惠民凹陷商河油田商三区沙二下低渗透储层特征

The Low-Permeability Reservoir Properties of Lower Submember of Member 2 of Shahejie Formation in the Third Area of Shanghe Oilfield in Huimin Depression

摘要: 惠民凹陷商河油田商三区断块较多，沙河街组二段下亚段(Es^L₂)砂体形态复杂，属于低渗透储层，基础地质研究薄弱。以小层为研究单元，在开展沉积相精细研究的基础上，充分利用岩心、测井、录井、化验分析等资料，对Es^L₂储层的岩石学、孔隙结构、物性、非均质性、敏感性和裂缝等特征进行了详细研究及储层综合评价。研究表明，商三区Es^L₂属于中孔、低渗-特低渗储层；储层岩石类型以岩屑质石英粗粉-细砂岩为主，成分成熟度中等，结构成熟度较低；储集空间以粒间孔、粒间溶孔为主，孔喉半径较小；具有弱敏感性；层内和平面上具有较强的非均质性，层间非均质性较弱。以沉积微相分布和孔、渗数据为评价依据，对商三区Es^L₂储层进行分类和评价：I类储层物性最好，以河口砂坝为主；II类储层物性较好，主要以远砂坝为主，河口砂坝次之；III类储层物性最差，以发育支流间湾为主。其中I类和II类储层为主力层，主要分布在1 + 2砂组和3砂组。

Abstract: Because there existed many blocks in the 3^rd Area of Shanghe Oilfield, the shape of sand body was complex inEs^L₂. It belonged to a low permeability reservoir, where basic geologic study was less. By taking the sublayer as study unit, on the basis of the detailed study of sedimentary facies, fully applying the data of cores, well logging, geologic logs and chemical analysis, the reservoir characteristics of petrology, pore structures, physical property, heterogeneity, sensitivity and fractures in Es^L₂ were researched in detail, and then the reservoir was evaluated comprehensively. The study showed that the rock types were dominated by lithic quartz coarse siltstone-fine sandstone; its compositional maturity was medium and the textural maturity was low; the major types of pore were intergranular pore and intergranular dissolved pore; and the pore throat radius was small; the reservoir sensitivity was weak; inner layer and areal heterogeneity was stronger; and interlayer heterogeneity was weak. Based on the distribution of sedimentary microfacies and the data of the porosity and permeability, three types of reservoirs in the area were classified and evaluated. Physical property of Type I is the best, in which mouth bar is generally developed. Physical property of Type II is better than that of Type I, which is dominated by the distal bar and mouth bar is the next. Physical property of Type III is the poorest, which is dominated by the interbranch channel. The Type I and Type II are the major reservoirs among them, and they are mainly distributed in the sand group 1 + 2 and 3.