Cuttings transport in horizontal and highly deviated wellbores is challenging because the fluid velocity in these wells has a reduced vertical component. Hole cleaning sweeps are applied to reduce cuttings accumulation in the wellbore. Field studies indicate that fiber-containing sweep fluids have been very effective in cleaning horizontal and highly deviated wells. Although the results of preliminary field studies are encouraging, very little is currently known about cuttings transport efficiency of fiber sweeps.
This article presents results of experimental investigations conducted to study hole cleaning performance of fiber sweeps. Flow loop experiments were performed in horizontal and inclined configurations using two test fluids: i) base fluid (0.47% Xanthan Gum); and ii) fiber sweep (0.47% Xanthan Gum with 0.04% synthetic fiber). Rheological properties of the test fluids were very similar. Experiments were conducted by eroding cuttings deposited in the test section at a constant flow rate and measuring the amount of cuttings removed by the base and sweep fluids. Results indicate that the fiber sweep has better hole cleaning capabilities than the base fluid in the horizontal configuration. When tests were conducted in an inclined configuration (68° from vertical), improvement in the hole cleaning capability of the fluid due to the addition of fiber is moderate. The experimental results and findings of this research are very useful for directional and extended-reach well drilling applications.