Speaker
Description
We present a novel multiphase compositional model for geothermal reservoir simulation that explicitly accounts for phase separation phenomena and the representation of fractures.
Mass and heat transfer simulations in porous media typically incorporate temperature as an independent variable alongside other natural variables. However, the implementation of these simulations can be complex due to the need for variable substitution procedures when modeling phase transitions. In contrast, the overall composition formulation does not require such substitutions, as it involves persistent equations and variables in every cell. For simulating brine and steam systems with high enthalpies, we employ the overall composition formulation, replacing temperature with enthalpy as the state variable. The model is presented in a fractional flow form that is advantageous for numerical solution techniques.
Fractures are modeled as two-dimensional features within the three-dimensional porous medium, and we propose a mixed-dimensional extension of the compositional multiphase flow model to capture the intricate dynamics of high-enthalpy fractured geothermal reservoirs. This model enables robust simulation of fluid flow, heat transfer, and phase separation, while also accounting for interactions between processes in the fractures and the surrounding porous medium.
In terms of numerical methodology, our work introduces two significant contributions:
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We have developed a mixed-dimensional hybrid upwinding technique for
compositional flow, which enhances the numerical stability of
gravitational segregation in the presence of sharp density gradients. -
We have developed an efficient interpolation scheme for H2O–NaCl
brine correlations in pressure-enthalpy-composition (PHZ) space,
allowing complex thermodynamic properties to be integrated into the
simulation with both accuracy and efficiency.
Several simulations of complex flow dynamics, particularly in fractured geothermal reservoirs with challenging fracture network geometries, are presented.
| Country | Norway |
|---|---|
| Water & Porous Media Focused Abstracts | This abstract is related to Water |
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