Terry Hemphill

Hole-Cleaning Capabilities of Water- and Oil-Based Drilling Fluids: A Comparative Experimental Study

Many laboratory studies evaluating the cuttings transport capabilities of water- and oil-based drilling fluids have been published, but few attempts have been made to investigate both fluid types under identical, controlled conditions. Those that considered both fluid types measured cuttings accumulation in the annulus and not fluid velocity. In this comparative study, the efficiency of water- and oil-based muds in cleaning the inclined annulus at varying fluid velocities was investigated. The results showed that, under equivalent rheological and flow-velocity profiles, water- and oil-based drilling fluids clean similarly. While fluid velocity is key to hole cleaning, other parameters, such as mud density and flow index n factors, can affect cuttings transport efficiency in certain hole angle ranges.