Two‐phase flow in rough‐walled fractures: Comparison of continuum and invasion‐percolation models

摘要: [1] We present a systematic comparison study of simulating two-phase flow (drainage) in single heterogeneous fractures by using two fundamentally different approaches, namely, continuum-based model and an invasion-percolation (IP) model. We analyze both gravity neutral destabilized cases. In the continuum model, mass conservation equations for 2-D fracture plane are solved, based on modifications to TOUGH2, numerical simulator multiphase multicomponent transport geological media. A specific capillary pressure-liquid saturation function is used account sudden drainage local aperture location once its aperture-dependent nonwetting phase fluid entry pressure exceeded. Results from compared those IP that includes trapping. consider cases where contribution aperture-induced curvature term dominates over in-plane curvature. The shows presented can well reproduce results at low-capillary-number conditions furthermore also produce meaningful high-capillary-number regimes models not valid. Taking into viscous forces displacement process, examine effect number (reflecting injection rate) invasion. When rate varies low high, simulations show invasion pattern changes dominant fingers more homogeneous spreading and/or clusters with numerous tortuous fingers. This trend comparable previous experimental observations literature. numerically construct upscaled (fracture-scale) pressure-saturation relationship. relationship be fitted van Genuchten Brooks-Corey porous-medium-type models. Fracture behavior depends field heterogeneity. Simulation indicate increasing standard deviation leads smaller larger residual water saturation.