A study of cuttings transport at intermediate inclinations usingaerated fluid, to determine the amount of solids that exist inthe wellbore and minimum flow requirements for ‘clean-hole’condition is presented. The experimental program includedover 300 tests, performed with a large-scale facility (flow loop100-ft in length, with 8" OD casing and 4.5" OD drillpipe).The angles of test section inclination were 30o, 45o and 60ofrom vertical. Four pipe rotational speeds (0, 40, 80, and 110rpm) were used for different liquid and gas flow ratecombinations. New correlations were found to estimate therequired critical gas flow rates for hole cleaning at specifiedliquid flow rate and drill pipe rotation combinations, and topredict volumetric cuttings concentration as a function of airand water flow rate, drill pipe rotational speed andinclination angle.
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