Quantitative Characterization of Pore Connectivity and Movable Fluid Distribution of Tight Sandstones: A Case Study of the Upper Triassic Chang 7 Member, Yanchang Formation in Ordos Basin, China

摘要: The pore connectivity and distribution of moveable fluids, which determines fluid movability recoverable reserves, are critical for enhancing oil/gas recovery in tight sandstone reservoirs. In this paper, multiple techniques including high-pressure mercury intrusion porosimetry (MIP), nuclear magnetic resonance (NMR), scanning electron microscopy (SEM), microcomputer tomography (micro-CT) were used the quantitative characterization structure, connectivity, movable distribution. Firstly, sample porosity permeability obtained. Pore morphology 3D structures analyzed using SEM micro-CT, respectively. pore-size (PSD) from NMR was generally broader than that MIP because technique simply characterized connected volume, whereas showed total volume. Therefore, an attempt made to calculate percentages pores with different radii (  μm) contributed 5.02%–18.00% is less large contribution 36.60%–92.00%, although small had greater volumes. addition, a new parameter, effective saturation, proposed based on initial saturation percentage NMR. results demonstrated decreased by 14.16% average when disconnected excluded. It concluded has higher accuracy evaluating