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Sotoudeh, Fatemeh (Sophia)

University of British Columbia

This thesis investigates the fluid mechanics of displacement flows in eccentric horizontal and inclined annuli, focusing on applications in well cementing operations in the oil and gas industry. These annular geometries, particularly eccentric ones, pose challenges during fluid displacement, leading to residual mud channels that can compromise well integrity. Understanding the interactions between eccentricity, fluid properties, flow rates, and casing rotation is essential to improving displacement efficiency and cementing reliability. Key parameters studied include fluid viscosity, density contrasts, eccentricity, annular inclination, and casing rotation. In highly eccentric annuli, the casing settles at the bottom, creating a narrow gap where residual mud can remain trapped. Casing rotation is explored as a solution, inducing helical fluid movement that helps lift the residual mud and improve displacement. However, rotation also introduces flow instabilities and local mixing, complicating the flow dynamics. 3D Computational Fluid Dynamics (CFD) simulations are conducted to analyze velocity and concentration profiles, offering insights difficult to capture experimentally. These simulations are validated against experimental data for accuracy. Results show that higher casing rotational speeds significantly enhance displacement efficiency by promoting azimuthal dispersion and reducing mud channel formation. Rotation induces secondary flows, leading to more uniform displacement. Interestingly, instabilities on the inner annulus wall were observed, a phenomenon not noted in previous experiments, with potential implications for cementing designs. The study also examines the nonlinear effects of buoyancy, viscosity, and eccentricity on displacement efficiency, visualized through contour plots. While higher rotational speeds generally improve displacement, they also increase the risk of localized mixing and flow instabilities, requiring careful management. In conclusion, this research enhances the understanding of displacement flows in eccentric annuli, highlighting the benefits and risks of casing rotation. The findings offer practical strategies for optimizing cementing processes, contributing to well integrity and performance in the oil and gas industry.

Text

2024-10-21

Attribution-NonCommercial-NoDerivatives 4.0 International

http://hdl.handle.net/2429/89469

Mechanical Engineering

University of British Columbia

UBCV

http://creativecommons.org/licenses/by-nc-nd/4.0/