A novel alkali-surfactant for optimization of filtercake removal in oil–gas well

The main objective of this study is to improve the oil-based filtercake removal at the wellbore second interface through chemical method. The reductions in near-well permeability, bonding strength at wellbore second interface and acidizing treatment are the critical problems in oilfield upstream operations. One of the major causes has been identified as drilling fluid filtrate invasion during the drilling operations. This as result leads to near-well reduction in-flow capacity due to high drawdown pressure and wellbore instability. A number of chemical methods such as enzymes, acids, oxidizers, or their hybrids, have been used, however, due to the presence of a number of factors prior to its removal, there are still many challenges in cleaning oil-based filtercake from the wellbore surface. There is a need for development an effective method for improving oil-based filtercake removal. This study presents a novel Alkali-Surfactant (KV-MA) solution developed in the laboratory to optimize the filtercake removal of oil–gas wellbore. The Reynold number for KV-MA solution was found to be 9,068 indicating that turbulent flow regime will dominate in the annulus which enhances the cleaning efficiency. The wettability test established that, contact angle of 14° was a proper wetting agent. The calculated cleaning efficiency was 86.9%, indicating that it can effectively remove the oil-based filtercake. NaOH reacts with the polar components in the oil phase of the oil-based filtercake to produce ionized surface-active species; hence reducing the Interfacial Tension. Surfactant quickens the diffusion of ionized species from the interface to the bulk phase.

Flow Characteristic Research of Children Subjected to Obstructive Sleep Apnea-Hypopnea Syndrome

Revealing the structural morphology and inner flow field of the upper airway is important for understanding obstructive sleep apnea-hypopnea syndrome (OSAHS) incidence phenomena and pathological diagnosis in children. However, the present study is usually concentrated on adults, but achievement cannot be directly applied to children because of different inducing factors. Therefore, this paper employs flow characteristics and a simulation method for child OSAHS. It is found that the Reynold number changes highly throughout the whole upper airway, and the laminar assumption is no longer suitable for low Reynold number flow, which is much unlike classic fluid mechanics. Turbulent models of Standard k-ω and Spalart-Allmaras were developed prior to suggestion. The simulation is validated by experiments with an error of approximately 20%. Additionally, carried out in this analysis is the influence of adenoidal hypertrophy with different narrow levels. The cross-sectional area, flow velocity, pressure drop and volume rate will change greatly when the narrow level is above 64% of the upper airway, which can be a quantitative explanation for medical intervention if adenoid hypertrophy blocks 2/3 of the upper airway in the common clinical judgment of otorhinolaryngology. It is expected that this paper can be a meaningful instruction on OSAHS surgery plan making as well as recovery evaluation postoperatively.

Numerical Investigation Aerodynamic Characteristic Installation I-65° Cylinder Type Upstream Bluffbody as Airflow Passive Control

This report is the basic research that focuses on efforts to reduce the drag force of a cylindrical pipe by placing an interfering cylinder in the area of the incoming flow direction. The aerodynamic behavior of the central cylinder and its disturbances were modeled in 2D are discretized in laminar flow by Finite Volume Methode using Ansys Fluent®. Efforts to reduce the drag force are carried out with the main cylinder diameter D=60 mm and the interfering cylinder type I-65° with diameter d/D = 0.125. The distance between the center points of the two cylinders being s/D=1,4 and Reynold number Re = 5.3 x 10 4 at a speed of U∞=14 m/s. Numerical simulation using variations of turbulent models k-epsilon (2eq), k-omega (2eq), and transition k-kl-omega (3eq). The results of this research can show better aerodynamic performance. Placing the cylinder I-65° in tandem can reduce the average drag force coefficient by 68% at 700-800 timesteps. In contrast, the average lift coefficient decreased by 13% at the same timestep. The results were obtained with transition k-kl-omega (3eq) turbulence models that have been validated and able to approach the referenced experimental data.

