Surface modified proppants used for porppant flowback control in hydraulic fracturing

Abstract

In order to solve the problem of proppant flowback in postfrac fracturing fluid flowback treatments and hydrocarbon productions, new heterocyclic polymer modified proppants were introduced. The most important characteristic of the modified proppants is self-aggregation in the water environment. Due to this special character, an evaluation method based on ultrasonic oscillation effect is developed to measure the aggregating strength of the proppants congeries, with which the optimal formula and the recommended dosage are determined. By virtue of the reaggregating property of the modified proppants, which is different from the one-time bonding effect of resin coated proppants, the fracture conductivity and the proppant flowback control ability are improved greatly. Experimental results show that with the dosage of 1.0% of the PFVP, the strength of the reaggregating column decreases by 54.6% after ten times of collapse and reaggregation, which is even big enough for proppant flowback control. The larger the dosage of PFVP is, the higher the strength of the reaggregating proppant column regains. Compared with untreated proppants and resin coated proppants, the maximum sand free flow rate of the modified proppants increases by 80.6% and 39.8%. The higher the closure stress is, the more obvious the proppants flowback control ability is. In addition, the formation fines adsorption property of the PFVP modified proppants endows the self-cleaning property of the flow channels in the fracture. The results provide a new alternative for proppant flowback control, especially in unconsolidated sandstone formation with high closure stress.