A Breaker-Free, Non-Damaging Friction Reducer for All-Brine Field Conditions

Acrylamide polymers are frequently used as friction reducers (FRs) in slick water fracturing. Although these FRs are effective at curtailing turbulent flow, the resultant formation damage is a major concern. This issue becomes worse when high-salinity water is encountered. Attempts are made to utilize breakers to reduce the extent of damage. However, the results are mostly subpar in nature. In this paper, we describe a breaker-free, non-damaging nano-composited friction reducer, namely FR-2, that is applicable under essentially all-brine situations. The extents of friction reduction and rates of hydration are characterized with flow loop. Formation damages are assessed with using synthetic quartz cores. Various conventional friction reducers are compared with FR-2 regarding core damage, friction reduction under various brines and rate of hydration. The results show that whereas these conventional FRs led to a core damage as high as 99.5%, that by FR-2 was essentially zero. On the other hand, although these conventional FRs perform well in terms of friction reduction in fresh water or even in KCl, their performances deteriorate substantially in the presence CaCl₂. Most strikingly, when FeCl₃ is present, the FRs in comparison lost their effects entirely. In contrast, FR-2 remains consistently robust in reducing friction regardless of the brines. FR-2 hydrates in 10–20 sec, whereas some of the tested FRs require longer than 2 min to achieve the same results. Field trials corroborate the effectiveness of using FR-2 for well clean out and hydraulic fracturing. To our best knowledge, this is the first report on a breaker-free, non-damaging friction reducer for slick water fracturing. The novelty also lies on the fact that the performance of this FR demonstrates independency upon brine variation. These aspects are expected to enhance oil and gas production and to render peace of mind during fracking operations.