v5.0.0

Zhang, Q., Yin, Z.-Y., Yan, X., 2024. Anisotropic continuum framework of coupled gas flow - adsorption - deformation in sedimentary rocks. Int. J. Numer. Anal. Methods Geomech. 48, 1018–1045. https://doi.org/10.1002/nag.3674

Zhang, Q., Yin, Z.-Y., Yan, X., 2023. Material Constants of Anisotropic Poroelasticity and Its Impacts on Shale Gas Production. Energy Fuels 37, 17617–19376. https://doi.org/10.1021/acs.energyfuels.3c02656

Simulation code and supplementary file for CMAME paper: A novel stabilized NS-FEM formulation for anisotropic double porosity media

You can run the following files directly: main_1d_DPSK.m, Vertical_cut.m, and ./AMCC_shale_example/Dcon2_specimenBVP.m.

ProposedGeneralizedEqs_preprocessOFsec2.m is the implementation of our proposed phenomenological approach. The attached xlsx file is the implementation of the mixture theory.

In the folder ./reference_1D_consolidation, there are two .mat files that save the numerical results, and the remaining codes implement the analytical method (Laplace transform and numerical inversion). Two cases correspond to different $K_f$ and leakage parameter $\gamma$.

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Standard MCC "Fluid-Solid Coupled" code

A standard 2D consolidation example is used to illustrate this code (bulk modulus K is solid pressure dependent), see Dcon2_gfooting_MCC.m file. The COMSOL file is used to verify the MATLAB code during the preloading stage. The COMSOL failed to converge during the second stage.

The second .m file Dcon2_MCC_gravity_initialOCR.m generates the initial OCR profile as suggested in Borja and Lee (1990). The result is shown below, in which the color bar is not scaled.

Another one for double porosity and advanced solid model

This release is actually a zip file that contains the numerical scheme for a coupled double porosity hydromechanical model. The anisotropic modified Cam-Clay model is adopted to simulate the behavior of solid (shale-like material). It differs from the original MCC model even in the isotropic case. Both the solid anisotropy and permeability anisotropy are affected by the orientation theta (counterclockwise is positive), whose default value is 45 [deg]. If you want to change theta, you only need to change it at the beginning.

There are two main simulation files. The second file approximately simulates the example from Zhao and Borja (2021), since we DO NOT handle a finite Ks (solid grain bulk modulus) case. In that paper, the A matrix (constant strain storage coefficient matrix) only considers the fluid compressibility effect. The first file considers the internal structure evolution through the matrix A, but the fluid compressibility is ignored, see Zhang et al. (2022).

If you want to try anisotropic elasticity, you only need to change the following sentence in the AMCC_UMAT.m file:

if YIELD_VALUE < 1E-12 % Elastic

to

if YIELD_VALUE < 1E12 % Elastic

Post_processing.m has not been modified properly. The original purpose was to save the MATLAB results as a bunch of vtk files and import them into Paraview. paraview_script.py is also for Paraview.

It also contains the data CoolWarmFloat257.csv for cool-warm colormap.

Following figures (p1, p2, p1, p2) and (0.6 d, 0.6 d, 56 d, 56 d). The data unit is MPa. In double porosity theory, $p_1$ represents the micropore/nanopore/porous matrix fluid pressure, while $p_2$ represents the macropore/micro-fracture/natural fracture fluid pressure.