The Non-linear Flow Analysis Of Finite Conductivity Vertically Fractured Wells In The Low Permeability Reservoir With Deformed Triple Porosity Medium

The natural productivity in the low permeability reservoir is low and the reservoir frequently needs to be reformed through some stimulation treatments. One of the most popular methods is the hydraulic fracturing treatment. Fracturing can form a vertical fracture with high conductivity in the low permeability reservoir, which expands seepage area of oil and so increases the productivity of oil wells. However, the success of the well stimulation is not guaranteed. We need to rely on the well testing method to estimate reservoir parameters and predict reservoir performance after the treatment in order to evaluate the efficiency of the fracturing treatment. The key to the well testing job is building an effective well testing interpretation model which could fully reflect the characteristics of the fluid flow in the reservoir.Fractures-vugs carbonate low permeability reservoirs have a very wide distribution in China, but some oil wells initially have no productivity unless implementing a fracturing process. Hence, the study on vertically fractured wells in the low permeability reservoir with deformed triple porosity medium is very practical. In consideration of both the flow characteristics that there existed a start-up pressure gradient in the low permeability reservoir and the deformation of the medium in the stress-sensitive formation, the fluid flow in the vertical fractures and formation was divided into two regions--the linear flow region in the vertical fractures and the non-linear flow region in the low permeability reservoir with deformed triple-porosity medium following Cinco-Ley H.'s bilinear flow theory of finite conductivity vertically fractured wells. As a result, the non-linear flow model of finite conductivity vertically fractured wells in the low permeability reservoir with deformed triple porosity medium was constructed. Due to the nonlinearity of the model, stable finite difference schemes were adopted to get its numerical values. Typical west test curves were plotted by using these numerical results. Finally, the dynamic sensitive effects of dimensionless conductivity of vertically fractured wells, dimensionless start-up pressure gradient, deformation factor, parameters of triple-porosity medium and coefficients of wellbore storage and skin effect towards the dimensionless wellbore pressure and its derivative were discussed.