Experimental Characterization of Hydrodynamic Properties of a Deformable Rock Fracture

Abstract

Characterization of stress-dependent single-phase and multiphase fluid transport in fractured geo-materials is essential for a wide range of applications, including CO2 sequestration, energy storage, and geo-energy extraction. However, pivotal studies on capillarity and multiphase fluid flow in deformable rock fractures are surprisingly sparse. In this study, we initially investigated the hydro-mechanical properties of an intact mixed-wet Calumet carbonate from the Waterways formation (Alberta) under isothermal conditions (40 °C). Then, we conducted core-flooding experiments using water and N2 to assess changes in the aperture, absolute permeability, relative permeability, and capillary pressure of an artificially fractured Calumet core in response to changes in effective confining stress during loading (0–10 MPa) and unloading (10–3 MPa). We quantified the fracture’s non-linear closure and hysteresis effect during the cyclic loading–unloading processes. We found that porosity and absolute permeability of the fracture decreased from 1.5% and 19.8 D to 1.18% and 0.22 D, respectively, during the loading. We revealed a systematic rightward shift in the relative permeability and a significant upward shift in the dynamic capillary pressure curves as the fracture deformed. This fundamental study demonstrates the critical role of fracture deformation on fluid flow in fractured rocks, which paves the way for future research in geoscience and engineering.