The Effects of Particle Size, Fluid Rheology, and Pipe Eccentricity on Cuttings Transport

Abstract

AbstractThis study was conducted to gain a more in-depth understanding of solids transport for coiled tubing workovers, cleanouts and drilling applications. Cuttings or particle transport in Coiled Tubing operations is a complex problem that is affected by numerous parameters. Predicting effective cuttings transport requires all of these parameters to be considered simultaneously. Tests were conducted to determine the effects of the following parameters:I) Different particle size, II) Fluid rheology, including water, gel, and multi-phase fluids, III) Pipe eccentricity, coiled tubing positioned on the low and high side of the wellbore.The effects of the different parameters were investigated in two different modes: the circulation mode, that involves the development of a cuttings bed or build-up of cuttings in the wellbore, and hole cleaning mode, which is cleaning out an existing cuttings bed. It will be shown that the results indicate: 1) for the tested particle size range (0.150 – 7 mm), cleaning efficiency is partly dependant upon the particle’s size, 2) with suitable agitation, a gelled fluid is more effective for cuttings transport than water in a highly deviated wellbore, 3) Pipe eccentricity has an effect on cuttings transport for different fluids and 4) for complete wellbore clean-up it requires many more hole volumes than previous ‘rules of thumb’ would indicate.