Low Permeability Deformable Medium Reservoir Seepage Model And Calculation Method

With the exploitation of the oil resource, the proportion of low permeability reservoirs has been under increasing. To fully recognize the percolation law of the low permeability reservoir is of great significance in developing the reservoir reasonably and effectively. It is showed by many laboratory experiments and field exploration that the percolation of low permeability reservoir must overcome the starting pressure gradient to be able to flow. Second, the primitive permeability and porosity are very low in the exploitation of low permeability reservoir, and the relative range of variation of the permeability and porosity still has great effect on the exploitation of the oil resource. Therefore it is necessary to consider the influence of the deformation of the media At present, the research of low permeability reservoir mainly concentrates on the influence of some single factor on the well test models, for example, only considering the starting pressure gradient or the deformation of the mediaBased on the analysis of the percolation regulation of low permeability reservoir, the well test models of the single media and the dual media in low permeability reservoirs are built in this paper, considering not only the influence of starting pressure gradient and deformation of the media, but also of the wellbore storage and skin effect. The models can be mathematically summarized into the definite solution of nonlinear parabolic equations. Comparing the difference algorithms for the nonlinear parabolic equations, this thesis adopts the predictor-corrector method, which has good stability and convergence to obtain the solution of the models. The accuracy of the numerical method is analyzed. Then the numerical programs for the models are designed by Visual C# in this paper, and the numerical solutions of the models are solved by the program. At last, taking the dual media model as an example, this thesis analyzes the influence the following factors on the pressure responses, including starting pressure gradient, media deformation, wellbore storage and skin factor. The variation rules of pressure are analyzed when considering or neglecting the starting pressure gradient and the deformation of the media And the sensitivity of starting pressure gradient and permeability modulus is comparatively analyzed. The pressure type curves are plotted too. The study has applicable value for well test analysis in the low permeability reservoir.