Permeability correction of tight shale reservoirs based on mercury intrusion capillary pressure: A case study from Erlian Basin

Reservoir permeability is a critical parameter governing shale-oil mobility. However, permeability values obtained by conventional methods are often overestimated due to fractures, leading to a poor relationship between permeability and pore–throat structure. This study presents an approach to correcting measured permeability by eliminating fracture-related effects. A suite of shale samples with varying lithologies from the Erlian Basin was collected, along with tight sandstones for comparative analysis. Helium porosity, permeability, and mercury intrusion capillary pressure (MICP) measurements were conducted to characterize the pore structure and transport properties. Results demonstrate that matrix permeability, estimated from MICP-derived mercury injection curves, is significantly lower than conventionally measured permeability. A strong correlation was observed between matrix permeability and average pore–throat radius, in contrast to the weak relationship shown by measured permeability. The corrected permeability, taken as the apparent permeability primarily related to pore–throat structures, was subsequently derived from the MICP-based matrix permeability. The corrected apparent permeability correlates well with average pore–throat diameter and porosity, especially in shale reservoirs. The findings provide a basis for refining reservoir classification criteria and offer insights into the spatial distribution of high-permeability zones. This work enhances the understanding of tight shale permeability and contributes to a more accurate assessment of shale-oil producibility.