Numerical Simulation Study Of Fractured Horizontal Well Based On Finite Element Method

In recent years, with the increasing number of horizontal well and the improvement of fracturing in the reservoirs, the fractured horizontal technology has become a effective mean to improve the oil recovery ratio. It is necessary to research the production performance of horizontal well and its influence factors deeply for artificial fractured horizontal well application in oilfield.At present, the Finite Difference Method is the main method of numerical simulation study of artificial fractured horizontal well, using the equivalent resistance to simulate a small size crack in reservoir as a range of grids with large size in simulation; using the grid encryption technology to simulate a horizontal well as a series of well points which lines together in multiple grids. 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. The reasonable description of the horizontal wellborn and cracks has a great influence on the accuracy of the production performance prediction. In this thesis, the Finite Element Method is used to simulate the artificial fractured horizontal well. A finite element model of two-phase flow is established based on Finite Element Method theory. In this model, the matrix is discredited into quadrilateral elements. Fractures and wellborn are represented as one-dimensional line elements in two-dimensional. The backward-difference is adapted to discretized time. This method is adapted to solve the seepage problem with complex geometric shapes because of that it has more flexibility and accuracy than the Finite Difference Method.In this thesis, the production performance of horizontal well and its influence factors are studied by using a horizontal well in five-spot pattern. Many influence factors such as fracture number, fracture length, fracture interval and fracture conductivity are accounted. Several useful conclusions have been obtained according to the analyses of the pressure field, saturation field and dynamic curve getted from simulations. The Research shows that the fracture number, fracture length, fracture distance, fracture conductivity all have crucial influence on the production performance of the fractured horizontal well. But the parameter is not higher is better, there is a optimized value when other parameters are given.