Productivity Simulation In Multi-stage Fractured Horizontal Well In Fracture-concentrated Sand Reservoir Based On The Finite Volume Method

With the promotion of petroleum industry,both the cost of horizontal wells drillings and the cost of hydraulic fracturing have decreased gradually in the past decades.As one of the most effective means in oil and gas reservoir stimulation,multi-stage fractured horizontal well lowers the payback period of investment,improves economy of project,and is commonly used in reservoir stimulation.Lots of researches have been conducted to analyze productivity in horizontal wells or vertical wells.However,these models is not accurate enough while simulating the seepage in fracture-concentrated sand oil reservoir.Underground hydraulic fracturing is so complicated that could depart from the vertical direction.In this case,analytic methods and semi-analytical methods must make a sacrifice in solution accuracy and set more limits.When it comes to numerical simulation methods,structural grids also have to face the problem in mesh coordinate transformation when reservoir become more complicated.Firstly,PEBI grids and structured grid are used to embody formation features.Under these grids,hydraulic fractures could vary its angle and length.Then,dual-porosity model is utilized to figure out the principle of interfacial flow between these two systems.Based on these grids and the Finite Volume Method,the selection of flow parameters is explained,and reservoir production model is dispersed.Therefore,this study will introduce these two methods to model the seepage in fracture-concentrated sand oil reservoir which is developed with multi-stage fractured horizontal well.Lastly,mainly due to the fact that obtained matrix is large,asymmetrical,and sparse,orthomin iterative method is used to solve system of linear equations.With the help of Matlab,underground pressure distribution and well productivity are solved for further analysis.After verification,this model is used for further analysis.Through the result of reservoir pressure distribution in fracture system and matrix system,we could find the contribution of natural fracture in improving formation permeability and the energy supplement from matrix system.Then,the theory of how various parameters combination in fracturing construction affect productivity is revealed.For reservoir stimulation,each index of hydraulic fracture has a ceiling value in stimulation effect.Hence,facing with a reservoir,it is not wise to expand fracturing scale to an extreme level.