During hydraulic fracturing treatments, fracturing fluid is pumped down the well in turbulent flow through commercially available rough iron pipes. Pipe roughness contributes largely to friction loss or friction pressure in turbulent flow. Methods have previously been presented to estimate friction loss of fracturing gels (non-Newtonian) in turbulent flow in smooth pipes, but not for rough pipes.

In this study the effects of pipe roughness on friction pressures of uncrosslinked as well as crosslinked fracturing gels are reported from flow data gathered in smooth and rough pipes. It is found that pipe roughness effects are very significant when estimating friction pressures of fracturing fluids. These effects are more pronounced with less viscous fluids than with more viscous fluids, and are also more pronounced at higher rates with both fluids. From the data gathered with fluids tested in this study, correlations to estimate friction pressures of fracturing gels in turbulent flow in rough pipes are also presented. Though not ideal, these correlations allow better estimates of friction pressures in rough tubular conductors than do existing methods.

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