Extending the persistent primary variable algorithm to simulate non-isothermal two-phase two-component flow with phase change phenomena

Abstract

In high-enthalpy geothermal reservoirs and many other geo-technical applications, coupled non-isothermal multiphase flow is considered to be the underlying governing process that controls the system behavior. Under the high temperature and high pressure environment, the phase change phenomena such as evaporation and condensation have a great impact on the heat distribution, as well as the pattern of fluid flow. In this work, we have extended the persistent primary variable algorithm proposed by (Marchand et al. Comput Geosci 17(2):431-442) to the non-isothermal conditions. The extended method has been implemented into the OpenGeoSys code, which allows the numerical simulation of multiphase flow processes with phase change phenomena. This new feature has been verified by two benchmark cases. The first one simulates the isothermal migration of H 2 through the bentonite formation in a waste repository. The second one models the non-isothermal multiphase flow of heat-pipe problem. The OpenGeoSys simulation results have been successfully verified by closely fitting results from other codes and also against analytical solution.

Remediation Potential of Borehole Thermal Energy Storage for Chlorinated Hydrocarbon Plumes: Numerical Modeling in a Variably-Saturated Aquifer

“…In the above equations, the classical Millington (MILLINGTON, 1959) formulation is used for the effect of tortuosity. Since we also need to consider the non-isothermal effects in this study, the energy balance equation (assuming local thermal equilibrium) for a two-phase system reads (Class and Helmig, 2002;Huang et al, 2015)…”

“…The implemented model has been validated against several benchmark problems. Since the heat and mass transfer of the original two-phase two-component model was already validated (Huang et al, 2015;Huang, 2017), only the mass transport portion for the third component (organic contaminant) is validated here. To do this, the experimental data of measured gas phase TCE concentration from McCarthy and Johnson (1993) along with the semianalytical solution given by Atteia and Höhener ( 2010) was compared with model simulation.…”

“…In Eqs 18-20, it is assumed that S L > S rL . However, to account for the possible drop of S L below residual saturation S rL due to heating of partially-saturated soil, the original capillary pressure curve is modified according to Huang et al (2015) by linear extrapolation to the segment where S L #S rL . This leads to an extended vG curve with P max cap 1.46 × 10 8 Pa at S L 0.…”

“…By analyzing the TCE flux from the saturated to unsaturated zone and eventually into the atmosphere, favorable conditions for the enhanced attenuation of CHC plumes resulting from BTES operation were delineated and discussed. Nonlinear coupled multiphase flow, mass and heat transport equations were developed and solved using the finite-element simulator OpenGeoSys (Kolditz et al, 2012;Huang et al, 2015). The results can improve the understanding of thermal energy storage at contaminated sites and contribute to a safe and beneficial combination of underground heat storage and groundwater remediation.…”

An All-At-Once Newton Strategy for Marine Methane Hydrate Reservoir Models

“…A number of different numerical methods have been developed to handle the gaseousaqueous phase transitions in multi-phase multi-component porous media models, e.g., primary variable switching (PVS) schemes [47,8], method of negative saturations [41], method of persistent variables [40,26], and non-linear complementary constraints (NCP) approaches P r e p r i n t An all-at-once Newton strategy for methane hydrate reservoir models 3 [36,34,3,5]. In the most widely used gas hydrate reservoir simulators, e.g., TOUGH-Hydrate [38], HYRES-C [29,28], STOMP-HYD [45], HRS [39], etc., the gaseous-aqueous phase transitions are handled using the PVS schemes, where the choice of the primary variables is adapted locally to the phase state.…”