State-of-the-art technology in reservoir characterisation allows for the generation of high-resolution reservoir models with multimillion cells. Moreover, increased demands for assessment of uncertainties and history matching require fast and accurate flow simulations on multiple plausible geological models on a routinely basis. Conventional reservoir simulators fail to fulfil this need. This has lead to a revival of streamline simulators based on time-of-flight coordinates.

Streamline methods

The department has a long history of cooperation with the FrontSim-group within Schlumberger GeoQuest, dating back to the former company Technical Software consultants. In a previous project, ComSim (1997-99), we worked on expanding the FrontSim streamline simulator to include three-phase and compositional features. Currently, we are working on development of other aspects of the streamline technology in FrontSim.

Fast marching methods

In a joint effort with researchers at University of Bergen and University of Oslo we have developed an alternative to streamline computations. The method has two key ingredients:

1. A reformulation of the advection of fluid saturations into a steady time-of-flight equation and one-dimensional Buckley-Leverett equations for the transport of saturations
2. Efficient solution of the time-of-flight equation using a variant of the fast-marching method

The method has the accuracy and the efficiency of streamline methods, but avoids the geometrical complexity inherent in representing individual streamlines.

The research is conducted in two separate parts: one part is academic research conducted by our academic partners and through a BeMatA project, and one part is contract research for an industrial client. The latter part is confidential and further details cannot be described.

References

1. K. Hvistendahl Karlsen, K.-A. Lie, and N. H. Risebro. A fast marching method for reservoir simulation. Comput. Geo., 4(2):185-206, 2000.
2. K. Hvistendahl Karlsen, K.-A. Lie, J. R. Natvig, and N. H. Risebro. A fast marching method for 3D reservoir simulation. In "Proceedings of the 13th Nordic Seminar on Computational Mechanics (NSCM-13)", Eds., J. Hellesland, H. Osnes, and G. Skeie, pp. 147-150, Mechanics and Applied Mathematics Series, No. 7, University of Oslo, Norway, October 2000.
3. I. Berre, H. K. Dahle, K. Hvistendahl Karlsen, K.-A. Lie, and J. R. Natvig. Time-of-flight + fast marching + transport collapse: an alternative to streamlines for two-phase porous media flow with capillary forces?  in  Proceedings of the XIVth International Conference on Computational Methods in Water Resources (CMWR XIV) , June 23-28 2002, Delft, The Netherlands,  Eds., S.M. Hassanizadeh, R.J. Schotting, W.G. Gray, and G.F. Pinder, Developments in Water Science, vol 47, pages 995-1002, Elsevier, 2002.