Abstract
An accurate prediction of the settling velocities of drill cuttings is essential in effectively designing, running, and optimizing drilling operations. If there is no reliable process for modelling the drag coefficient, the settling velocity cannot be obtained. In most current literature, particles are assumed to be spherical, which can be easily modelled. However, this assumption may lead to inaccurate results for other irregular particle shapes. This paper studies the transport behavior of irregular particles by modelling these shapes as variants of a bow shape, with a numerical simulation approach for their drag coefficients. The drilling fluid around the particle is water (Newtonian). The drag coefficients of the non-spherical particle (grouped into three sub-shapes) were modelled. In addition, the inlet velocity of the fluid is varied to show the effects on the shape drag coefficients. The results of the simulations were compared to experimental results carried out by other researchers. It was observed that as the particles became less streamlined, their drag coefficient increased. A sensitivity analysis was carried out to investigate the effects of fluid properties on the drag coefficient. The results were consistent and logical. The results showed that Computational Fluid Dynamics analysis provided a reliable estimation of the drag coefficient, which can help optimize the transport of drill cuttings during drilling operations.
Highlights
The effective removal of drill cuttings from a wellbore is indispensable, and the proper hole cleaning ensures the safety of drilling operations
The results of the drag coefficient predicted by the proposed model were compared to results from previous works
The relationship between drag coefficient and inlet velocity for the three study model shapes is discussed below. This discussion covers a sensitivity analysis that shows the effect of fluid properties on the drag coefficient
Summary
Publisher’s Note: MDPI stays neutral with regard to jurisdictional claims in published maps and institutional affiliations. In calculating the settling velocity of a particle, it is important to determine the relationship between the drag coefficient and the Reynolds number. Equation (3) shows the relationship between the drag coefficient and Reynolds number for a spherical particle [13]: CD =. [4] discussed the CFD modelling of drill cuttings, they studied the transport velocities of spherical and nonspherical particles. Their approach was to simulate the transport velocity with sphericity and not drag coefficient. An understanding and an accurate prediction of the drag coefficient of drill cuttings can help optimize drilling drilling operations In this In study, a numerical solution with with is proposed to to investigate settling irregular-shaped particlesininNewtonian.
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