Polyacrylamide-based friction reducers (FRs) and high-viscosity friction reducers (HVFRs) are designed to reduce friction losses in tubulars and improve proppant placement. Low-cost anionic FRs are suitable, and are often the standard, in mild-salinity environments. However, to perform in high-salinity environments, anionic FRs require one of the following: 1) an increase in polymer activity/concentration/molecular weight, or 2) the introduction of sulfonated/cationic monomers. This study presents the screening process of commercial boosters used to improve the performance of low-cost conventional FRs and HVFRs.

Conducted at room temperature, as well as the various bottomhole temperature conditions encountered in the Permian, Bakken, Haynesville and Eagle Ford shale plays, the study is designed to investigate the boosters’ effects on the performance on FRs, whether these FRs are in liquid or dry form, by introducing different nonionic or charged surfactant species. The study presents impact on drag reduction, yield viscosity and viscosity at different sweeps (including the ultralow shear rates encountered in the fractures). Further, the study tests viscoelasticity and creep behavior; this is to determine if the friction-reduction effect is due to faster dispersion or to improved hydration due to changes to colloidal distribution.

Impact of FR boosters is limited by the makeup of the boosters, as well as the delivery form of the FRs or HVFRs. The study team observed that, when conventional anionic FRs are delivered in the invert emulsion form, proppant transport properties improve with the addition of specific nonionic- and/or cationic-based surfactants.

Unlike traditional methods used to predict the impact on the performance of FR boosters, this new testing methodology more effectively predicts the impact of small tweaks in the booster's molecular structure, which reduced pumping pressure in this study by approximately 500 psi.

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