Slickwater Proppant Transport in Hydraulic Fractures: New Experimental Findings and Scalable Correlation

Slickwater hydraulic fracturing is an important technology that has enabled the oil and gas industry to economically develop enormous unconventional resources. Despite its great success, this technology faces challenges, especially with proppant transport in complex fractures. Very limited work exists in the literature regarding slickwater proppant flow in subsidiary fractures or predictive correlations to estimate settled proppant-dune heights. This paper provides a scalable correlation to predict dune height across a wide range of flow rates and proppant concentrations in the primary fracture. A unique feature of this correlation is its inclusion of the friction effect; roughness was introduced to the fracture-slot walls. A 30/70-mesh brown sand was used to conduct the slot-flow experiments and build the correlation. This paper also spotlights the proppant-transport mechanism during proppant-dune development in the primary fracture. Understanding this mechanism reveals key information regarding the horizontal and vertical settled-proppant-size distribution. In addition, experimental results are presented to answer the debatable question of whether slickwater can transport proppant into tertiary fractures. In fact, the data show that proppant in slickwater is not only capable of "turning the comer" but also developing high dune levels exceeding 97% of the tertiary fracture-slot heights.