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通过铸体薄片显微镜下观察、孔喉图像、毛细管压力、恒速压汞、气水相对渗透率、核磁共振等多种分析实验手段,研究了鄂尔多斯盆地东部上古生界盒8段低孔、低渗-特低渗砂岩储层的微观孔隙结构和渗流特征,探讨了孔隙结构对储层渗流特征的影响。结果表明,孔隙结构特征是影响低孔、低渗-特低渗砂岩储集性能与渗流特征的主要因素。而砂岩的孔隙结构特征主要受砂岩原生矿物组合与成岩演化过程及其产物的控制,盒8段各砂岩类型由于其矿物成分不同导致孔隙结构的差异,也是各砂岩类型储集性能与渗流能力存在差别的直接原因。在孔隙结构参数中,喉道的大小、有效孔隙与喉道的体积及其连通性是决定储层储集与渗流能力的关键。大孔喉对储层渗流能力的贡献更大,中-小孔喉则对储集能力的贡献相对较高。微裂缝是除孔隙结构以外影响砂岩储集性能与渗流特征的重要因素。
Through the observation of cast thin slice microscopy, pore-throat image, capillary pressure, constant pressure mercury injection, gas-water relative permeability and nuclear magnetic resonance and other analytical methods, the effects of low porosity and low porosity in the upper Paleozoic Eighth Member of the Ordos Basin The microscopic pore structure and seepage characteristics of seepage-infiltration-ultra-low permeability sandstone reservoirs, and discusses the influence of pore structure on reservoir seepage characteristics. The results show that the pore structure characteristics are the main factors affecting the reservoir performance and seepage characteristics of low porosity and low permeability - ultra low permeability sandstone. The pore structure of sandstone is mainly controlled by the primary sandstone assemblage and diagenesis evolution and its product control. The sandstone types in Box 8 are different in pore structure due to their different mineral compositions, and also exist in the reservoir performance and seepage capacity of each sandstone type The direct reason for the difference. In pore structure parameters, the size of the throat, the effective pore space and throat volume, and their connectivity are the keys to determining the reservoir’s ability to reservoir and seepage. Macropores contribute more to the seepage capacity of reservoirs while medium-small pore throats contribute more to reservoir capacity. Microfissure is an important factor that affects the reservoir performance and seepage characteristics of sandstone except for the pore structure.