Majid Bizhani

Experimental Investigation of Drag Reducing Fluid Flow in Annular Geometry Using Particle Image Velocimetry Technique

Fully developed turbulent flow of drag reducing fluids through a horizontal flow loop with concentric annular geometry was investigated using the particle image velocimetry (PIV) technique. Experiments were conducted at solvent Reynolds numbers ranged from 38,700 to 56,400. Axial mean velocity profile was found to be following the universal wall law close to the wall (i.e., y+ 30). The study was also focused on turbulence statistics such as near wall Reynolds stress distribution, axial and radial velocity fluctuations, vorticity and turbulent kinetic energy budget.

A Comparative Study of Hole Cleaning Performance — Water Versus Drag Reducing Fluid

Effective hole cleaning in horizontal and extended reach wells (ERD) often requires use of high circulation rates, which may not be always achievable due to the risk of circulating bottom hole pressure reaching the fracture limit of the rock. Achieving good hole cleaning while keeping the circulating bottom hole pressure within the safe operational window is very often the major engineering challenge. A drag reducing fluid with good hole cleaning ability could be a potential solution in this case.In order to see if it is possible to use a drag reducing fluid and still achieve a good hole cleaning, an experimental program was designed and conducted. The main objective of this experimental study was to compare the hole cleaning performances of water and a drag reducing fluid.The hole cleaning experiments were conducted using a 9m long horizontal flow loop with concentric annular geometry (Outer Pipe ID = 95 mm, Inner Pipe OD = 38 mm, ID/OD ratio = 0.4). The drag reducing additive was a commercially available partially hydrolyzed polyacrylamide (PHPA). Water and two drag reducing fluids with 0.07% V/V and 0.1% V/V PHPA concentrations were used. Critical velocities for the initiation of cuttings movement with rolling, saltation/dunes, and suspension modes were determined and compared when using water and drag reducing fluids as a carrier fluid. Critical velocities for the initiation of cuttings movement were found to be lower with water than that of drag reducing fluid in all transport modes.Copyright

Turbulent structure at the midsection of an annular flow

The turbulent flow in the midsection of an annular gap between two concentric tubes at Reynolds number of 59 200–90 800 based on hydraulic diameter (dh = 57 mm) and average velocity is experimentally investigated. Measurements are carried out using particle tracking velocimetry (PTV) and planar particle image velocimetry (PIV) with spatial resolution of 0.0068dh (size of the binning window) and 0.0129dh (size of the interrogation window), respectively. Both PTV and PIV results show that the location of maximum mean streamwise velocity (yU) does not coincide with the locations of zero shear stress (yuv), minimum streamwise velocity fluctuation (yu2), and minimum radial velocity fluctuation (yv2). The separation between yU and yuv is 0.013dh based on PTV while PIV underestimates the separation distance as 0.0063dh. Conditional averages of turbulent fluctuations based on the four quadrants across the annulus demonstrate that the inner and outer wall flows overlap in the midsection. In the midsection, the flo...

Turbulent Structure of a Concentric Annular Flow

Turbulent flow in the annular gap between two concentric tubes of 38 and 95 mm diameter at Reynolds number of 79’000 is experimentally investigated. Measurements are conducted using planar particle image velocimetry (PIV) with spatial resolution of 23 \(\upmu \)m/pix and interrogation windows of 0.74 \(\times \) 0.74 mm\(^{2}\). The experiments are aimed at scrutinizing the location of the extremums of the asymmetric profiles of velocity and turbulent statistics along with the relevant turbulent structures. The location of maximum average streamwise velocity \( _\mathrm{max}\) and zero Reynolds shear stress \( \) are observed to be apart. Local minimum of \( \) and \( \) is also observed to coincide with \( \, = 0\) and different from \( _\mathrm{max}\). The experiments also demonstrate that the ejection events originating from the inner and outer walls play a dominant role in transport of turbulence toward the midsection of the annulus.

