Oil/Gas Pipeline Simulation Using a Segregated Method

The coupled method is usually used to solve the non-linear governing equations in oil/gas pipeline simulation applications, particularly for compressible fluid flow. In this paper, a segregated method with mesh refinement is proposed. The segregated method presents the advantage of the reduced computational memory and CPU time cost. In addition it also improves the convergence for the reason that the condition number is decreased as the matrix size is significantly reduced compared with the coupled method. In the presented method, a coarse mesh is adopted firstly. When the solution point for the nodes of this mesh is close enough to the optimal solution point, indicated by a certain criteria, a refine mesh is constructed by the solver thereafter. The value on the computing nodes for the refine mesh is computed by interpolation based on the previous solution point. Then the final solution for the refine mesh is obtained by the new segregated solver. Typical applications for oil/gas pipeline simulation are given. Results obtained by the method are compared with those obtained by using a “standard” software package to validate its accuracy. Results show that the average error between those solution obtained by different solvers is less than 1.0%. The efficiency of the new method is compared with the efficiency of a traditional coupled method. Numerical tests show that the method saves more than 50% of computational cost and the matrix size is reduced significantly.