基于压汞实验的致密砂岩储层物性响应及分形特征

Physical Response and Fractal Characteristics of Tight Sandstone Reservoir Based on Mercury Injection Experiment

论文为探究鄂尔多斯盆地G井区盒8段储层特征及影响储层微观孔喉复杂程度的因素。通过铸体薄片、扫描电镜、X全岩衍射实验和高压压汞等实验及分形理论,分析储层特征,并通过储层物性、孔喉特征参数及矿物成分等因素,探究各因素与孔喉复杂程度的关系。研究表明:研究区盒8段储层岩性为灰白色中—细砂岩,储集空间以粒间孔、溶蚀孔为主,喉道类型有缩颈、片状和弯片状喉道,为特低孔—超低孔的致密砂岩储层;储层分形维数多数大于2.5,非均质性较高,分形维数随储层物性变差而增大;分形维数与孔喉特征参数有较好的相关关系,孔喉特征对储层的储集性能和渗流能力有一定影响;分形维数与部分矿物之间具有相关性,矿物成分及其含量是决定孔喉复杂程度的内在因素,影响着储层的质量和物性特征。

In order to explore the reservoir characteristics of He 8 of G Well block in Ordos Basin and the factors affecting the complexity of microscopic pore-throat.Reservoir characteristics were analyzed by casting thin section,scanning electron microscope,X-whole rock diffraction experiment and high-pressure mercury injection,and the relationship between various factors and pore-throat complexity was explored through reservoir physical properties,pore-throat characteristic parameters and mineral composition.The results show that the reservoir lithology of He-8 member in the study area is gray-white medium-fine sandstone,and the reservoir space is mainly intergranular pores and dissolution pores.The throat types are neck-constricted,flaky and bent flaky,and it is a tight sandstone reservoir with ultra-low porosity and ultra-low porosity.The fractal dimension of most reservoirs is greater than 2.5,and the heterogeneity is high.The fractal dimension increases with the deterioration of reservoir physical properties.There is a good correlation between fractal dimension and pore-throat characteristic parameters.Pore-throat characteristics have a certain influence on reservoir performance and seepage capacity.The fractal dimension is correlated with some minerals,and the mineral composition and content are internal factors that determine the complexity of pore-throat,and affect the reservoir quality and physical characteristics.