Transient thermal-nonequilibrium model for prediction of cutting removal during drilling of directional wells

Transient thermal-nonequilibrium mathematical model for prediction of cutting removal during drilling of directional wells is presented in current paper. The model is based on two-layer model that takes into account the cutting in the fluid flow and motionless cutting substrate. The paper gives the relationships that allow calculating the mass exchange between the substrate and the cutting in the stream, the interphase friction and heat transfer between cutting and fluid flow and fluid flow with walls of the well. Options for simulation of Newtonian and non-Newtonian fluid are implemented into the model. It is assumed that the fluid moves in the annular channel formed by the well walls and the drill string. The presence of eccentricity in the channel is taken into account. To simulate the motion and heat transfer, a system of mass, momentum and energy equations is solved. Numerical method is based on control volume approach. There are some calculation results that demonstrate ability of the model to simulate displacement of the cutting from the well.