Integrated LSM-DFN Modeling of Naturally Fractured Reservoirs: Roughness Effect on Elastic Characteristics

On the Determination of Coordination Numbers of Coupled DEM-DFN Model for Modeling Fractured Rocks

“…The coupled DEM-DFN model for fractured rocks combines the rock matrix and fracture geometries represented by DEs and DFs, respectively. The DFN is merged into the background DEM in a simple yet efficient way, where the DE links that cross DFs are removed (Curtin and Scher, 1990;Liu and Fu, 2020a;Liu et al, 2021). In this section, we will introduce the coupled DEM-DFN model in detail.…”

“…First, the coordinates of mass DEs are generate within a specific area, with the contacts between DEs defined properly. Then, the corresponding DFN, created by fracture attributes, is merged into the DEM, where the contact links crossing the DFs are removed (Curtin and Scher, 1990;Liu and Fu, 2020a;Liu et al, 2021). The force and moments acting on each DE are calculated, such that the position of DEs can be updated by a central difference scheme.…”

“…Granular textures, particle-scale kinematics, and force transmission can be correlated at the microlevel (Cowin, 2004), constituting a powerful tool to study the effect of microstructures on the macroscopic properties of rocks. The DEM now appears as an efficient numerical method to handle most of the problems with rock masses, such as material heterogeneities, irregularly geometric characteristics, nonlinear large deformations, and progressive failure through nucleation and propagation of microcracks (Zhao, 2010;Jiang et al, 2017;Liu and Fu, 2020a;Liu et al, 2021). It is worth to mention that Murphy and Fehler (1986) conduct a DEM modeling for hot dry rocks of enhanced geothermal systems and attribute microseismic responses to shear slip along the joints in rocks.…”

“…For this purpose, we conduct a series of numerical experiments by applying the coupled DEM-DFN 2D model to emulate fractured rocks. We assume a homogeneous rock matrix, which is widely used in the available studies (Lei et al, 2017;Liu and Fu, 2020a;Liu and Fu, 2020b;Liu et al, 2021). Also, we keep a simple formulation of the DEM (i.e., spherical particles and linear elastic contact laws) for high calculation efficiency.…”