Dissertations and Theses
Date of Award
2025
Document Type
Dissertation
Department
Mechanical Engineering
First Advisor
Masahiro Kawaji
Keywords
Particle Settling, Drilling Fluids, Taylor-Couette Cell, Particle Image Velocimetry (PIV), Manual Particle Tracking (MPT)
Abstract
This doctoral dissertation investigates heavy particle sedimentation in Newtonian and non-Newtonian fluids, aiming to understand their behavior in Drilling Fluid (DF) systems used in oil and gas industry, where such phenomenon can lead to operational issues such as lost circulation, well control problems, and even blowouts. To simulate DF dynamics under operational conditions, this study utilizes a Taylor-Couette (TC) cell, which consists of a rotating inner cylinder and a stationary outer cylinder separated by a 9.0 mm annular gap. The TC cell allows for the investigation of the sedimentation behavior of spherical particles within both Newtonian fluids (deionized water and mineral oil) and non-Newtonian fluids (carboxymethyl cellulose or CMC and Carbomer solutions). The non-Newtonian fluids (CMC and Carbomer) are used as a base model for real DF to observe the behavior of particle sedimentation under shear conditions in a controlled environment.
Particle Image Velocimetry (PIV) and Manual Particle Tracking (MPT) are employed to assess how rotational speeds and particle sizes influence the settling dynamics of heavy particles. The primary objective is to understand the influences of rotational speed, particle diameter and density on particle dynamics, providing insights relevant to DF applications. Experiments were conducted with particles ranging from 1.0 to 4.0 mm in diameter and densities between 1.2 and 3.95 g/cm³, at rotational speeds up to 200 revolutions per minute (rev/min).
The rheological analysis revealed that both CMC and Carbomer exhibit pronounced shear-thinning behavior, with viscosity decreasing as shear rate increases. Carbomer was found to be a superior model fluid compared to CMC, as it more closely mimics the rheological properties of the reference DF, adhering to a Herschel-Bulkley model which includes yield stress behavior, unlike the Power Law fluid model followed by CMC.
Experimental results demonstrated that rotational speed and particle diameter and density influence the particle settling velocity and horizontal velocity in both CMC and Carbomer. Increased rotational speeds led to faster settling due to the shear-thinning nature of the fluid, while larger and heavier particles exhibited higher settling and horizontal velocities due to a combination of increased mass and the ability to induce higher local shear rates, further reducing the effective viscosity. Theoretical predictions based on a simplified drag coefficient model aligned well with the experimental settling velocities in Carbomer. However, for the CMC solution, the predictions did not align well with the experimental results, possibly due to a combination of factors such as radial particle migration, wall effects, and the limitations of applying a simplified drag model to a power-law fluid under shear conditions.
While Carbomer and CMC serve as valuable model fluids for understanding particle sedimentation in complex fluids, it's crucial to acknowledge their limitations in fully representing the particle motion in actual DF. Real DFs, which are suspensions of clay and other heavy particles like barite with a density of 4.2 g/cm3, often exhibit higher yield stresses and distinct shear-thinning profiles compared to the model fluids used. This work investigated the settling of five different materials, including alumina (density of 3.9 g/cm³), which closely approximates the density of barite, and glass (density of 2.5 g/cm³), which is similar to the density of typical cuttings. Additionally, the particles used in this work were much larger in size than the heavy particles in DFs but had sizes comparable to those of cuttings encountered during drilling operations. Nevertheless, this study provides valuable insights into the relationship between particle properties, fluid rheology, and flow conditions, contributing to a better understanding of particle settling in shear-thinning fluids and offering potential implications for optimizing DF design and enhancing drilling efficiency.
Recommended Citation
Velez Mendoza, Andres F., "Experimental and Analytical Investigation of Particle Dynamics in Newtonian and non-Newtonian Fluids in a Taylor-Couette Cell" (2025). CUNY Academic Works.
https://academicworks.cuny.edu/cc_etds_theses/1284
