砂岩孔喉结构复杂性定量表征及其对渗透率的影响——以东营凹陷沙河街组为例

Quantitative characterization of complexity of sandstone pore-throat structure and its influence on permeability:A case study from Shahejie Formation of Dongying Sag

砂岩孔喉结构复杂性是影响其渗透率的重要因素,而渗透率是评价优质储层的重要参数,因此定量表征砂岩孔喉结构复杂性是砂岩储层质量分析的重要基础。为此,以东营凹陷沙河街组砂岩为例,基于薄片鉴定、粉晶XRD和MICP测试,引入孔喉体积分形维数、迂曲度和迂曲度分形维数对砂岩的孔喉结构进行定量描述,并探究其岩石学控制因素,系统地分析体积分形维数、迂曲度和迂曲度分形维数与渗透率之间的关系。结果表明:东营凹陷沙河街组砂岩孔喉结构复杂性及渗透率受沉积微相的影响较大。平均孔喉直径是控制孔喉结构复杂性的重要因素,孔喉结构复杂性(体积分形维数、迂曲度和迂曲度分形维数)是影响砂岩渗透率的关键因素。

As the complexity of sandstone pore-throat structure is an important factor affecting its permeability and the per⁃meability is crucial to evaluating high-quality reservoirs,it is vital to quantitatively characterize the complexity of sand⁃stone pore-throat structure.Therefore,this paper takes the sandstone of Shahejie Formation in Dongying Sag as an example.On the basis of the thin section identification,XRD,and MICP test,it introduces the pore throat volume fractal dimension,tortuosity,and tortuosity fractal dimension to quantitatively describe the pore throat structure of sandstone and explore their petrological factors.In addition,it systematically analyzes the relationship of volume fractal dimension,tortuosity,and tortu⁃osity fractal dimension with permeability.The results show that the complexity of pore throat structure and permeability of sandstone in Shahejie Formation of Dongying Sag are greatly affected by sedimentary microfacies.The average pore throat diameter is an important factor to control the complexity of pore throat structure,and the complexity of pore throat structure(the volume fractal dimension,the tortuosity,and the tortuosity fractal dimension)is a key factor affecting the permeability of sandstone.