InterPore2025

An integrated approach to correction for high pressure mercury intrusion experiment of shale cores based on Micro CT and FE-SEM imaging

22 May 2025, 14:45

15m

Oral Presentation (MS17) Complex fluid and Fluid-Solid-Thermal coupled process in porous media: Modeling and Experiment MS17

Speaker

Dr Yan Wang (State Key Laboratory of Continental Shale Oil, China; Exploration and Development Research Institute of Daqing Oilfield Co Ltd, China; Heilongjiang Provincial Key Laboratory of Reservoir Physics & Fluid Mechanics in Porous Medium, China)

Description

Mercury intrusion porosimetry（MIP）is a common but indirect technique for characterizing and analyzing pore structures. It provides pore/throat size distribution and capillary breakthrough pressure by measuring the injected mercury volume along with increasing injection pressures. However, our Micro-CT comparison results substantiated that MIP results deviate from real pore structure characterization by reason of incomplete mercury intrusion, which is mainly due to microscopic heterogeneity and fracture compressibility of pore spaces in shale cores. Particularly, random micro- and nano-cracks, which could manifest as continuous accumulation space and inhomogeneous, distorted, compressible stress field, are major contributors to data deviation. The complex mineral composition and uncertain connectivity of nanopores also affect the accuracy of capillary breakthrough pressure in MIP results under high-stress conditions. The stress deformation of pore structure of three typical types of Gulong shale cores are studied by using Wood’s metal injection at 30MPa, 50MPa and 200MPa respectively. Micro-CT and FE-SEM images of core samples before and after injection were compared to evaluate Wood’s metal intrusion in pore/crack structures at micrometer and nanometer scales. Through the estimation and analysis of the Wood’s metal filling amount in cracks and intrusion distance in the matrix under three different pressure conditions, the post-stress deformation and excess cumulative injected volume are calculated. Applying this calculation of stress deformation and excess volume, this paper presents a method for modifying high pressure mercury porosimetry results based on the crack initiation and cumulative injection volume correction. By comparing the pore size analysis results obtained by the nitrogen adsorption method, we verify the feasibility of the proposed method and the reliability of the improved analytic results.