The Research Of Equivalent Permeability Calculation For Fractured-Vuggy Carbonate Reservoir

Due to the properties of multiscale and strong heterogeneity in fractured vuggy carbonate reservoir, regular numerical simulation methods in the development process are not available while the flow process of oil and gas become very complex. Under this background, equivalent media method is proposed for numerical simulation in fractured vuggy carbonate reservoir. The essence of equivalent media is that, basing on flow rate equivalence, the grid with fracture and vug is considered as homogeneous, and the heterogeneity is contained in the grid equivalent permeability tensor, the key part of this method is the calculation of equivalent permeability tensor in the grid with fracture and vug. Hence, the main contents of this dissertation are described as follows. First, research status of fractured vuggy carbonate reservoir development at home and abroad is introduced, while the present common mathematical model of fluid flow in fracture and vug and determination methods of rock equivalent permeability tensor are investigated, a simple introduction is given for numerical simulation model and control volume numerical simulators in fractured vuggy carbonate reservoir. Then, tensor calculation model is built with statistic data and simplified grid in fractured and vuggy reservoir based on the principle of equivalent permeability tensor, meanwhile, the corresponding theory derivation and numerical calculation method are shown with the characteristics of pore fractured media grids and fractured vuggy media grids. Finally, summary and suggestions are given for this dissertation. The results show that boundary element method is an effective tool to calculate the gird equivalent permeability, and the periodic boundary condition can guarantee the solution of symmetrical positive definite matrix of equivalent permeability tension; the macro equivalent flow equation of fracture-vugged grid system was derived by homogenization theory and the theory solution of equivalent permeability tension was acquired, also the finite element method is an effective method to calculate the equivalent permeability tension.