Returning to the Lab

Shale gas resources have been aggressively sought out for the past few years. The resurfacing and evolution of hydraulic fracturing technology has been triggered by the need to fracture shale-gas in a massive scale. Although the basic ideas for fracturing are similar between conventional fracturing for formation damage mitigation and slickwater fracturing for shale gas, the fluids’ characteristics are much different.Thus, better understanding of slickwater slurry behavior is critical to ensure a successful fracturing job, effective both engineering-wise and economically. This paper presents the results of related studies in the behavior of slickwater slurries. The experiments comprise of a study on fluids’ rheology with a Brookfield Viscometer, and also the observation of the proppant slurries in flowing conditions. The polymers used to make the slickwater slurries composed of polyacrylamides manufactured domestically in Korea. As for proppant, Carboceramics proppant of 20/40 US Mesh and 40/70 US Mesh were used. A parallel-plate setup was designed to model a simplified fracture, and later used to analyze the flow of proppant slurries with different friction reducers, proppant sizes, and proppant concentrations. The slurries were made according to typical designs previously applied in the field. Observation results showed that proppant settling in slickwater does not resemble proppant settling in viscosified gel solutions and that the horizontal transport of proppant relies on the building of proppant beds. Larger proppants tend to quickly form a ‘dune’ near the entrance of the fracture model until it reached an equilibrium height. The flow velocity of the fluids increased over the dune and increased the transport capability of smaller-sized proppant deeper into the fracture. Previous authors have studied that by modifying pumping schedules based on these results, gas production remarkably increased. In light of this, further plans in studying the modification pumping schedules based on this study are underway.