A Numerical CO₂ Laboratory

The main objective is to develop an open-source code for modelling of CO₂ storage. Main activities are:

•    Establish a platform for development and implementation of new modules that makes it possible for researchers to test state-of-the-art algorithms.
•    Develop a credible simulation tool by modelling and simulation of real CO₂ storage projects.
•    Benchmarking to develop common standards and methods

The numerical laboratory currently consists of two parts. The first part is a free, open-source software for vertical equilibrium (VE) simulation of CO₂ storage:

•    Assuming vertical equilibrium, the migration of a thin CO₂ plume can be approximated in terms of its thickness to obtain a 2D simulation model in which the effect of the heterogeneities in the underlying medium is preserved. This type of model is particularly efficient for studying structural and residual trapping under an impermeable caprock.
•    Using a VE model reduces simulation times by at least one order of magnitude compared with traditional 3D simulation. Moreover, the numerical errors induced by a VE model will in many cases be significantly smaller than the errors introduced by the overly coarse resolution needed to make 3D simulation models computationally tractable. VE simulations can therefore be used to increase the lateral resolution and/or to quickly study the physical assumptions of the flow model.
•    The software is implemented as a separate module in the Matlab Reservoir Simulation Toolbox (MRST) and is accompanied by a set of tutorials and C-routines for accelerated computations.
•    The VE module has been applied to study CO₂ migration in the upper layer of Sleipner, using a model that is publicly available from the ieaghg.org website. The low runtime of the simulator enabled us to interactively study how changes in key model parameters affect the flow behaviour. By increasing the permeability by a factor three, decreasing the porosity by a factor 0.6, and decreasing the density by a factor 2/3, we obtained significantly better match with seismic data than what has been observed in previous simulations using 3D tools.
•    In the IGEMS project, the VE module was used to study how the reliefs in the top seal may retard plume migration and significantly impact structural and residual trapping.

The second part is a free, open-source, reservoir simulation software:

•    The software is implemented in C/C++ as part of the Open Porous Media (OPM) initiative and is mainly based on simulation tools developed previously at SINTEF and Stuttgart University.
•    The software offers traditional two-phase and three-phase flow models; support for advanced well handling and gridding (Cartesian, stratigraphic grids, fully unstructured grids); and comprehensive routines for parsing the input from industry-standard geomodelling tools.
•    The software can be used to model both the injection period and the post-injection migration of CO₂ and has in particular been validated on a sector model of the Johansen formation.