The domain decomposition method

when combined with flexible decomposition and load-balancing strategies

can improve the parallel performance of iterative computations and save the costs in large-scale numerical reservoir simulations.However

the ordinary domain decomposition method was found to have problems of increased computational load and slowed convergence

especially in working with non-uniform domain numerical simulations.Here

we report the results of an efficient parallel approach that we have recently designed and implemented.This approach used preconditioned domain decomposition method and load-balancing strategy based on the distributed parallel environment to reduce the computational complexity of non-uniform numerical reservoir simulations and enhance the computational speed.Our computational results showed that the simulation speed was improved largely with a high speedup.