Effective Solution through the Streamline Technique and HT-Splitting for the 3D Dynamic Analysis of the Compositional Flows in Oil Reservoirs

Streamline approach is often used as an alternative effective method to classical finite difference technique for solving large heterogeneous fluid flow models in petroleum reservoirs. In the case of complex multi-component fluid system, this approach is scarcely used because the hydrodynamic and thermodynamic flow equations are strongly coupled through nonindependent variables including the pressure, the saturation and the species concentrations. It has been shown recently (Oladyshkin and Panfilov, Two-phase flow with phase transitions in porous media: instability of stationary solutions and a semi-stationary model. Third Biot Conference on Poromechanics, Norman, Oklahoma, USA, 2005; Oladyshkin and Panfilov, Comptes Rendus Acad Sci M´ecanique, Elsevier 335(1):7–12, 2007) that assuming quasi steady-state for the pressure field, the hydrodynamic and thermodynamic parts can be split into a set of equations that is referred as HT-split compositional model. In this work, the HT-split model is combined with the streamline technique. This approach has been implemented in gOcad using the StreamLab plug-in. The pressure field and the streamlines are computed using the finite volume flow simulator. The equations that govern the equilibrium between phases are solved separately using a classical nonlinear solver. A multi-component 1D solver has been implemented using the HT-split equations along the streamlines. Tools for visualizing the time evolution of species compositions have been also developed. Finally a simple case study illustrating the technique is presented. It is shown that the HT-splitting method coupled to the streamline technology provides an effective tool to solve complex problems involving multi-compositional flow for any 3D reservoir geometry and for any gas–liquid system. The advantage of such a technology is that the number of components is not limited.