Modeling Turbulent Flow of Non-Newtonian Fluids Using Generalized Newtonian Models

Computational Fluid Dynamic (CFD) is used to model turbulent flow of non-Newtonian polymeric fluids in concentric annulus. The so called Generalized Newtonian Fluid (GNF) approach is used. Four turbulence models are tested. Applicability of each model in predicting turbulent flow of non-Newtonian fluids in annulus is assessed by comparing results of pressure loss and or velocity profiles with experimental data.The first tested model is a modified version of Lam-Bremhorst k–e turbulence model. The modification was originally developed to model flow of power law fluids in smooth circular pipes. Results of simulation study showed that this model significantly overestimates the pressure losses.Two k–e closure type turbulence models, one developed to model turbulent flow of Herschel-Buckley and the other for power law fluids, are shown to fail in predicting turbulent flow of polymer solutions. One of the models contains a damping function which is analyzed to show its inadequacy in damping the eddy viscosity.The last tested model is a one layer turbulence model developed for predicting turbulent flow in annular passages. The model has an adjustable parameter, which is shown to control the slope of velocity profiles in the logarithmic region. It is demonstrated that if the model constant is selected carefully, the model accurately predicts pressure loss and velocity profiles.Copyright

An Experimental Study of Turbulent Non-Newtonian Fluid Flow in Concentric Annuli Using Particle Image Velocimetry Technique

Turbulent flow of a Non-Newtonian polymeric fluid through concentric annuli is studied using a 9 m long horizontal flow loop (radius ratio = 0.4). The measurement technique used is Particle Image Velocimetry (PIV). The solvent Reynolds number is found to vary from 47000 to 66400. Pressure drops are measured and used to detect the onset of transition to turbulence. Measured velocity profiles are found to agree with the universal law of the wall for y + < 11. In the logarithmic region, however, velocity profiles deviate from log law, in a manner consistent with the flow of Newtonian fluids. Reynolds stress is found to be reduced significantly compared to water. The polymer is found to contribute significantly to the total stress close to the solid walls. The radii of maximum velocity are found to be biased toward the inner wall. Results of the turbulence intensity analysis show a slight increase of axial intensities in the buffer layer and especially around the outer wall of the annuli for polymer solutions. Radial velocity fluctuations are suppressed by means of polymer solution. The Root Mean Square (RMS) of vorticity fluctuation in the axial direction is also analyzed revealing a significant reduction of vortical activities as polymer is added to the flow.

An Experimental Study of the Effect of Drag Reducing Additive on the Structure of Turbulence in Concentric Annular Pipe Flow Using Particle Image Velocimetry Technique

The effect of drag reducing additive on the structure of turbulence in concentric annular pipe flow was investigated using Particle Image Velocimetry (PIV) technique. Experiments were conducted using a 9m long horizontal flow loop with concentric annular geometry (inner to outer pipe radius ratio = 0.4). The drag reducing additive was a commercially available partially hydrolyzed polyacrylamide (PHPA). The experiments were conducted using 0.1% V/V polymer concentration, giving a drag reduction of 26% at a solvent Reynolds number equal to 56400.Near wall local fluctuating velocity values were determined by analysing the PIV data. The root mean square (RMS) values of radial velocity fluctuations showed a significant decrease with the use of drag reducing additive. The RMS values of axial velocity fluctuations near the wall (Y+<10) were similar for both water and polymer fluid flow; though, higher peaks were obtained during the polymer fluid flow.As compared to water flow, a strong reduction in vorticity was observed during polymer fluid flow. The degree of vorticity reduction on the inner wall was higher than that of the outer wall.Results of the viscous dissipation and the shear production terms in the kinetic energy budget showed that less energy was produced and dissipated by the route of turbulence when using polymer fluid.Copyright

Near Wall Turbulence Characteristics of a Drag Reducing Polymer Fluid Flow in Concentric Annulus Using CFD

