Bed load proppant transport during slickwater hydraulic fracturing: Insights from comparisons between published laboratory data and correlations for sediment and pipeline slurry transport

Bed load transport is the movement of particles along the top of a bed through rolling, saltation, and suspension created by turbulent lift above the bed surface. Based on experimental work, early investigators suggested that bed load transport may be an important mechanism during field scale hydraulic fracturing. However, later studies suggested that bed load transport is much more important in the laboratory than at field scale because the rate of bed load transport does not scale with fracture height. In recent years, there has been a resurgence of interest in the idea that bed load transport is significant at the field scale. Patankar et al. (2002) and Wang et al. (2003) presented new laboratory scale experiments on bed load proppant transport and proposed correlations to match the data. The correlations have subsequently been applied directly in field scale hydraulic fracturing simulators and have been used to design completion strategies and select proppants. This paper reviews correlations for sediment and slurry transport and provides a reanalysis of the laboratory results from Patankar et al. (2002). The analysis finds that the experiments can be well-described using classical correlations for sediment and slurry flow. The correlations are applied without adjusting any free parameters to fit the data. The analysis suggests that the total amount of proppant that can be transported in bed load transport in laboratory experiments is roughly similar to the amount transported at field scale. Because much greater volumes of proppant are injected at the field scale, the implication is that bed load transport is negligible in the great majority of field scale hydraulic fracturing treatments.