Flow In Concentric Annuli Research Articles

Experimental investigation of the effect of drill pipe rotation on improving hole cleaning using water-based mud enriched with polypropylene beads in vertical and horizontal wellbores

Field experience has shown that the inefficient transport of small cuttings is a main factor contributing to excessive drag and torque during the drilling of a deviated hole; however, very little is known about the transport behavior of small cuttings. This experimental study investigates the effect of different polypropylene bead concentrations in water-based mud (WBM) on hole cleaning, along with the effects of cutting size, drill pipe rotation, and hole inclination angle. A total of 160 runs were performed using an experimental rig consisting of a 13 ft (3.96 m) long casing with a 2 in (50.8 mm) Inner Diameter (ID) and a rotary inner pipe with a 0.8 in (20 mm) Outer Diameter (OD). Four cutting size ranges, namely, 0.5–1.0 mm, 1.0–1.4 mm, 1.4–1.7 mm, and 1.7–2.0 mm, with a density of 2400 kg/m3 were tested in WBM with varying polypropylene bead concentrations ranging from 0 to 8 ppb. The concentric annulus flow test section was changed to vertical and horizontal angles with pipe rotation from 0 to 150 rpm. The mud density and viscosity were maintained at 10 ppg and 16 cp, respectively, under a flow velocity of 3.48 m/s (Reynolds number of 6620). The results indicate that smaller cuttings are easier to transport at all pipe rotations and polypropylene bead concentrations in both vertical and horizontal holes. The optimal pipe rotational speed was found to be 60 rpm. In this study, polypropylene beads undeniably enhanced the mud carrying capacity by significantly increasing the cutting transport ratio (CTR) by up to 16.57% in vertical holes and 15.73% in horizontal holes.

A Liquid-Solid Two-phase Flow Computational Fluid Dynamic Modelling of the Operational Characteristics Effects on the Cleaning Time of a Circulating Flow Loop

Flow loops and computational fluid dynamics are the main research approaches for resolving the hole-cleaning problems. Cutting transport phenomena can be considered as a Computational Fluid Dynamic (CFD) model by using Eulerian assumptions for the turbulent liquid-solid flow in concentric annuli. The effect of time along with the main operational characteristics on the hole-cleaning phenomena is not negligible but recent studies have had paid little attention to it. Poor near bit cleaning causes many problems such as bit balling, decline in the rate of penetration, pipe sticking, etc. In addition to the effect of inclination, drill pipe rotary speed, cutting size, nozzle velocity and fluid viscosity as well as the effect of the bit nozzle arrangement on the cutting transport process were discussed. The results demonstrate that at a critical inclination angle of 30 degrees the cutting transport is inefficient. For all sections, the effect of drill pipe rotary speed was negligible at high velocities. In the horizontal section, at low flow rates and high drill pipe rotation speeds, Newtonian viscous fluids or water has no effect on the time needed for initial hole-cleaning butby removing the drill pipe rotation speed in similar conditions, a dramatic influence on time is observed. In inclined annuli, increasing the cuttings size and decreasing the nozzle velocity result in having no cutting in the output. Under critical inclination (30 degrees) the effect of the nozzle angle pattern on the hole-cleaning time is negligible. However, for a vertical annulus, the nozzle angle significantly influences the cutting transport. The best performance is obtained when the nozzle angle was perpendicular to the drill pipe axes. Keywords: Two-phase flow, flow characteristics, CFD, jetting flow.

擬塑性流体同心二重円管内層流における流動特性値決定法および圧力損失

The flow through annuli is encountered in drilling operation, in which drilling mud flows between the borehole wall and the drilling pipe. Some drilling muds, depending on their prepared materials, exhibit nonNewtonian characteristics and in many cases may be regarded as pseudoplastic fluids. This study examines the dimensionless flow rate defined by Fredrickson and Bird (Fredrickson and Bird, 1958) on pseudoplastic fluid laminar flow in concentric annuli. A new approximation function is derived to evaluate the viscosity factor, also easy to use without numerical procedures. The function is more precise than the one, which was previously shown by the authors (Masuyama and Hatakeyama, 2003). Further, a new scheme is proposed to evaluate the characterizing coefficients, such as the pseudoplastic viscosity and the rheology constant using flow data. Furthermore, generalized formulas of the Reynolds number and the pipe friction coefficient for pseudoplastic fluid are shown for concentric annuli in order to calculate the pressure drop. They are extendable in the case of circular pipes, also parallel plates.

