Abstract
Temporary plugging technology are widely used in unconventional exploitation, for it can produce more fracture thus to enhance oil recovery, however, it is still unclear how the plugging is formed and the diverters migrate in the hydraulic fracture. In this work, a self-developed visualization fracture system is set up. And the plugging mechanism of guar-based fracturing fluid with temporary plugging materials is visualized in a rough laboratory-scale fracture. Impacts of parameters on plugging process like particle concentration,fibre concentration, and fracture width are systematically investigated.Through a series of comparative experiments, it is found that the plugging process was triggered by fibre, they form nets to capture particles, then the nets with particles roll bigger and bigger like snowballs,while the nets can not capture particles will be broken in higher pressure. Comparative results indicate that the sealing effect of the same forum for wider fracture will be worse, replacing with the larger particles is more effective than increasing the amount of diverter; Increasing particles can increase sealing strength while increaing fibres can shorten the sealing formation time; Using 1% fiber only, the 3mm-wide fracture can be plugged but it cost much time and the sealing is not so firm. While using 1% particles only, a particle dump forms instead of a sealing layer. For field operation, it is suggested that (1) For wider fracture, use bigger particle is more effective than add more fibre and particles; (2) Particle should be added later than fibre; (3) To increase sealing pressure and enhance efficiency, the ratio of fibre and particles should be around 2:1.
