Sensitivity analysis of hole cleaning parameters in directional wells

In this study, 600 tests were conducted and a new computer program was developed for the prediction of cuttings transport in the multiphase system (gas+liquid+cuttings). The sensitivity of cuttings bed height with, respect to, liquid/gas volume flow, rate ratio, in-situ liquid velocity, rate of penetration (ROP), inclination angle, and circulation fluid properties was conducted. The hole-cleaning time with both circulation mode and wiper trip is also discussed. The results from the sensitivity analysis presented in this paper indicate, first, that the fraction of the circulation liquid has a significant impact on the cuttings transport in underbalanced drilling with gasified fluids; second, that among different variables, the in-situ liquid velocity is the most important variable for cuttings transport; and, finally, the hole-cleaning time decreases nonlinearly with increasing fluid circulation rate.