Simulation Study on the Range of Diversion in Targeted Fracturing of Prefabricated Fractures in the Tahe Oilfield

Oil and gas resources of the ultra-deep carbonate reservoirs in the Tahe Oilfield occur mainly in natural fractures and cavities, and the application of a targeted fracturing technology for prefabricated fractures can control the fracture diversion and improve oil and gas production. By utilizing the corrected resistance reduction ratio method to calculate string resistance, combining the unstable seepage theory to calculate pressure change in a fracture, and applying the displacement discontinuity method to calculate fracture propagation and diversion, it is able to establish the integrated model of fracture propagation. Through computational analysis of parameters such as the fracture propagation direction/angle and extension length of prefabricated fracture-bearing targeted fracturing, and correlating the pumping parameters and the diverting distance of hydraulic fracture, the accuracy and validity of this model are validated by virtue of finite element method and physical simulation experiments. The study results showed that the parameters of fracturing fluid viscosity, prefabricated fracture angle, in-situ stress difference and formation rock elastic modulus are negatively correlated with the diverting distance of hydraulic fracture. In this case, the length of prefabricated fracture is positively correlated with the diverting distance; the preferable pumping flow rate shall be adopted to achieve the optimal diverting distance. The simulation results of targeted fracturing prefabricated fracture diverting technology provided the theoretical guidance and data support for the efficient development of ultra-deep carbonate fracture and cavity reservoirs in the Tahe Oilfield.