Fracture Mouth Plugging Pattern During Temporary Plugging and Diverting Fracturing : An Experimental Study

Fracture mouth temporary plugging and diverting fracturing (TPDF) technology refers to the use of self-degradable diverters to plug the previously created fractures, the wellbore pressure can be enhanced and the injection fluids can be diverted into the under-stimulated zone, thus the overall stimulation effects along the wellbore can be improved. Due to the influence of downhole temperature and pressure conditions and the morphology at the fracture mouth, the experimental study of slot plugging test at room temperature cannot effectively guide the field operation of the fracture mouth TPDF, and the success rate can be significantly influenced. In this work, a high-pressure evaluation system for fracture mouth temporary plugging is designed, the effects of temperature and real fracture morphology can be considered effectively. The key factors and their influencing pattern on fracture mouth plugging are systematically investigated. Moreover, the optimal temporary plugging condition and the key factors affecting the plugging effect were determined by orthogonal experiments. The results show that the diverter bridging speed at 150 °C increases by 33% compared with that at room temperature, and the corresponding diverter dosage decreases by 34%. If the diverter concentration is too high, the diverter bridging speed will be reduced and the diverter dosage will be increased. The higher the fluid injection rate and the carrier fluid viscosity, the faster the diverter bridging speed (DBS), and the less the diverter dosage. The factors influencing the diverter dosage rank (from strong to weak): viscosity of carrying fluid, temperature, fluid injection speed, the concentration of 1 mm particulate shaped diverter (PSD), and concentration of 3 mm particulate shaped diverter (PSD)