Investigation: Cutting Transport Mechanism in Inclined Well Section under Pulsed Drilling Fluid Action

Abstract

Due to gravity, drilling cuttings are easily accumulated in an inclined well section, ultimately forming a cuttings bed, which places the drill pipe under strong friction torque. In severe cases, this can cause dragging, stuck drills, and broken drill tools. Because conventional drilling fluids are difficult to prevent the formation of cuttings in inclined well sections, a method of carrying cuttings with the pulsed drilling fluid to improve wellbore cleanness is proposed. Experiments and numerical simulations are conducted to investigate the effects of cuttings bed transport velocity, cuttings size, cuttings height, drill pipe rotation speed, cuttings bed mass, and roughness height. The optimal pulse parameters are determined per their respective impact on cuttings transport concerning varied periods, amplitudes, and duty cycles of the pulsed drilling fluid. Compared to cuttings transport under the conventional drilling fluid flow rate, the pulsed drilling fluid produces the turbulent dissipation rate, increases cuttings transport velocity, and thus improves the wellbore clearance rate.

Flaky cuttings bed distribution model in a shale gas horizontal well based on experiment and numerical simulation

“…Liquid flow characteristics and cuttings characteristics are the two core factors that affect the migration of cuttings. Different process parameters during the construction process, such as annulus size, eccentricity, drilling fluid displacement, drill pipe rotation speed, rheological mode, angle of inclination, and performance of the drilling fluid, mainly affect the flow characteristics of the annulus fluid, while the size, density, and shape of drill cuttings mainly affect its force and movement in the drilling fluid (Cho et al, 2001;Duan et al, 2008;Ford et al, 1990;Gulraiz & Gray, 2021;Han et al, 2010;Huque et al, 2020;Ozbayoglu et al, 2008;Song et al, 2017;Zhang et al, 2015;Zhu et al, 2021).…”