One of the main challenges in the reuse of flowback and produced water in slickwater hydraulic fracturing is the compatibility between additives and high total dissolved solids (TDS) concentrations, which are the most difficult contaminants to remove. Typical polyacrylamide friction reducers show reduced effectiveness in water with high ionic content, so water must either be treated or diluted with freshwater to reduce salt content before reuse.

The case for directly reusing produced water with high salt content is presented in this research. The first part of the study ascertains the effectiveness of various friction reducers in brines. While typical polyacrylamide friction reducers lose their efficacy at high salt concentrations, we have identified other polymers that are generally resistant to changes in salt concentration. The second part of the research assesses not only the effect of pumping high-TDS water into a formation, but also the impacts of salt-tolerant friction reducers on shale stability and fracture conductivity. Shale compatibility experiments determined that injecting water with a higher salinity into a water-sensitive formation can benefit shale stability. In addition, the friction reducing agents were shown to have secondary stabilizing effects on shale.