| dc.description.abstract | The main objective of this thesis has been to investigate some methods for simulating CO2 storage and hydrocarbon recovery on complex polyhedral grids, with main focus on the nonlinear two-point flux approximation method. The industry standard has for many years been the (linear) two-point flux approximation method, but as this method only calculates the flux across an internal face by approximating the transmissibilities as averages between two cells, it does not account for transverse flux across the face making it inconsistent for problems where transverse flux occurs. The nonlinear two-point flux approximation method does take transverse flux into consideration, and so it is of interest to implement it as a part of SINTEF's Matlab Reservoir Simulation Toolbox (MRST).
This thesis will begin by going through the physical aspects of the flow equation and it's discretization. We will follow up by deriving the linear and nonlinear two-point flux approximation methods, as well as a multipoint flux approximation method. Further, use and syntax of MRST is presented, together with explanation of the written code. Through a few examples and comparisons, we investigate the robustness and accuracy of the nonlinear two-point flux approximation method compared to established solvers in MRST. It is shown that the nonlinear two-point flux approximation method is versatile and an equally good candidate compared to other established methods within reservoir simulation. However, it is sensitive to full permeability tensors on complex grids, and thus, as is, ineffective for the purpose it is intended. | |
