Numerical computations of rock dissolution and geomechanical effects for CO₂ geological storage

Abstract

SUMMARYThe paper is motivated by the long-term safety analysis of the CO 2 geological storage. We present a methodology for the assessment of the geomechanical impact of progressive rock dissolution. The method is based on the use of X-ray tomography and the numerical dissolution technique. The influence of evolution of the microstructure on the macroscopic properties of the rock is analysed by using periodic homogenization method. The numerical computations show progressive degradation of all components of the stiffness (orthotropic) tensor. Moreover, the evolution of associated mass transfer properties (as tortuosity and conductivity tensors), by using the periodic homogenization method, is also calculated. The correlation between the mechanical parameters and the transfer properties during the dissolution process is presented. The results show that the highest increase of the hydraulic conductivity (in direction Y ) is not associated with the highest decrease of Young modulus in this direction. Moreover, the highest decrease of Young modulus (in the direction X ) is not associated with percolation in this direction. Finally, an incremental law to calculate settlement, in case of a rock with evolving microstructure, is proposed. The solution of the macroscopic settlement problem under constant stress and drained conditions showed that the geomechanical effects of the rock dissolution are rather limited.

Quantifying Rock Weakening Due to Decreasing Calcite Mineral Content by Numerical Simulations

“…This workflow improves the processing efficiency and results in substantially lower computational times, which is especially relevant for multi-million voxel micro-CT scans. Microstructures are often divided into regular adjacent cubes, which are separated [ 53 ] or overlapping each other [ 55 ], but also non-neighbouring sub-volumes or a random selection can be employed for that purpose [ 75 , 76 ]. In our approach, the Fontainebleau sandstone is randomly decomposed into 30 sub-cubes of 100 3 voxels each, with an allowed overlap of 34% in maximum.…”

Computing the elastic properties of sandstone submitted to progressive dissolution

“…Phenomenological model were also proposed by Coussy [13] in which variations of poroelastic parameters are described as a heuristic function of irreversible porosity caused by chemical degradation. Numerical and computational aspects of chemo-mechanical modelling related to flow and transport phenomena during injection process are presented by Doughty et al [14], Kumar et al [15], Hovorka et al [16] and Wojtacki et al [17].…”

A two‐invariant pseudoelastic model for reservoir compaction

“…[1][2][3][4][5][6] Ground motions can be the consequence of several anthropogenic activities, involving the underground withdrawal and injection of fluids. Some examples are the extraction of hydrocarbons from deep reservoirs, 7-9 the injection of steam/CO 2 to enhance oil recovery, 10 the sequestration of CO 2 in geological formations to reduce the greenhouse gas emissions in the atmosphere, [11][12][13][14] and the gas storage in depleted gas fields to ensure strategic supply in high-demand periods. 15 The reliable prediction of reservoir deformations, due to the aforementioned activities, is essential to avoid structural damages to the well casings, 16 safety problems on offshore platforms, and social and environmental concerns due to land subsidence and differential displacements.…”