Friction Reducers as Water Management Aids in Hydraulic Fracturing

Abstract

Abstract Hydraulic fracturing has transformed the American energy industry, allowing unprecedented access to shale oil and gas deposits. However, fracturing's demand for water has raised concerns across the country, particularly in water-stressed regions like Oklahoma and Texas. Additionally, costs for disposing flowback and produced water have risen and regulations have tightened. Water management is becoming a crucial part of pressure pumping. Instead of paying to import fresh water and paying again to dispose of produced and flowback water, many operators are now seeking to blend fresh and flowback water, but this strategy has its own challenges. Flowback water can contain elevated levels of dissolved solids (particularly polyvalent cations), bacteria, and organics, which can impair conventional friction reducer performance. Additionally, chemicals used to remediate flowback water can potentially affect friction reducer performance. In order to aid water management efforts, Kemira has developed a friction reducer platform that shows superior performance in flowback and produced water with TDS concentrations as high as 236,000 ppm. These emulsion polyacrylamides (EPAMs) have molecular weights in the range of 20 – 40 million Daltons and are compatible with other additives such as scale inhibitors and biocides. Friction reduction measurements were performed using a laboratory-scale friction loop designed to simulate the turbulent flow conditions encountered during hydraulic fracturing. Flow rates of 30 gallons per minute were achieved in 0.5-in diameter tubing, resulting in Reynolds numbers of 150,000. The polymers provided friction reduction up to 65% in produced and flowback water, and maximum friction reduction was reached in 50 seconds or less in all cases. By comparison, conventional friction reducers dissolved in 120 seconds in high TDS waters and gave less than 20% friction reduction.