RANS Based Computational Fluid Dynamics Simulation of Fully Developed Turbulent Newtonian Flow in Concentric Annuli

A computational fluid dynamics (CFD) simulation is performed via ansys–CFX for a fully developed turbulent flow in concentric annuli with two radius ratios (R1/R2 = 0.4 and 0.5) at three Reynolds numbers (Re = 8900, 26,600, and 38,700) in terms of the hydraulic diameter D and the bulk velocity Ub. Near-wall turbulence structures close to the inner and outer walls are characterized by analyzing the first-order and second-order statistics. Effects of transverse curvature and the Reynolds number on development of the turbulence structures are emphasized. This study demonstrates the ability to predict the asymmetric features of turbulent flows in annular pipes by using the Reynolds-Averaged Navier–Stokes (RANS) model. Estimation of viscous dissipation in the flow using a RANS model is compared with direct numerical simulation (DNS) results for the first time.

Electromechanical Conversion of Low-Temperature Waste Heat Via Helical Shape Memory Alloy Actuators

An energy harvesting prototype (EHP) was designed to convert low-temperature heat loss from fluid into electricity. The method for energy conversion uses two antagonistically connected shape memory alloy (SMA) actuators to rotate a shaft that is connected to a generator. Heat transfer equations for concentric annular flow are modeled. The relationship between SMA temperature and shaft angular rotation is derived from a semiempirical SMA stress–temperature model and Ozdemir's SMA stress–strain equations. The simulated generator shaft rotation and generator voltage are in close agreement with the corresponding experimental results. Additional experiments were conducted to compare the ability of spring and linear SMA wires to convert low-temperature heat lost from water into electricity. The linear SMA generated a peak 0.3 V, whereas the spring-shaped SMA generated a peak of nearly 5 V. On average, 7.4 mJ of energy per 2.5 s cycle was stored in a 6-F capacitor attached to the generator output. It is concluded that the EHP has a strong potential to recuperate low-temperature wasted heat.

Entrance region flow in concentric annuli with rotating inner wall for Bingham fluid

Entrance region flow in concentric annuli with rotating inner wall for Bingham fluid

Numerical investigation of the concentric annulus flow around a cylindrical body with contrasted effecting factors

This paper studies the wall-bounded flow around a cylindrical at a high Reynolds numbers body in a determined computational domain, with simulations of the 3-D, turbulent concentric annulus flow in a straight pipe. Numerical results show that a reversing zone, appearing as a tongue zone with nested velocities higher than the surrounding area, exists behind the cylindrical body. The annulus space is a region of high velocity and low pressure. The zero velocity, of combined the velocity and the velocity, exists in the cross sections and no vortex shedding is formed behind the attaching cylinders. Among all investigated effecting factors, the diameters of the attaching and the main cylinders affect the wake feature behind the cylindrical body while the main cylinder length does not affect the distribution tendency of the flow field. The diameters of the main cylinder and the pipe affect the pressure values and the distribution tendencies on the main cylinder surface. Obviously, the increase of the pipe diameter reduces the drag coefficient of the cylindrical body and the increase of the diameter of the main cylinder increases the drag coefficient greatly. The numerical investigation of the concentric annulus flow provides foundations for further improvements of the intricate flow studies.

English

This research work presents the experimental results of the effect of polypropylene beads' concentrations in waterbased mud on wellbore cleaning. A comparative study of cuttings transport performance (CTP) of water-based mud and water-based mud with polypropylene beads were carried out at different hole angles of 0°, 30°, 60°. 75° and 90° in a 13 ft (3.96 m) acrylic concentric annulus flow test section, having a 2 in (50.8 mm) casing ID and a fixed 0.79 in (20 mm) inner pipe OD. A total of 100 runs had been accomplished using fine sands (from Tanjung Balau, Johor Bahru, Malaysia), of size ranging from 5/127-6/127 (1.0-1.2 mm) and density 2.4 g/cc (2400 kg/m3), with the mud density and viscosity maintained at 9 ppg (1078 kg/m3) and 5 cp (0.005 Pa.s), respectively, in a flow velocity of 2.1 ft/s (0.64 m/s). Polypropylene beads used in this study have the following properties: 290 kg/cm2 of tensile strength at yield, 0.86 g/cc (860 kg/m3) density, 4 mm (20/127) size, 82 R scale Rockwell hardness, 13,500 kg/cm2 flexural modulus, 85°C heat deflection temperature at 4.6 kg/cm2, 4 g/10 min melt flow rate at 230°C and spherical in shape. The experimental findings showed that commingling the basic mud with polypropylene beads has successfully introduced a buoyant force which was found to have improved the cuttings transport performance by more than 10% when weight concentration of the polypropylene beads was increased to 1.5% as compared with the performance obtained from the basic water-based mud. The improvement of cuttings transport performance was found to be more significant in a vertical hole.

