Drill string rotation has been the target of several studies involving its influence on the suspension of drilled cuttings deposited in the bottom part of highly inclined and horizontal wells. Since some studies found in the literature exhibit divergence over the effect of the drill string rotation on the suspension of cuttings, this project is intended to quantify the capacity for suspension of particles from the cuttings bed for different fluids and different sedimentation heights, in cylindrical horizontal wells. Quantifying the suspended mass in the annular geometry of the well was modeled after an experimental set-up on the physical problem, which allows tangential flow in the annular space. Flow visualization and image processing techniques support the study.

We analyze the use of water solutions of Xanthan Gum (XG) for drag reduction (DR) in annular spaces. We provide a direct quantitative comparison between the DR in an annulus and that in straight tubes. We can fairly compare the data from the two geometries by using the general definition of the Reynolds number, which is independent of the geometry. With such a definition, the product of the friction factor by Re is a constant in laminar flows. Moreover, the friction factor for a turbulent flow of Newtonian fluids in an annulus fits Colebrook's correlation. Our main results show that the DR is more pronounced in annular pipes than tubes. We believe this is due to the relative increase of the buffer zone in an annular geometry.

This study describes the effects of wormlike micelles formed by the commercial surfactants tallowalkylamidopropyl dimethylamine oxide (Aromox APA‐TW) and oleyl methyl bis(2‐hydroxyethyl) ammonium chloride (Ethoquad O/12) as drag reducers. Ethoquad O/12 is immune to degradation by heat and microorganisms. Conversely, Aromox APA‐TW is biodegradable in the environment, and its susceptibility to heat‐induced degradation was previously assessed. This work considers the effects of temperature, salt, and time on the drag‐reduction capacity (in different Reynolds number) of wormlike micelles of these two surfactants. Wormlike micelles formed by Aromox APA‐TW are able to reduce drag at higher temperatures compared to wormlike micelles formed by Ethoquad O/12. However, Aromox APA‐TW can degrade after being heated to 80 °C and also after storage of the wormlike micelle solutions. Ethoquad O/12 does not undergo degradation after being heated or stored. These surfactants have the potential to be used as additives in industrial operations, as the wormlike micelles formed are able to reduce drag in systems with long pumping distances or recirculation, even in solutions with high salt concentrations (brine) and high temperatures.

The flow inside a horizontal annulus due to the inner cylinder rotation is studied. The bottom of the annular space is partially blocked by a plate parallel to the axis of rotation, thereby destroying the circumferential symmetry of the annular space geometry. This flow configuration is encountered in the drilling process of horizontal petroleum wells, where a bed of cuttings is deposited at the bottom part of the annulus. The velocity field for this flow was obtained both numerically and experimentally. In the numerical work, the equations which govern the three-dimensional, laminar flow of both Newtonian and power-law liquids were solved via a finite-volume technique. In the experimental research, the instantaneous and time-averaged flow fields over two-dimensional meridional sections of the annular space were measured employing the particle image velocimetry (PIV) technique, also both for Newtonian and power-law liquids. Attention was focused on the determination of the onset of secondary flow in the form of distorted Taylor vortices. The results showed that the critical rotational Reynolds number is directly influenced by the degree of obstruction of the flow. The influence of the obstruction is more perceptible for Newtonian than for non-Newtonian liquids. The more severe is the obstruction, the larger is the critical Taylor number. The height of the obstruction also controls the width of the vortices. The calculated steady-state axial velocity profiles agreed well with the corresponding measurements. Transition values of the rotational Reynolds number are also well predicted by the computations. However, the measured and predicted values for the vortex size do not agree as well. Transverse flow maps revealed a complex interaction between the Taylor vortices and the zones of recirculating flow, for moderate to high degrees of flow obstruction.

Dam break problems occur in a variety of applications. In the present paper we are especially concerned with the mining industry, where a dam break can be a catastrophic event with significant harm to the environment. In this case, the materials involved have a yield stress property, i.e., they flow only when a threshold is overcome by the stress that acts on the material. The plastic number, which measures the importance of the yield stress in the overall characteristic stress, is the main dimensionless number analyzed, and carbopol solutions are the kind of material employed. Since slip is common in motions of yield stress materials, the influence of this phenomenon is investigated by a comparison between the flow over a smooth and a rough surface. An image processing that captures the evolution of the shape of the interface as well as particle image velocimetry measurements were employed as tools to understand the role played by the plastic number in the problem. A number of cases presented a triangular depression that originated from a difference between the flow below the initial yield surface position and a rigid body motion above the initial surface position.