致密砂岩微观孔隙非均质性定量表征及储层意义——以鄂尔多斯盆地X地区山西组为例

摘要

This paper presents a new method to extract the face rate of casting a thin section image of tight sandstones from the Shanxi Formation in the eastern Ordos Basin based on Matlab software programming.A heterogeneity coefficient U is proposed according to face rate, which quantitatively characterizes microscopic pore heterogeneity.The reser-voir significance of the heterogeneity coefficient U and the relationship between reservoir physical properties and microscopic pore heterogeneity were discussed.The results show that the micro-heterogeneity of the tight sandstone reservoirs in X area is very strong and the micro-pore distribution is very heterogeneous.A larger heterogeneity coefficient U and a stronger reservoir heterogeneity is associated with poorer reservoir physical properties, and vice versa.The microscopic heterogeneity of tight sandstone reservoirs influenced the microscopic development characteristics of pore space (reservoir space and permeability).The quantitative evaluation of the heterogeneity coefficient of tight sandstone reservoirs can guide the selection of high-quality strata for production.%以鄂尔多斯盆地东部X地区山西组致密砂岩储层为例,采用Matlab编程,提出铸体薄片图像面孔率提取的新方法,基于面孔率提出非均质系数U定量表征微观孔隙非均质性,并讨论非均质系数U和储层物性关系及微观孔隙非均质性的储层意义.结果表明,X地区致密砂岩储层微观非均质性强烈,微观孔隙分布十分不均匀;非均质系数U与孔隙度和渗透率均为负相关关系,非均质系数U越大,储层非均质性越强,储层物性越差,反之储层物性越好;致密砂岩储层微观非均质性控制着孔隙(储集空间和渗流空间)的微观发育特征,致密砂岩储层非均质系数定量评价有利于指导后期开发、开采中优质层位的圈定.