Simulation of cutting transport process during foam drilling by implementation of computational fluid dynamics approach

The ability of drilling fluid to transport cuttings is an important factor to be considered in drilling operation. Countless problems such as stuck pipe and wellbore instability might happen if the appropriate fluid is not used, and it can be even more challenging when drilling is directional or horizontal. Among all drilling fluids, foam is well-known for its superior capability in cutting transport and being convenient for underbalanced drilling. The quality of foam and its transport capability is sensitive to pressure and temperature variation in the wellbore due to its dominative gaseous phase. In this paper, the cutting transport process by foam is simulated by implementing Computational Fluid Dynamics (CFD) approach in COMSOL Multiphysics software. During the simulations conducted in this study, the quality of foam is considered to vary along the wellbore due to pressure drop, which is quite important and effective in long wellbores, in particular. Results are validated in concentric and eccentric modes, indicating that the quality and velocity of foam mitigate the cuttings concentration and increase the pressure drop. Moreover, results show that temperature increment leads to more depositions and less pressure drop while higher test pressures and drill pipe rotation do the vice versa, resulting in less concentration of cuttings (especially in higher cutting sizes) and more pressure drop. Thus, the results confirm the proficiency of CFD approach in simulating the cutting transport process. •The variation of foam quality along the wellbore and its rheological behavior and transport mechanisms are simulated.•Effects of axial velocity and fluid temperature on the behavior of foam, as a non-newtonian fluid are discussed.•Rotation of drill-string and its effects on the rheological behavior of foam and its transport process are discussed.•Effect of cuttings size on the deposited bed profile and the quality of hole-cleaning is investigated.