Abstract:
To solve the problems of fracture conductivity decline and downhole sand plugging caused by proppant backflow after hydraulic fracturing, a novel temperature-sensitive self-bonding proppant was developed by coating 20/40 mesh quartz sand with a temperature-sensitive polymer synthesized from bisphenol A and epichlorohydrin. Its temperature-sensitive activation, cohesion, breakage resistance, backflow control, conductivity, and resistance to formation fluids and foreign fluids were systematically evaluated, and field tests were carried out in the Liaohe Oilfield. The results show that the self-bonding proppant can be activated and agglomerate at 50 ℃, with a maximum applicable reservoir temperature of 120 ℃. Under simulated near-wellbore void conditions, its critical sand-production flow rate is up to 50 times that of quartz sand. Under closure pressures of 21~52 MPa, its conductivity reaches 51.8%~90.6% of that of quartz sand, it has good compatibility with guar-gel fracturing fluid and slickwater, and it maintains an intact sand-column morphology after long-term immersion in formation water, crude oil, acid and alkali solutions. A total of 10 well-times of field tests in the Liaohe Oilfield, using a 3:1 mixture of self-bonding proppant and quartz sand as tail-in sealing, reduced proppant backflow by more than 60% during the flowback stage and increased the pump-check interval from 178 d to 568 d. The study indicates that the novel temperature-sensitive self-bonding proppant can effectively control proppant backflow after fracturing, providing a new technical approach for fracturing sand control in unconsolidated sandstone and low-permeability reservoirs.