sulige Gasfield as an example,on the basis of determining sedimentary type and fine stratigraphic division,the drilled found channel bar is identified,the unknown channel bar is predicted,and finally the characterization of the channel bar in the whole study area is completedby means of the channel sandbody thickness center connectingmethod,single channel sandbody boundary markers and channel bar logging facies differentiation method,the research results of scholars at home and abroad on typical fluvial facies and the analysis of modern sedimentation and field outcrops similar to the sedimentary environment in the study area.The results show that the channel bar in the study area can be divided into four parts on the plane:head,tail,wing and nucleus.The length-width ratio of channel bar in the study area is about 1.3∶1~1.6∶1,the length-thickness ratio of channel bar is about 80∶1~135∶1,the width-thickness ratio is about 60∶1~85∶1,and the length and width of channel bar are 300~700 m and 240~450 m respectively.In the formation and evolution process of the channel bar,thedevelopment scale of channel bar may be controlled by the channel curvature index.The greater the channel curvature index,the smaller the development scale of the channel bar.