# A Two-Stage Preconditioner for Multiphase Poromechanics in Reservoir Simulation

## TL;DR

This paper introduces a two-stage Newton-Krylov solver with a novel block-preconditioning strategy that enhances scalability, robustness, and convergence for large-scale multiphase poromechanics simulations in reservoir modeling.

## Contribution

The paper presents a new two-stage solution algorithm with a block-preconditioning approach that significantly improves the efficiency and scalability of multiphase poromechanics simulations.

## Key findings

- Rapid convergence demonstrated on benchmark problems
- Good parallel scalability achieved
- Robust performance with heterogeneous materials

## Abstract

Many applications involving porous media--notably reservoir engineering and geologic applications--involve tight coupling between multiphase fluid flow, transport, and poromechanical deformation. While numerical models for these processes have become commonplace in research and industry, the poor scalability of existing solution algorithms has limited the size and resolution of models that may be practically solved. In this work, we propose a two-stage Newton-Krylov solution algorithm to address this shortfall. The proposed solver exhibits rapid convergence, good parallel scalability, and is robust in the presence of highly heterogeneous material properties. The key to success of the solver is a block-preconditioning strategy that breaks the fully-coupled system of mass and momentum balance equations into simpler sub-problems that may be readily addressed using targeted algebraic methods. Numerical results are presented to illustrate the performance of the solver on challenging benchmark problems.