3D Simulations of gas injection on callovo-oxfordian claystone assuming spatial heterogeneity and anisotropy. (November 2022)

• Record Type: Journal Article
• Authors: Damians, I.P.; Olivella, S.; Gens, A.
• Is Part Of: International journal of rock mechanics and mining sciences. Volume 159(2022)
• Publication Date: 2022-11
• Subjects: Hydro-gas-mechanical 3D model -- Gas flow -- Embedded fracture model -- Material heterogeneity -- Anisotropy; Rock mechanics -- Periodicals; Soil mechanics -- Periodicals; Mining engineering -- Periodicals; Roches, Mécanique des -- Périodiques; Sols, Mécanique des -- Périodiques; Technique minière -- Périodiques; 624.151305
• DOI: 10.1016/j.ijrmms.2022.105232
• Languages: English
• ISSNs: 1365-1609

Abstract

Abstract: A series of gas injection tests on Callovo-Oxfordian (COx) claystone from the Bure underground research laboratory (URL) in France were carried out at the British Geological Survey (BGS). The tests were performed using a triaxial apparatus specifically designed to capture small volumetric strains induced by the injected gas flow and consequent material dilatancy. The long-duration experiments were monitored throughout. Measurements also included pressure, stresses (axial and radial stresses prescribed for each test stage), rate of gas inflow, gas outflow volume as well as pore-pressures observed at various points of the sample. A coupled hydro-gas-mechanical 3D numerical model has been developed to simulate the tests. Initial permeability is assumed heterogeneous throughout the specimen and embedded fractures are incorporated in the formulation. Gas pressure-induced deformations during the test lead to variations of permeability due to changes in matrix porosity and, especially, fracture aperture as well as fracture orientation due to material anisotropy. A programme of sensitivity analyses involving the variation of different aspects and parameters of the model contributes to a better understanding of the phenomena and highlights its complexity. The model is able to reproduce the observed behaviour of the tests.