Experimental study on improving complexity of hydraulic fracture geometry in reservoirs with large horizontal stress difference

Aimed at solving the problem on creating a complex hydraulic fracture geometry at reservoirs with large horizontal stress difference and few natural fractures. This paper designs a series laboratory experiments to investigate the laws of the hydraulic fracture initiating and propagating at inclined wellbores under a large horizontal stress difference condition. A tri-axial fracturing apparatus and an alternating injection device was utilized in the experiment, with which we can switch different fracturing fluids and keep continuous injection. Influence factors including wellbore deviation, perforation and the temporary blocking agent on fracture morphology is studied. The experiment results show that, it can still form a complex fracture geometry with a curved fracture surface by perforation or using temporary blocking agents, and the fracturing turning point is near the end of the perforation. Adding the blocking agent into fracturing fluid can help to increase the fracture net pressure by 16Mpa and create new fractures. The blocking agent with particle size of 200 mesh and mass fraction of 5% can achieve an effective plugging, bearing the pressure as large as 80MPa. This study can provide a feasible method to help improving the hydraulic fracture geometry and solving the fracturing problem.