Research On Fracture Propagation Law Of Hydraulic Fracturing Under Pulsed Condition

The conventional hydraulic fracturing has been difficult to solve the problems such as high pressure of coal seam fracturing construction,single fracture shape after fracturing,and limited impact range.Therefore,the hydraulic fracturing technology under pulsed conditions is exploratively proposed.In this paper,the method of combining physical model experiment and numerical simulation is used to analyze the fracture shape and pressure curve after fracturing by changing the three variables of pulse displacement combination,pulse frequency and pulse series in the physical model experiment;The ABAQUS software was used to simulate the pulse fracturing process,the seepage stress coupling was used to simulate a three-dimensional reservoir,and the cohesive unit was used to describe the fracture propagation.The effect of different in-situ stress difference,fracturing fluid displacement combination and fracturing fluid viscosity on fracture propagation.The study found that: hydraulic fracturing under pulsed conditions can effectively reduce the initiation pressure of coal rock reservoirs;increasing the pulse frequency can generate micro-fractures,and the combination of pulse displacement can turn fractures and increase the number of pulses.The initiation stage has no obvious effect;numerical simulation results show that under different conditions of in-situ stress and fracturing fluid viscosity,the changes in fracture morphology and pore pressure still meet the traditional hydraulic fracture propagation rules.The research results provide guidance for the development of pulsed hydraulic fracturing technology in the future.