3-D numerical investigation of the wall-bounded concentric annulus flow around a cylindrical body with a special array of cylinders

Concentric annulus flow around a combinational cylindrical body with a special array of cylinders at five high Reynolds numbers is investigated numerically using Fluent 6.3.26 in this paper. The numerical results show a good agreement with the experimental data in regard to the axial velocity of the flow. This study focuses on the flow structure and the hydrodynamic characteristics based on the velocity distribution, the pressure distribution, streamlines and vectors under 1-D, 2-D and 3-D conditions. Meanwhile, some global parameters including the pressure coefficient, the drag coefficient and the lift coefficient are analyzed. Numerical results show that the high velocity region and the reverse wake zone with low velocity exist in some spaces due to the disturbance of the cylindrical body. Negative pressures appear in some regions. Neither a wide area vortex nor the vortex shedding appears in the wall-bounded domain. The drag along the axial direction is the main force acting on the cylindrical body in the pipe domain. The annulus flow around the cylindrical body is analyzed to reveal the hydrodynamic characteristics of the complex turbule- nt concentric annulus flow field due to the multi-effects in the pipeline.

Entrance Region Flow in Concentric Annuli with Rotating Inner Wall for Herschel–Bulkley Fluids

A finite difference analysis of the entrance region flow of Herschel–Bulkley fluids in concentric annuli with rotating inner wall has been carried out. The analysis is made for simultaneously developing hydrodynamic boundary layer in concentric annuli with the inner cylinder assumed to be rotating with a constant angular velocity and the outer cylinder being stationary. A finite difference analysis is used to obtain the velocity distributions and pressure variations along the radial direction. With the Prandtl boundary layer assumptions, the continuity and momentum equations are solved iteratively using a finite difference method. Computational results are obtained for various non-Newtonian flow parameters and geometrical considerations. A significant asymmetry is found in the entrance region which is gradually reduced as the flow develops. For smaller values of aspect ratio and higher values of Herschel–Bulkley number the flow is found to stabilize more gradually. Comparison of the present results with the results available in literature for various particular cases has been done and found to be in agreement.

Numerical simulation of velocity profile in eccentric annulus

Annulus flow is a phenomenon which is frequently encountered in many industrial processes and has been under investigation for many decades. It is relatively simple to study concentric annulus flow. However, if the annulus is eccentric, calculations become complex due to the asymmetry of the eccentric annulus flow. During drilling operation, the space between the drill stem and the well wall is generally an eccentric annulus. Especially in highly deviated wells and horizontal wells, the drill stem will be located at the low side of the wellbore because of gravitational effects, thus, a fully eccentric annulus is formed. The velocity profile in the eccentric annulus will exert a great impact on the transportation and distribution of the cuttings, which is very important to prevent the drill string from being buried and avert sticking incidents. Based on a single-phase flow model and a solidliquid two phase mixture drift model, (using the computational fluid dynamics (CFD) software) we analyze the influence of six factors in this paper. These factors are the • flow rate, • fluid viscosity, • the type of fluid, • eccentricity, • annulus geometry size and • cuttings concentration. According to the results of numerical simulation, we can see that the velocity profile in the eccentric annulus is asymmetrical. There will be a high-speed basin in the wide gap of the annulus while the low-speed basin will lie in the narrow gap. With increasing flow rate, annulus geometry size and a decrease of the eccentricity, the area of the high-speed basin in the annulus will be increased and that of the low-speed basin will be decreased. This will improve the uniformity of the annulus flow. With increasing fluid viscosity and cuttings concentration, the velocity in high-speed basin of the annulus will be increased, at the same time, the velocity in low-speed basin will be decreased and the change of the velocity is not evident. However, the pressure loss in annulus will increase rapidly. Therefore, we have to ensure that the velocity at the low-speed basin is large enough to transport the cuttings and to avoid the debris deposition in the drilling operation. At the same time, the borehole pressure should be taken into consideration when we select the reasonable drilling fluid viscosity.

