Verification benchmark for a single-phase flow hydro - mechanical model comparison between COMSOL Multiphysics and DuMuX

Dejian Zhou,Alexandru Tatomir,Martin Sauter,Ingrid Tomac,J.S Mccartney,I Tomac

doi:10.1051/e3sconf/202020502002

Abstract

Numerical modelling of hydromechanical processes in geological environments has become an invaluable tool in understanding and predicting system behaviour. However, due to the different algorithms and numerical schemes implemented in the different models, model reliability may vary considerably. Modelling of single- and multi-phase flow in porous media has been widely employed in various engineering applications such as geological disposal of nuclear waste, geological storage of carbon dioxide, high-temperature geothermal systems, or hydraulic fracturing for shale gas exploitation. Coupled hydro-mechanical (H-M) processes play a key role in the prediction of the behaviour of geological reservoirs during their development and testing operations. In this paper, we present a benchmark test on a single-phase flow problem in a hydrogeological reservoir with 5 horizontal layers of different properties. The aim is to compare two hydromechanical (H-M) models that use a vertex-centred finite-volume discretization and a finite element discretization. The first model is constructed with the free-open source simulator DuMuX, and the second with the commercial software COMSOL Multiphysics. The verification study suggests general confidence in the model reliability, but also highlights and discusses several areas of discrepancies between two models.

Highlights

Hydrogeological problems are generally difficult to study directly because the subsurface structures are not accessible to direct studies and characterisation
COMSOL Multiphysics is a commercial software known for a flexible implementation environment and a capacity to couple different physical processes
The comparison of the two simulators is further provided as breakthrough curves at different observation points, and as plots of parameter of interest over horizontal planes at different depth

Summary

Introduction

Hydrogeological problems are generally difficult to study directly because the subsurface structures are not accessible to direct studies and characterisation. Modelling is a widely utilized tool for understanding the influence of complexity in geometry, heterogeneity in the respective properties (mechanical, hydraulic, etc.) as well as the effect of process coupling, such as thermo-hydromechanical-chemical (THMC) processes. Various numerical simulators such as TOUGH-FLAC (Rutqvist, 2013), CODE-BRIGHT (UPC, 2002) and DuMuX (Flemisch et al 2011) etc. This paper presents the results of a benchmarking study on the hydro-mechanical (H-M) effects induced by a single-phase fluid injection into a fully saturated multi-. COMSOL Multiphysics is a commercial software known for a flexible implementation environment and a capacity to couple different physical processes. At one time-step, the flow solution is calculated and the effective pore pressure is used for the calculation of stresses and mechanical deformations

Model setup

Overpressure

Displacement

Stress

Conclusion