Cuttings transport with aqueous foam at intermediate-inclined wells

An experimental study of cuttings transport with foam at intermediate angles has been conducted in a full-scale low-pressure ambient-temperature (LPAT) flow loop at the U. of Tulsa. An anionic surfactant was used in these water-based foam tests at a concentration of 1 vol%. Air was used as the dispersed fluid. Tests were conducted to obtain flow curves for foams with 70 and 80% qualities in 2-, 3-, and 4-in. pipes. A simulator was developed to predict pressure, flow velocity, specific volume-expansion ratio, and foam quality along the wellbore, on the basis of the volume-equalized power-law model. Tests were conducted to determine the effects of inclination angle, foam quality, foam velocity, and rate of penetration (ROP) on cuttings transport. Results from this study show that the in-situ cuttings concentration ranged, according to the inclination angles, from 4.8 to 14.6% for 451, 14.3 to 22.3% for 55 degrees, and 8.5 to 25.7% for 65 degrees. It is shown in this study that the transport of cuttings (in terms of cuttings concentration) has a better performance with foams of low quality. For a given inclination angle and similar foam-flow conditions, increasing the ROP from 20 to 44 ft/hr can lead to an increase in the in-situ cuttings concentration of up to 7%. A new correlation for the ratio of the cuttings-bed area to the cross-sectional area of the annulus as a function of dimensionless numbers (A(r), N-Re, F-r, S-s, and theta) was developed and allows for potential practical applications. The differences between the calculated and measured values are within the range of 17%.