Modeling of dynamic cuttings transportation during drilling of oil and gas wells by combining 2D CFD and 1D discretization approach

This paper presents an approach that combines a two-dimensional (2D) computational fluid dynamics (CFD) and one-dimensional (1D) continuous model for cuttings transport simulation during drilling of oil and gas wells. The 2D CFD simulates the flow profile and the suspended cuttings concentration profile in the cross section of the wellbore and the 1D continuous model simulates the cuttings transportation in the axial direction of the wellbore. Different cuttings sizes are considered in the model by using a new proposed superposition method. Experimental tests conducted on a 203×114×25mm3 flow loop are used to validate the model from three different perspectives: the single-phase flow pressure drop, the steady-state cuttings bed height, and the transient pressure changes. Compared to layer models, the new approach is able to catch accurate flow details in the narrow flow region and overcome the shortcoming of traditional models that underpredict bed height under high flow rate conditions. The computational time increases by the order of 104∼105 from the level of millisecond to seconds but is still within the acceptable range for engineering applications, and the model provides close to three-dimensional (3D) accuracy at a much shorter central processing unit (CPU) time compared to 3D CFD models. Copyright © 2020 Society of Petroleum Engineers.