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 FR that is applicable under essentially all-brine situations.This friction reducer,namely,FR-2 is developed through molecular design and process optimization.The contours of the macromolecules are tailored in such a manner that they incur minimized retention by the surrounding matrix and are insensitive to salinity variation.A complex reaction medium was chosen to render liquid dispersion of particles ranging from nano to submicron scale for rapid dissolution.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(dry & liquid emulsion)are compared with FR-2 regarding core damage,friction reduction under various brines(KCl,CaCl2 & FeCl3 at 100,000 ppm,respectively)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(time to reach 90%of max.friction reduction after injection).In contrast,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 wash 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 & gas production and to render peace of mind during fracking operations.