Flow Past a Fixed and Freely Vibrating Drilling Riser System with Auxiliaries in Laminar Flow

Drilling risers used in oil and gas operations are subjected to external loads such as wave and current. One of the phenomena that arise from the external loads is the Vortex-Induced Vibration (VIV), which affects the performance of the riser due to excessive vibration from the vortex shedding. A significant factor influencing the VIV is the design of the drilling riser and its auxiliary lines. Until now, the optimum geometrical size and gap between the auxiliary and the main riser are still very scarcely studied. In this paper, the main objective is to study the effects of the gap ratio (G/D) on the vortex shedding phenomenon on a fixed and freely vibrating riser. The riser system was modelled with a main drilling riser and six auxiliary lines with a constant diameter ratio (d/D) of 0.45 and gap ratio (G/D) = 0 to 2.0 in the laminar flow regime with Reynold Number, Re = 200. The simulations were conducted for Single Degree of Freedom (SDOF) using Computational Fluid Dynamics (CFD) software, Altair AcuSolve. It was found that the freely vibrating riser experienced higher lift and drag forces as compared to the fixed riser due to the synchronization (lock-in) of the shedding vibration and the natural frequencies. The lock-in phenomenon is normally observed on the drilling riser at different current directions. The forces are reduced when G/D is higher. The vortex shedding was significantly reduced for auxiliaries between 0.3 to 1.4. It is confirmed that by modifying the interaction of the vortices in the wake region with auxiliary lines, the hydrodynamic forces will be decreased. Finally, this fundamental study could potentially be used in the designing stage of an optimum drilling riser system by considering significant governing factors.

Dufour and Soret Effect on Viscous Fluid Flow between Squeezing Plates under the Influence of Variable Magnetic Field

The aim of this article is to investigate the effect of mass and heat transfer on unsteady squeeze flow of viscous fluid under the influence of variable magnetic field. The flow is observed in a rotating channel. The unsteady equations of mass and momentum conservation are coupled with the variable magnetic field and energy equations. By using some appropriate similarity transformations, the partial differential equations obtained are then converted into a system of ordinary differential equations and are solved by Homotopy Analysis Method (HAM). The influence of the natural parameters are investigated for the velocity field components, magnetic field components, heat and mass transfer. A direct effect of the squeeze Reynold number is observed on both concentration and temperature. Moreover, increasing the magnetic Reynold number shows an increase in the fluid temperature, but in the case of concentration, an inverse relation is observed. Furthermore, a decreasing effect of the Dufour number is observed on both concentration and temperature distribution. Besides, in case of the Soret number, a direct effect is observed on concentration, but an inverse effect can be seen on temperature distribution. Different effects are shown through graphs in this study and an error analysis is also presented through tables and graphs.

Thermo-Fluidic Modelling of a Heat Exchanger Tube with Conical Shaped Insert having Protrusion and Dimple Roughness

In the present work, thermo-fluidic behavior of a heat exchanger tube with conical shaped insert has been investigated with the help of finite volume method. To enhance the heat transfer rate, two different types of roughness has been used in conical insert i.e. protrusion and dimple roughness. A three-dimensional computational model with RNG turbulence model is used for the simulation and it has been performed for three different diameters (3 mm, 6 mm and 9 mm) and two different pitch space (120 mm and 180 mm) for both protrusion and dimple roughness. The present model has been validated with Dittus-Boelter equation and with Blasius equation for Nusselt number and friction factor, respectively. For a constant heat flux of 1200 W/m2, effect of roughness, diameter and pitch on Nusselt number and friction factor has been predicted for Reynold number range of 5000 to 30000. From the result, it is found that, the protrusion shaped roughness has better thermal performance factor than dimple shape and diameter of 6 mm has performed better than 3 mm and 9 mm for both the cases of roughness due to favorable flow dynamics.

