The Reservoir Numerical Simulation Of The Oil And Water Two-Phases Flow Based On The Full-Implicit Method

Reservoir numerical simulation is a numerical method simulating the seepage laws and the seepage flow in the reservoir,it plays a very important role in the field of petroleum engineering,which can be used to do a research and make reasonable plans for optimal reservoir development and enhance oil recovery.Based on reservoir engineering,fluid mechanics in porous medium,numerical mathematics and computer programming,reservoir numerical simulation can be utilized to solve multiple physical quantities such as pressure and saturation.In the actual reservoir development process,most models usually need to reveal the flow law which generally used to build a group of mathematical model,and oil and water two-phase mathematical model is the most popular model of these models.Oil and water two-phase flow mathematical model is a definite solution of the problem consists of a set of nonlinear parabolic partial differential equations with appropriate boundary and initial conditions and auxiliary equations.We choose the oil and water two-phases flow based on the full-implicit method because of that the model has a strong nonlinearity which greatly increased the solving difficulty,and the fully implicit method has the highest stability of many solutions.The paper introduces two methods such as corner-grid mesh and block-center mesh to solve this problem,it also uses full-implicit numerical dispersion to the flow equation to get a set of nonlinear algebraic equations,then uses the Newton-Raphson method to linearize the nonlinear equations and obtains the iterative solution.In the solution process,we focus on the calculation of transmissibility between grids,the initialization of relevant unknown variables,the problem of conversion between different states,the special treatment of average density and crossflow.Several examples are given in order to test the accuracy of our method,we compare the results solved by our method and the software Eclipse.The errors are within the allowable range.