Hybrid multiscale modeling through direct substitution of pore-scale models into near-well reservoir simulators

A hybrid, multiscale reservoir simulator has been developed that directly substitutes pore-scale models for continuum-scale, finite-difference grids. Over 7500 pore scale models (∼75 million pores) are inserted into a ∼1 m ² pore-scale region around a producing well, which is coupled to an outer, fine-scale finite-difference model with 10 000 cell-centered grids. This computationally demanding problem is possible because the domain is decomposed into manageable subdomains (thousands of pore-scale models and one continuum region) and then coupled together using finite-element mortars to ensure continuity between the subdomains. Here, flow is single-phase, single-component, and steady-state, but the potential of the simulator for more complex, near-well flows is demonstrated. A priori, direct upscaling and a posteriori, global upscaling are both performed, and it is shown that the direct approach results in significant inaccuracies in the pressure and flow fields but the global upscaling approach results in a good approximation.