ELK: a MOOSE framework based computational tool for modeling electro-hydraulic fracturing

ABSTRACT: Multistage hydraulic fracturing has revolutionized the oil and gas industry, particularly enabling the rapid growth of shale gas production in the U.S. However, for unconventional subsurface resource recovery, such as geothermal energy extraction in super-hot formations and in situ mineral leaching, hydraulic fracturing faces significant challenges, including packer leakage, short-circuiting, insufficient surface area for effective reactions, and water contamination. Electro-hydraulic fracturing - a combination of electric shocking, thermal shocking, and hydraulic fracturing - has been proposed to address these issues. Laboratory results have shown great promise for this technology in unconventional subsurface stimulation. However, scaling it up and deploying it in the field requires guidance from numerical simulations. This paper presents ELK (ELectro-fracKing), a computational tool designed to model electro-hydraulic fracturing processes. ELK is built on the open-source, parallel MOOSE (Multiphysics Object-Oriented Simulation Environment) framework, using the finite-element method. ELK solves the momentum balance and mass conservation equations for hydraulic fracturing using numerical techniques such as the discontinuous Galerkin method, cohesive zone models, and multiphase, multicomponent fluid-flow simulations. This allows ELK to simulate proppant-fluid mixture-driven fracture propagation, proppant transport and settling, and fracture closure with proppant compaction. ELK solves the coupled dynamic hydromechanical governing equations for electric shocking (i.e., pulsed-power-induced fracturing). A damage model and permeability and stiffness evolution constitutive laws have been incorporated to simulate multi-fracture propagation in saturated environments. ELK solves part of the Maxwell Equations for thermal shock under low and constant current frequency (i.e., electro-quasi-static). We validate each modeling capability against laboratory results and analytical solutions. ELK offers a valuable computational tool for advancing unconventional subsurface resource extraction.