Experimental Determination of Friction Factors for Mist and Foam Drilling and Well Cleanout Operations

This work covers both theoretical and experimental analysis of frictional losses due to the presence of solids in vertical flow of solids-foam slurries. Rabinowitsh-Mooney generalized flow equations for time-independent fluids from the theoretical basis for the rheological analysis. Experimental work was done with an apparatus designed to simulate actual field conditions as closely as possible. The test section consists of an annulus with 4.0-in. casing and 1.5-in. tubing. The surface active agent used is an aniomic biodegradable foamer (ADOFOAM BF-1) and constitutes 1 percent of the liquid volume. Foam qualities and wall shear rates ranged from 0.64 to 0.99, and 100 to 1000 sec⁻¹, respectively. Semi-empirical equations for predicting friction factors due to solids are presented. Sandstone and limestone particles were used. Average particle size ranged from 0.025 to 0.11 in. and a total of 337 data points were used in the correlations. Data collection was carried out above solid saltation velocities under fully developed steady-state flow conditions. Results show that the friction factor of suspension can be treated as the sum of the friction factor due to the fluid and that due to the solids. For a constant foam Reynold’s number, the frictional losses due to the presence of solids increase as the solids mass flow rate (or solids content) increases. Solids friction factor was found to increase with increasing particles Froude number (gd_s/V_F²), density ratio (ρ_s/ρ_F), solids concentration, but decreases with increasing fluid Reynolds’ number.