A New Insight into Friction Reducer Evaluation for Slickwater Unconventional Fracturing

Abstract Slickwater fracturing has increased over the past couple of decades in the development of shale and tight formations. Friction reducer is the main component of slickwater, which reduces drag in the tubular. For successful and economical slickwater hybrid fracturing treatment, selection and optimization of friction reducers play a key role. This paper presents a new insight into optimizing friction reducer using helical coiled flow loop at high-pressure, high-temperature (HPHT) conditions. Usually, friction pressure is estimated by pumping slickwater fracturing fluid through a straight tube and measuring differential pressure across the tube. This required pilot-scale laboratory setup and testing at HPHT bit challenging. In this paper, small sized equipment, helical coiled flow loop was utilized to estimate friction pressure of slickwater fracturing fluid. Friction reducers can be rigorously tested for degradation because secondary flow resulting from centrifugal forces can be caused by the coil curvature. Correlations for Darcy friction factor as a function of Reynolds number has been developed for helical coiled fluid loop in both laminar and turbulent flow regime. The present study evaluates different friction reducers in ¼ in. ID smooth helical coiled flow loop. The correlations developed for Darcy friction factor was well validated for water with data available from literature. Polyacrylamide based friction reducers with different concentration were used in this study. The friction pressure, with and without friction reducers, was compared at different flow rates. Percent drag reduction at different polymer concentration was also evalauted using helical coild flow loop. Thermal degradation of friction reducers was evaluated by varying temperature up to 300°F. New correlations to measure friction losses using helical coiled flow regimes are presented in this paper. Reduced drag reduction due to secondary flow resulting from centrifugal forces in helical coil can judge friction reducer more thoroughly then conventionally used straight tube flow loop.