Drag reduction characteristics of trimethylolethane hydrate slurries treated with surfactants

Drag reduction characteristics of trimethylolethane hydrate slurries treated with surfactants have been investigated. The effects of the surfactant concentration and hydrate fraction of the slurry on drag reduction behaviors were focused on in this paper. The friction coefficient in a pipe flow of hydrate slurries treated with surfactants and the relaxation time of trimethylolethane solution with surfactants were measured. From the results, it was found that the effective drag reduction appears in the cases of high surfactant concentration even in cases of high hydrate fraction. This behavior was supported by the viscosity shear-thickening occurrence reported in the previous study. However, the effective drag reduction disappears in the cases of low surfactant concentration in spite of the shear-thickening occurrence. On this discrepancy, the relaxation time of the solution was measured. It is found that the critical concentration determined from the relaxation time disappearance well corresponds to the limitation of effective drag reduction occurrence. (C) 2008 Elsevier Ltd and IIR. All rights reserved.