Hydraulic fracturing is often performed using resin-coated proppants to minimize proppant flowback during hydrocarbon production, whether the resin is precoated or coated on-the-fly as the treatment is pumped. Resin-fracturing fluid interaction can have a negative effect on fluid stability or resin consolidation, or both. This paper examines the effects of resin-fluid interactions on fluid stability, proppant consolidation strength, and strategies to mitigate the effects.
Components of resins can change the fracturing fluid stability by interacting with crosslinker or breaker, or by changing the fluid pH. To offset the effect of a resin, the breaker/crosslinker/buffer concentration should be tuned while pumping resin-coated proppant. Similarly, resin-fluid interaction can decrease consolidation strength by disturbing resin-curing kinetics or reducing grain-to-grain contact, which can increase the possibility of proppant flowback during production. The influence of resins on fracturing fluid stability was evaluated by conducting rheology testing. The effect of fracturing fluids on the consolidation strength of resin was evaluated by comparing unconfined compressive strength (UCS) of proppant packs.
The stability of zirconate and borate crosslinked guar fluids, when treated with coated on the fly liquid resin-coated proppant (LRCP), was lower than non-treated fluids at 260°F as a result of breaker activation by the resin components. The desired fluid stability was attained by lowering breaker concentration in liquid resin-treated fluid. During another round of testing, a second type of LRCP, based on different chemical functionality, increased the stability of synthetic polymer fluid at 400°F. Likewise, a rise in fluid stability was observed when guar fluid was treated with resin pre-coated proppant (RCP) at 200 and 250°F. The improved fluid stability is associated with reduction in active breaker concentration in the presence of furan resin and RCP. The UCS value of the proppant pack prepared from fracturing fluid-treated RCP was ~16 to 45% lower than the proppant pack without this fluid treatment. Additionally, the UCS value of proppant pack prepared using fracturing fluid-treated LRCP decreased by ~30%. However, the measured UCS value of LRCP pack with fracturing fluid exposure was higher than the RCP pack measured value even without exposure to this fluid.
Incorporating LRCP instead of using RCP during fracturing operations could address the proppant flowback issue and possibly result in higher conductivity of propped fractures. It could help ensure economic production rates and prevent costs associated wellbore cleanup, downhole tool damage, erosion and damage to the tubular, chokes, valves and separators, and refracturing of the well. Ultimately, it could help maintain a lower cost per barrel of oil equivalent (BOE).