微孔喉对基质-裂缝介质储渗特征的影响规律研究

Effect of Micro Pore-throat on Porosity and Permeability of Dual Media Digital Rock

选取代表性的砂岩基质样品和裂缝样品,通过微米CT扫描方法分别建立相应的基质和裂缝三维数字岩心。然后,基于相同物理尺寸和分辨率的基质样品数字岩心和裂缝数字岩心,通过布尔叠加算法构建基质-裂缝双重介质数字岩心;同时,基于图像开运算算法进行孔隙体素消除,获取不同微孔喉尺寸的基质数字岩心,并叠加构建不同微孔喉尺寸的基质-裂缝双重数字岩心。最后,基于不同微孔喉尺寸下基质样品和基质-裂缝双重介质样品三维数字岩心,分别计算相应的总孔隙度、连通孔隙度和绝对渗透率,可以发现:微孔喉对基质和基质-裂缝样品的总孔隙度整体贡献较小;微孔喉对基质的连通孔隙度有较大贡献,但对双重介质的连通孔隙度贡献较小;微孔喉对基质的渗透率有重要贡献,对基质-裂缝双重介质的渗透率贡献较小。

In this paper,the representative sandstone matrix and fracture sample are selected for CT scanning to build the corresponding matrix and fracture digital rock respectively.Then,based on the matrix and fracture digital rock with the same physical size and resolution,the Boolean superposition algorithm is introduced to construct matrix-fracture dual media digital rock;meanwhile,an image opening algorithm is used to eliminate pore voxel,and matrix digital rock with different micropore size is reconstructed,also,the superposition algorithm is conducted to reconstruct matrix-fracture dual digital rock with different micropore sizes.Finally,based on the matrix digital rock and matrix-fracture digital rock with different micropore sizs,the total porosity,connected porosity and absolute permeability are calculated.It can be found that,the micro pore-throat has lower contribution to the total porosity of matrix and dual media;the micropore-throat contributes more to the connected porosity of the matrix,but less to the connected porosity of dual media;the micropore-throat makes important contribution to the permeability of matrix,but less to the permeability of dual media.This paper provides an important platform to study the porosity and permeability characteristics of matrix-fracture dual media,which is of great significance to the development of dual-media reservoirs.