Session: 11-02-01 Well Drilling Fluids and Hydraulics-1

Submission Number: 176973

Convective Heat Transfer in Rotating and Eccentric Annuli for Drilling Applications: A CFD Based Parametric Study 

Effective thermal management in drilling operations relies on accurate modelling of heat transfer along the circulation path, from the surface to the bit inside the drill string and back again through the annular channel. Heat transfer inside the drill string can generally be modelled accurately using well-established correlations for Nusselt numbers in pipe flow. However, determining the convective heat transfer coefficients in the annular return is considerably more challenging in drilling-relevant conditions. Eccentricity between the drill string and the wellbore, inner-pipe rotation and non-Newtonian rheology all distort the velocity and thermal fields.

This study investigates convective heat transfer in the annular sections of wellbore hydraulic systems. The aim is to quantify the Nusselt number and explore how it depends on operational and fluid parameters. The analysis focuses exclusively on the fluid domain and excludes heat conduction in solid boundaries. A modified version of the buoyantFoam solver in OpenFOAM has been developed to incorporate Herschel–Bulkley rheology. Furthermore, a custom function object has been developed to evaluate the heat transfer coefficient based on the difference between wall and bulk fluid temperatures, enabling consistent and automated post-processing. Simulations and validation efforts are currently limited to Newtonian and power-law fluids. Key fluid and geometric parameters, including density, viscosity, thermal conductivity, heat capacity, diameter ratio and eccentricity, are scaled to ensure broader applicability.

The study concentrates on Reynolds and Taylor numbers within ranges that are relevant to drilling operations (Re up to 10⁴ and Ta up to 10⁷). Laminar flow simulations have been validated against analytical solutions for concentric annuli with varying diameter ratios, demonstrating excellent agreement. For turbulent flows, only Newtonian fluids have been considered thus far, and the results are consistent with available experimental data.

Trend analysis has been conducted to identify the influence of key parameters on the Nusselt number. Visualizations such as contour maps and velocity profiles highlight the effects of eccentricity, rotation and flow behavior index. Although correlation development is planned for future stages, the current results provide a solid foundation for understanding convective heat transfer in drilling annuli.

Presenting Author: Roland May Baker Hughes Company

Presenting Author Biography: Roland May is a Principal Engineer specializing in fluid mechanics at the Baker Hughes Celle Technology Center, Germany. He earned his Diplom-Ingenieur degree in Mechanical Engineering (equivalent to a Master of Science) from the Karlsruhe Institute of Technology in Germany. His research interests include wellbore hydraulics, computational fluid dynamics (CFD), non-Newtonian fluid behavior, turbulent flows, and engineering thermodynamics.

Authors:

Roger Aragall Baker Hughes Company
Alexander Starostin Baker Hughes Company
Roland May Baker Hughes Company