Classifying Multiscale Pores and Investigating Their Relationship with Porosity and Permeability in Tight Sandstone Gas Reservoirs

Since tight sandstone usually contains pores of multiscales and various types, it is important to classify pores in scale and investigate their distinct contributions to porosity and permeability for better understanding of the storage and percolation mechanism of tight gas sandstone reservoirs. In this study, rate-controlled porosimetry (RCP) was performed to probe the pore connectivity and fractal structures and classify pores’ size, while low temperature N2 adsorption and nuclear magnetic resonance (NMR) were conducted to determine the specific surface area (SSA) and the relative content for different scales of pores, respectively. Based on the differences in pore connectivity and the contributions to storage and percolation, pores in tight sandstone are divided into nanopores (mainly 1.5 μm). Nanopores consist of the clay-associated pores and intraparticle dissolution pores, contributing to both percolation and storage, especially to t...