PERILAKU CHAOS ALIRAN FLUIDA BERDENYUT DALAM SALURAN BERPENAMPANG SEGIEMPAT

The pulsatile fluid flow in a transverse grooved channel would become chaotic flows in low Reynold numbers. The Reynold number where flows become chaos depends on grooves distances. The objective of this research is to analyze the effect of grooves distances on the behavior of chaos. This research was done by implementing a closed square cross-section channel, where the bottom surface of the channel was semicircle grooved. The frequency of flow oscillation measurement was done by setting up a resistance sensor that is Wheatstone bridge where the resistance sensor was located in a U manometer. Measurement was done at several Reynold number. From the research result, it is seen that the periodic fluid flows in the transverse grooved channel had become chaos at Reynold number Re 950 in the channel without grooved and at Reynold number Re 700 in the grooved channel. Chaos took placed since a vortex appeared at every treatment.

An Investigation of the Effects of Volume Fraction on Drag Coefficient of Non-Spherical Particles Using PR-DNS

Prediction of the drag coefficient is required in gas-particle multiphase flow modeling and simulation. Experimental data and correlations on the fixed-bed system of spherical particles with high volume fractions for various possible arrangements are available in the literature. However, the effect of volume fraction on the drag coefficient of non-spherical particles is not well studied. In solving the momentum equation, the volume fraction plays a vital role in determining the flow resistances. In this paper, we study the impact of volume fraction in the range of 0.069 to 0.65 on the drag coefficient using the computational fluid dynamics (CFD) simulation of air for Reynold number in the range of 10 to 10000 using particle resolved direct numerical solution (PR-DNS). Regular non-spherical particles such as a cube, tetrahedron, and spheroids are used in this study since their single particle’s drag coefficient data are available in the literature for comparison. For this work, the simulations are carried out in the Ansys Fluent using polyhedral mesh, which consumes significantly less computational time and power. The study showed the sphericity and volume fraction have significant impact on the bed pressure drop and average drag coefficient of the particles in the bed especially in high Reynolds number regime. The bed of the spheroid experiences the lowest drag being the most streamlined particle, and the particles with the edges result in a large drag coefficient due to flow separation at the discontinuity. The vector plots verify this behavior where large wake regions are observed behind the tetrahedron particle.

Aerodynamic Differences between New and Used Soccer Balls

The surface structure of soccer balls, such as the number and shapes of the ball panels, has recently changed, and research on the aerodynamics and flight trajectories of new soccer balls is actively proceeding. However, these studies are focused on new soccer balls, whereas the used soccer balls were never studied. In this study, the aerodynamic characteristics of soccer balls kicked 1000 times by a robot were investigated through wind tunnel tests. The results were compared with those obtained using new soccer balls. Regarding the aerodynamic characteristics of the soccer balls, it was found that the critical Reynold number, Recrit, changes with usage. This is related to the transition from laminar to turbulent flow of airflow around the ball. The comparison of the drag coefficients of the balls at Recrit showed that the drag coefficients of the new and used Telstar18 balls were 0.15 (Re = 2.5 × 105) and 0.14 (Re = 2.2 × 105), respectively; those of the new and used Merlin were 0.13 (Re = 2.8 × 105) and 0.13 (Re = 2.2 × 105), respectively; and finally, those of the new and used Derbystar were 0.14 (Re = 2.1×105) and 0.14 (Re = 2.1×105), respectively. The surface conditions of a soccer ball, such as the surface roughness and surface damages, are essential factors to determine the aerodynamics of the soccer balls.

PENGARUH JARAK ALUR TERHADAP KESTABILAN ALIRAN FLUIDA BERDENYUT DALAM SALURAN BERPENAMPANG SEGIEMPAT

The pulsatile fluid flow in a transverse grooved channel would become self-sustained oscillatory flow at a certain critical Reynold number. The critical Reynold number where laminar unsteady flow changed to unsteady transitional one depends on grooves distances. The objective of this research is to analyze the effect of grooves distances toward the vortex strength and the stability of the fluid flow. This research was done by implementing a closed square cross-section channel, where the bottom surface of the channel was semicircle grooved. The frequency of flow oscillation measurement was done by setting up a resistance manometer and measurement was done at several Reynold numbers. From the research result, it is seen that the largest vortex strength occurs at the smallest groove distance. The flows become instability in all of the grooves distances by seen Phase Plane.