Productivity Evaluation Model Of Tight Oil Reservoir Stage Fractured Horizontal Well

Tight oil,the reserves of which account for a great proportion in oil reserves of China,is an important unconventional resource.However,due to low permeability and porosity as well as the presence of the starting pressure gradient,it is difficult to develop tight oil reservoir.Multi-stage fractured horizontal well is often employed to increase the drainage area of oil and water,making the flow law more complicated.Thus,it is essential to perform the production analysis of multi-stage fractured horizontal well.In this thesis,the production of multi-stage fractured horizontal well is predicted with analytic method and numerical simulation.In this thesis,percolation law of fractured horizontal well was studied through numerical simulation method.Tight oil reservoir is divided into several flow zones such as elliptical flow zone,fracture radial flow zone,horizontal well pressure drop flow zone.Considering starting pressure gradient and horizontal well pressure drop,steady-state production model of tight oil reservoir fractured horizontal well has been proposed.Using conformal transformation and iterative method,production model is solved;meanwhile,the result obtained by steady-state production model is compared with that obtained by other scholars' model.Fractured horizontal well production parameter optimization is obtained by this method.Based on double-medium model,unsteady-state production model of tight oil reservoir fractured horizontal well has been built taking non-Darcy flow into consideration.The result obtained by unsteady-state production model is compared to the result obtained by Eclipse.The effect of nonlinear flow on oil production and variation law of production are analyzed.Factors that influence oil production,such as matrix permeability,matrix porosity fracturing stages and fracture half-length are compared.Main controlling factor of horizontal well production is obtained by sensitivity analysis.The study of this thesis displays guiding significance to production evaluation,selection of optimal production scheme as well as improving the recovery of tight oil reservoir.