Imposing Convergence Constraints on Multiscale Mehods for the Efficient Solution of Multiphase Flow Through Naturally Fractured Porous Media

This work investigates the possibility of using an incompletely converged pressure solution in the sequentially implicit loop, traditionally used to simulate multiphase flow through porous media. This is made possible through the Multiscale Finite Volume (MSFV) formulation, which was recently extended to include fully integrated basis functions which account for contributions from wells and fractures [Tene et al, SPE RSS 2015]. Here, we take this method one step further towards multiphase flows, by adding a conservative flux reconstruction stage and pairing it with a fine-scale transport solver. In our experiments we monitor the convergence behaviour while adaptively varying the tolerance level for the pressure solution. Finally, we conclude that only few iterations of the multiscale pressure solver are sufficient to obtain results which are meaningful for decision-making, especially given the fact that, in practice, the reservoir specification is subject to geological uncertainties.