Study On Inflow Characteristics Of Multi-Stage Fractured Hilly-Terrain Horizontal Well In Shale Reservoir

Multistage fracturing in horizontal well is the main approach to extract oil and gas resources from shale reservoirs,yet due to reservoir anisotropy,stress difference,and drilling technology’s limitations,horizontal wells inevitably exhibit hilly-terrain trajectory,where depth difference exists,and hydraulic fractures are not always perpendicular to the horizontal well trajectory.Therefore,based on existing well productivity models,a multi-segment well model considering hilly-terrain trajectory is proposed herein by introducing additional pressure drop into the wellbore flow conservation equation.Meanwhile,this study defines hydraulic fractures along the multisegment well,generates random natural fractures by using the projection-based embedded discrete fracture model,and establishes a shale reservoir model based on nonDarcy black oil model.The reservoir model,coupled with the multi-segment well model,resorts to the MATLAB Reservoir Simulation Toolbox sequential implicit coupling framework and applies the Newton-Raphson method to iteratively solve the horizontal well productivity in shale reservoir.The model is then verified by field application,with simulated results highly consistent with the measured data.By using the model,flow characteristics in asymmetric or inclined hydraulic fractures are studied,uneven inflow from fractures with their contribution to overall well productivity are investigated,and furthermore the influence caused by the hilly-terrain well trajectory on the above phenomenon is analyzed.At last,the sensitivity analysis of the potentially influencing factors on the simulation is conducted.