Effect of salt on the performance of drag reducers in slickwater fracturing fluids

The results revealed that the anionic FR-B performs better than the anionic FR-A in fresh water. The percent friction reduction of FR-B and FR-A at 0.478 g/L (4 pptg) in fresh water were about 60% and 40%, respectively. In addition, the performance of FR-B is less sensitive to salts than that of FR-A. Therefore, It is recommended to add 0.478 g/L (4-pptg) of FR-B directly into the flowback, which has the total dissolved solid values of 100000 mg/L or less without the need of pretreatment to achieve the percent friction reduction of 40% or higher. Cationic FR-C performed the best when compared with anionic FR-A and FRB at high salinity, e.g. 200000-mg/L total dissolved solid. Under the testing conditions, a conservative conclusion may be drawn that cationic FRs may perform better with the presence of salts than that of anionic FRs.