Anionic polyacrylamide copolymer friction (or drag) reducers are commonly used in various well stimulation jobs. The effectiveness of friction reduction polymers strongly depends on the compatibility between friction reducing polymers and stimulation liquid to which they are added. Performance of friction reducers can be strongly influenced by the presence of salts, very high or very low pH, or other typical process additives, such as biocides, corrosion and scale inhibitors, hydrogen sulfide (H2S) scavangers, etc. Since most friction reducers are emulsion polymers, an important issue related to their performance is their ability to invert effectively and efficiently upon the addition to the stimulation fluid. A fast enough rate of inversion is especially important, since it determines both the effective onset of optimal friction reduction and its magnitude. Higher friction reduction achieved at the very beginning of a well stimulation will decrease the pumping pressure on a job. We hereby describe novel, fast-inverting friction reducers suitable for effective use in brines and compatible with various additives, such as biocides, clay control agents, and scale inhibitors.

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