A CFD simulation was conducted to analyze the near wall turbulence characteristics of a drag reducing (DR) polymer fluid (0.12% V/V) flow through concentric annulus. The continuity and momentum equations were solved by using a commercial CFD package (CFX 14) with the Shear-Stress-Transport (SST) model option. The simulation results were compared to the experimental data obtained by using high resolution Particle Image Velocimetry (PIV) analyses of drag reducing polymer fluid flow in a horizontal concentric annulus. A fully developed turbulent flow of water through a horizontal flow loop (ID = 9.5 cm) with concentric annular geometry (inner to outer pipe radius ratio = 0.4) was used for comparison purpose. The flow rates ranged from 3.92 to 5.95 kg/s. Drag reducing PHPA solutions behaved as a power law fluid with the rheological model (μ = Kγn−1) for the shear rate of 1/s to 600/s.Bulk and near wall velocity profile obtained from simulation showed good agreements with the experimental data. Drag reducing polymer reduce the Reynolds stresses level due to weaker and fewer turbulent eddies formation near the wall. Results of the simulation study also showed that if the flow rates of power law fluid increased from 3.92 to 5.95 kg/s, the drag reduction in the annuli is increased from 10% to 20% compared to water case indicating the strong damping to turbulent kinetic energy in the flow. The CFD analyses using SST model is computationally inexpensive and, therefore, can be conveniently used for investigating the flow characteristics of drag reducing polymer fluids in concentric annulus.Copyright

An Experimental Investigation of Turbulent Drag Reduction in Concentric Annulus Using Particle Image Velocimetry Technique

Polymer drag reduction is investigated using the Particle Image Velocimetry (PIV) technique in fully developed turbulent flow through a horizontal flow loop with concentric annular geometry (inner to outer pipe radius ratio = 0.4). The polymer used was a commercially available partially hydrolyzed polyacrylamide (PHPA). The polymer concentration was varied from 0.07 to 0.12% V/V. The drag reduction is enhanced by increasing polymer concentration until the concentration reaches an optimum value. After that, the drag reduction is decreased with the increasing polymer concentration. Optimum concentration value of PHPA was found to be around 0.1% V/V. Experiments were conducted at solvent Reynolds numbers of 38700, 46700 and 56400. The percent drag reduction was found to be increasing with the increasing Reynolds number.The study was also focused on analyzing the mean flow and turbulence statistics for fully-turbulent flow using the velocity measurements acquired by PIV. Axial mean velocity profile was found to be following the universal wall law close to the wall (i.e., y+ 30). In all cases of polymer application, the viscous sublayer (i.e., y+ <10) thickness was found to be higher than that of the water flow. Reynolds shear stress in the core flow region was found to be decreasing with the increase in polymer concentration.Copyright

A CFD Simulation of Near Wall Turbulent Flow in Concentric Annulus

A CFD simulation study was conducted to analyse the near wall turbulence characteristics of water flow through concentric annulus. The continuity and momentum equations were solved by using a commercial CFD package (CFX 14) with the Shear-Stress-Transport (SST) model option. The simulation results were compared to the experimental data obtained by using high resolution Particle Image Velocimetry (PIV) analyses of water flow in a horizontal concentric annulus. A fully developed turbulent flow of water through a horizontal flow loop (ID = 9.5 cm) with concentric annular geometry (inner to outer pipe radius ratio = 0.4) was used for comparison purpose. Reynolds number ranged from 17,500 to 68,500.Annular velocity profile obtained from simulation study showed good agreement with the experimental data. Near wall velocity profile obtained from CFD simulation followed the universal wall law (u+ = y+) up to y+ = 11. CFD analyses using the SST model resulted a good number of velocity data up to y+ = 11, which is normally a very difficult task to achieve experimentally.The CFD analyses using SST model is computationally inexpensive and therefore, can be conveniently used for investigating the near wall turbulent characteristics of flow in concentric annulus.Copyright