Gas Transport in Clays: Dilatation, Dry out, and Behavior Transitions

Abstract:

Gas transport in clays is an important consideration for engineered bentonite barriers for nuclear waste storage, carbon storage beneath clay-bearing caprocks, and leakage from gas storage reservoirs. We examine a coupled multiphase thermal-hydrological-mechanical-chemical continuum model for gas transport applicable to these scenarios that couples phase field methods for quantifying phase boundaries, visco-elasto-plastic rheology, and gas-water-clay interaction. The model in various limits is validated against Hele-Shaw experiments and analog materials involving polymers, oedometric compression tests, and CO2-brine co-injection experiments in dual porosity media. We compare fourth-order Hillard-Cahn and second order Allen-Cahn approaches for describing dilatation and fracture growth. Transitions in behavior, including the viscous fingering to fracture transition and a transition from stable to oscillatory flow are described.

Sandia National Laboratories is a multimission laboratory managed and operated by National Technology and Engineering Solutions of Sandia, LLC., a wholly owned subsidiary of Honeywell International, Inc., for the U.S. Department of Energy’s National Nuclear Security Administration under contract DE-NA-0003525.