苏里格气田S区块山西组山1段沉积微相特征研究

Study on Sedimentary Microfacies Characteristics of Shan-1 Member of Shanxi Formation,Block S,Sulige Gas Field

上古生界山西组山1段为鄂尔多斯盆地苏里格气田S区块的主力产气层,厘清其沉积相特征,对指导该地区的天然气勘探具有一定意义。运用沉积学基础原理和方法,综合岩心观察、测井曲线、微量元素特征、沉积构造及古生物化石等资料,对苏里格气田S区块山1段进行系统研究。并结合单井相、沉积相连井剖面及砂地比特征,刻画山1段沉积微相展布特征。研究结果表明,研究区岩性主要为中-细砂岩,总体表现出牵引流的沉积特征,沉积环境为气候较湿润的弱还原-还原的水下沉积环境。岩心上见冲刷面、板状交错层理、平行层理和水平层理等沉积构造,古生物化石以碳化植物茎杆化石或植物叶片化石印模为主。山1段为曲流河三角洲前缘沉积,划分为水下分流河道、水下分流间湾、席状砂沉积微相,主要发育近北南向的水下分流河道砂体,为研究区最主要的储集体。

The Shan 1 Member of the Shanxi Formation in the Upper Paleozoic is the major gas-producing layer in Block S of the Sulige Gas Field in the Ordos Basin.Clarifying its sedimentary facies characteristics is of certain significance for guiding natural gas exploration in the area.Using the basic principles and meth-ods of sedimentology,a systematic study is done on the Shan 1 Member of Block S in the Sulige Gas Field based on integrating core observations,well logging curves,trace element characteristics,sedimentary structures,paleontological fossils,and other data.Combined with the well profiles of single well facies and sedimentary fa-cies,and sandstone-formation thickness ratio characteristics,the sedimentary microfacies distribution characteristics of the Shan 1 Member are described.Research results show that the lithology of the study area is mainly medium-fine sandstones,which generally show the depositional characteristics of traction current,and the deposition environment is a weak reduction-reduction underwater one with a humid climate.Sedimentary structures such as erosion surfaces,tabular cross-bedding,parallel bedding,and horizontal bedding can be seen on the cores.The paleontological fossils are mainly carbonized plant stem fossils or plant leaf fossil impressions.In the Shan 1 Member,the meandering river delta front was deposited,which is divided into underwater distributary channels,underwater distributary bays,and sheet sand sedimentary microfacies.Underwater distributary channel sand bodies nearly in the north-south direction developed mainly,which is the main reservoir in the study area.