Sleipner is a natural gas field located in the North Sea and is the first offshore project for carbon capture and storage. Since 1996, more than 10 million tonnes of CO₂ have been injected into the Utsira formation, 200 m underneath the Sleipner gas field. The injection has been subject to a large number of studies; the figure to the right, for instance, shows a seismic image of the CO₂ distribution in 2003 in the upper layer.

Herein, we consider a model made by Statoil to study the CO₂ in the upper layer and use the VE method implemented in MRST to study the physical assumption in the mode. Using a VE model reduces simulation times by at least one order of magnitude; runtimes for the simulations shown below were typically 2-10 minutes in our (nonoptimized) MRST code.

The figure below shows a comparison of simulations using the original data, and simulations where we have increased the permeability by a factor three, decreased the porosity by a factor 0.6, and decreased the density by a factor 2/3. The result is a significantly better match with the seismic data.

Reference (comparison of MRST with 3D and VE simulations in Eclipse):

• H. M Nilsen, P. A. Hererra, M. Ashraf, I. Ligaarden, M. Iding, C. Hermanrud K.-A. Lie, J. M. Nordbotten, H. K. Dahle, and E. Keilegavlen, Field-case simulation of CO₂ -plume migration using vertical-equilibrium models. Energy Procedia 2011, DOI: 10.1016/j.egypro.2011.02.315.