3D 2Phase Reservoir Numerical Simulation Studies Based On Finite Element Method

Artificial Fracturing technique is a valid reform measure in low permeable reservoir development. In the process of fracturing and stimulation ,the fracture generated is complicated and variable.How to properly depicribe the fracture shape and to simulate the production performance of fractured well is very significant to guide the development of low permeable reservoir. At present,most assumptions are that handled the fracture as stretches linearly rectangle fracture on the numerical simulation study of artificial fractured well.Which doesnot reflect the real situation,and complicated fracture simulations arenot in depth,the proper description of fracture more in conformity with the reality is ont acquired.Therefore,it needs to make a deep study.At present, the Finite Difference Method is the main method of numerical simulation study of artificial fractured well,using the equivalent resistance to simulate a small size crack in reservior as a range of grids with large size in simulation.But,this method has large difference from the actual situation of the reservoir and has limitations in dealing with the seepage problem with complex geometric shapes.In this thesis,basing on theory of finite element method,combining with low permeability reservoirs and the characteristic of the artificial fracturing well problem,the three-dimensional two-phase flow Finite element seepage numerical sitmulation method are established.In this model,the matix is discretized into quadrilateral elements.Fractures are represented as two-dimensional surfaces elements in three-dimensional.The meshes of matrix use the arbitrary tetrahedron element. A mumerical simulator is established by FORTRAN and get steady results.This method is adapt to solve the seepage problem with complex geometric shapes because of that it has more flexibility and accuracy than the Finite Difference Method.Started with the basic radial flow model,it validates the practicability of simulator, provides basis for complicated fracture simulation.The production dynamic change rules of artificial fracture are studied such as non-uniform depth extened fracture, curved surface fracture,steering extened fracture,non-uniform depth-extened-curved surface fracture.Several useful conclusions have been obtained according to the analyses of the pressure field,saturation field and dynamic curve getted from simulations and supply new methods to numerical simulation study of artificial fractured well.