A fully-implicit solving approach to an adaptive multi-scale model -- coupling a vertical-equilibrium and full-dimensional model for compressible, multi-phase flow in porous media

TL;DR

This paper introduces a fully-implicit, adaptive coupling method combining vertical equilibrium and full-dimensional models to efficiently and accurately simulate multi-phase flow in porous media, especially for elongated storage geometries.

Contribution

It presents a novel fully-implicit, adaptive coupling framework that unifies vertical equilibrium and full-dimensional models for improved simulation accuracy and efficiency.

Findings

Adaptive model achieves high accuracy and efficiency.

Suitable for elongated storage geometries.

Monolithic, fully-implicit solution approach.

Abstract

Vertical equilibrium models have proven to be well suited for simulating fluid flow in subsurface porous media such as saline aquifers with caprocks. However, in most cases the dimensionally reduced model lacks the accuracy to capture the dynamics of a system. While conventional full-dimensional models have the ability to represent dynamics, they come at the cost of high computational effort. We aim to combine the efficiency of the vertical equilibrium model and the accuracy of the full-dimensional model by coupling the two models adaptively in a unified framework and solving the emerging system of equations in a monolithic, fully-implicit approach. The model domains are coupled via mass-conserving fluxes while the model adaptivity is ruled by adaption criteria. Overall, the adaptive model shows an excellent behaviour both in terms of accuracy as well as efficiency, especially for elongated geometries of storage systems with large aspect ratios.