Abstract: With the applications of Newton-Krylov method in solving large sparse nonlinear equations, the design of linear preconditioners plays a vital role in the whole solver. In this paper, we study the application of different combinations of field-split (FS) preconditioners based on physical and domain decomposition methods to the unsteady flow problem of fractured porous media. Under the framework of domain decomposition technology, several new FS preconditioners are considered: the additive FS preconditioner, the multiplicative FS preconditioner, the Schur-complement FS preconditioner and the constrained pressure residual (CPR) preconditioner. The corresponding subsystems are approximately solved by the restricted additive Schwarz (RAS) algorithm. In order to further improve the performance of the FS preconditioner, we designe a two-level FS preconditioner. Numerical experiments on Tianhe-2 supercomputer show that the proposed preconditioner has a good robustness and parallel scalability.

Key words: Reservoir simulation, Restricted additive Schwarz algorithm, Field-Split preconditioner, Parallel computing