A Nonlinear Solver with Phase Boundary Detection for Compositional Reservoir Simulation

Autor: Ouassim Khebzegga, Hamdi A. Tchelepi, Alireza Iranshahr
Rok vydání: 2021
Předmět:
Zdroj: Transport in Porous Media. 137:707-737
ISSN: 1573-1634
0169-3913
Popis: Compositional simulation is typically used to study subsurface displacement processes that involve complex physics. Such processes are highly nonlinear and they occur at the interplay of phase thermodynamics (phase stability and split) and rock/fluid interaction (relative permeability). To better characterize the convergence failures of compositional nonlinear solvers, we study the analytical and discrete forms of the component flux functions for the transport problem. We focus on isothermal, two-hydrocarbon phase models in the presence of viscous forces. Our analysis shows that the component flux function exhibits both kinks and inflection points, as described in the literature. We study the kinks due to the crossing of phase boundaries and we show their impact on residual terms. We, then, investigate the location, direction, and evolution of the inflection loci inside the two-phase region. Our findings suggest that these inflection loci may exhibit complex features, as a result of which an a priori determination of such loci is computationally prohibitive. We propose a nonlinear solver that detects phase boundaries and guides the Newton update to avoid crossing these boundaries. Our numerical results show that this phase change detection solver has superior performance in comparison with standard Newton solvers for a wide range of cases.
Databáze: OpenAIRE
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