Meshless Numerical Well-Test On Complex Fault-Block Reservoir

Due to the fast development of oilfields, more and more complex fault-block oil reservoirs have been opened up in recent years while the water injection makes the fluid flow more complicated. Thus those traditional theories and analysis methods of testing interpretation became less efficient and could not meet all requirements exactly in the development.Finite-difference and Finite Volume Method are two widely-used numerical calculation methods in this field at present. Both base themselves on meshes, thus cannot avoid being subjected to their influences;While meshless method is free from meshes and the result it achieves turns out more accurate. The two merits make this newly- sprouted numerical method one of the hottest tasks nowadays.Taken the weighted residual method with compactly supported trial function as mathematical model, the fundamentals of meshless method have been explicitly discussed in this paper;Meshless method has also been inducted into numerical well test analysis. And then the two meshless methods, namely Element-Free Galerkin Method (EFGM) and Meshless Weighted Least-Square Method (MWLS), have been applied to the solution of oil-water two-phase flow through porous media;Combining with complex fault-block oil reservoirs well-test analysis's features, the meshless nodes distribution has been investigated thoroughly; Resolution of system of linear equations as well as the borehole storage and skin factor effects have also been analyzed: simulated annealing global optimization algorithm for automatical-fit in well-test interpretation has been adopted. The meshless well-test software basing on this technique has already been developed and applied in the practice of oilfields, and satisfactory results were obtained.The simulation results indicated that the EFGM is of high computational accuracy and stability, but accompanied by big calculated amount; MWLS could instead overcome the defects of EFGM and greatly improve computational efficiency, but its Eulerian equation changed thus might lead to certain errors under non-accurate boundary conditions.The approach introduced in this dissertation abstracts the merits of the two methods mentioned above (MWLS & EFGM) to achieve discrete resolution and deals different parts with different measure: the former being used in the field of pressure control equation while the latter in saturation equation.The meshless well-test software grounded on such approach as been developed and applied in the scene of oilfields. Fascinating statistics proved to be of high accuracy and efficiency. On-site testings also make clear that the approach is very practicable in practical application.