PRESSURE TRANSIENT MODEL OF MULTI-STAGE FRACTURED HORIZONTAL WELL WITH INDUCED FRACTURE FOR HETEROGENEOUS STIMULATED RESERVOIR VOLUME

In order to simulate accurately wellbore pressure transient performance of multi-stage fractured horizontal well (MFHW) with the complex fracture network and heterogeneous in tight oil reservoirs, an unsteady seepage mathematical model of the MFHW with induced fractures in rectangular heterogeneous reservoir is established. The wellbore pressure solution is obtained by coupling the fracture model, the reservoir model and heterogeneous reservoir interface model. The wellbore pressure accuracy of the two heterogeneous reservoir models is verified by numerical solutions, boundary element method and previous model. By flow stages analysis and parameters sensitivity analysis, the following results can be obtained. Compared with the wellbore pressure derivative curve of the MFHW in homogeneous reservoir, the unique flow stages of this model in the ideal case include: the complex linear flow stage, the "supply" stage from induced fractures to fractured fractures, the linear flow stage and the pseudo boundary control flow stage. The increase of induced fracture number extends the duration of the complex linear flow stage and reduces the fluid seepage resistance. Therefore, the pressure curve of the early stage is lower. If the conductivity of induced fracture and fractured fracture is constant, the greater the conductivity is, the longer the duration of the bilinear flow regime is. When all fractured fractures are different region, the two end low permeability region along the wellbore weakens the "supply" stage. Therefore, the lower the permeability along the wellbore is, the higher the pressure curve at the early stage is. When all fractured fractures are in same area, the permeability change only affects the pressure curve shape after the radial flow stage. The lower the permeability of the outer area is, the higher the pressure curve after the early radial flow stage is. The practicability and accuracy of the model and method are demonstrated by the field example.