致密砂岩气储层有效性识别和定量评价——以鄂尔多斯盆地东南部上古生界山西组一段为例

Availability Identification of Tight Gas Sandstone Reservoirs and Quantitative Assessment:A case study from the first member of the Upper Paleozoic Shanxi Formation in the southeastern Ordos Basin

储层有效性识别和定量评价是制约致密砂岩油气勘探的关键难题。以鄂尔多斯盆地东南部上古生界山西组一段为研究对象,从储层非均质性研究入手,开展砂岩微观—岩芯—测井尺度的细致观测,将含气储层砂岩划分为三种主要的岩石相,其中贫塑性颗粒岩屑石英砂岩构成了物性和含气性相对较好的有效储集岩石。运用薄片和岩芯数据标定不同岩石相的常规测井响应,建立了基于主成分统计分析的有效储集岩石测井识别模型,认识了有效储层的空间分布规律。将储层有效性研究从微观尺度的岩石相描述拓展到宏观尺度的量化表征,实现了致密砂岩气有效储集空间分布的定量评价。

Identification of reservoir availability and quantitative assessment are some of the most critical issues in tight sand oil and gas exploration. Multiple analysis scales from the microscale, drill core to well logging have been conducted to examine the reservoir heterogeneity of the first member of the Upper Paleozoic Shanxi Formation in the southeastern Ordos Basin. Three sandstone petrofacies have been defined in the gas reservoirs. Ductile grain-lean sublitharenite forms reservoir rocks with good petrophysics and gas show. A model based on principal component analysis has been constructed to predict high-quality reservoir rocks and understand their spatial distribution patterns using well logs corrected from thin section and drill core data. The micro-scale description of the petrofaceis has been upscaled for field-scale characterization, and the availability of tight gas sandstone reservoir has been quantitatively assessed.