Friction Pressure Prediction for Annular Flow of Power Law Fluids

This article examines the concentric and eccentric annular flow of non-Newtonian fluids. A new effective diameter definition that accounts for flow geometry and fluid rheology is presented for pressure loss prediction. Satisfactory agreements were obtained between this new effective diameter definition in combination with laminar Fanning friction factor correlations and extensive flow data in the literature. In addition, an explicit friction factor correlation as a function of the generalized Reynolds number, diameter ratio, and relative roughness is presented for a fully eccentric annular drag-reducing turbulent flow. A good agreement was obtained between this correlation and the gathered flow data. The correlations reported provide an effective means of determining friction pressures of non-Newtonian fluids in eccentric annuli.

A new utility calculation model for axial flow of non‐Newtonian fluid in concentric annuli

A new utility approach that is independent of the rheological model is presented for the flow of non‐Newtonian fluids in concentric annulus. The novel model was developed without assuming that the generalised flow index remains constant over all shear rate ranges. Based on the slot model, the flow rate expressions for all common rheological models flowing in annuli were obtained, such as the Herschel–Bulkley model, the Robertson–Stiff model, and the Four‐parameter model, and they all can be solved numerically to obtain accurate wall shear rate and shear stress. Following Metzner and Reed's study, we defined a generalised flow index for non‐Newtonian fluid flow in annuli. Through a theoretical analysis, we also defined a new effective diameter for non‐Newtonian fluid flow in annuli, which accounts for the effects both of annulus geometry and fluid rheology but which is different from that was proposed by Reed and Pilehvari. Through the generalised effective diameter we linked non‐Newtonian annular flow with Newtonian pipe flow. A general annular Reynolds number expression was derived from this method for conditions under which the generalised flow index is variable. A theoretical calculation method for the generalised flow index and a uniform pressure loss calculation model for non‐Newtonian flow in concentric annuli were developed, which are applicable to all time‐independent non‐Newtonian fluid. The predictions of this model have been compared with an extensive set of data from the literature. The comparisons of different fluids in different size annuli show very good agreement over the entire range of flow types.

Study of a magnetorheological fluid damper with multiple annular flow gaps

One of the challenges when engineering Magnetorheological (MR) fluid based devices is the development of a model that is capable of fairly accurate predictions of the device performance characteristics. In the case of MR dampers engineering and modeling studies are complicated due to a large number of multidisciplinary variables and mutual interactions between them. Therefore, it is the intent of the author to propose a math-based model of a monotube MR damper capable of simulating a wide range of piston configurations. The model utilizes a dimensionless representation of the Bingham model for simulating the fluid flow through the piston and data reduction. The study is complemented by extensive simulations of the magnetic circuit as well as the damper hydraulics. The model can be extended for the cases involving any number of parallel concentric annular flow paths in the piston. The obtained results are presented in the form of averaged flux density vs. coil ampere turns graphs, steady-state force-velocity maps and force-velocity as well as force-displacement phase planes, respectively.

A novel analytical method predicts plug boundaries of bingham plastic fluids for laminar flow through annulus

AbstractIn Bingham plastic fluids, a central pre‐yield or plug region exists in the middle of the concentric annular flow. In this region, the local shear stress is less than the dynamic yield stress, so the plug behaves like a rigid solid. This is the main feature that distinguishes the flow of a Bingham plastic fluid from that of a power law fluid. In this work, a simple‐to‐use correlation is developed to predict the boundaries of the plug of Bingham plastic fluids for laminar flow through annulus as a function of dimensionless yield stress and aspect ratio parameters for given values of the rheological constants, pressure gradient and the dimensions of the annulus. The results are found to be in excellent agreement with reported data in the literature with an average absolute deviation of less than 1.7%.The predictive tool is simple and straightforward and can be readily implemented in a standard spreadsheet program. The prime application of the method is as a quick‐and‐easy evaluation tool in engineering studies where plug boundaries of Bingham plastic fluids for laminar flow through annulus are being considered. The method may also serve as a benchmark in numerical and rigorous simulation studies.

Simulation of laminar and turbulent concentric pipe flows with the isogeometric variational multiscale method

We present an application of the residual-based variational multiscale modeling methodology to the computation of laminar and turbulent concentric annular pipe flows. Isogeometric analysis is utilized for higher-order approximation of the solution using Non-Uniform Rational B-Splines (NURBS). The ability of NURBS to exactly represent curved geometries makes NURBS-based isogeometric analysis attractive for the application to the flow through annular channels. We demonstrate the applicability of the methodology to both laminar and turbulent flow regimes.

Analytical solution for a vibrating simply-supported cylinder subjected to 2-D concentric annular flow, considering friction

An analytical model of annular-flow-induced vibration of a pinned–pinned cylinder is proposed. The model is based on three main assumptions: (i) small perturbations in flow components, (ii) negligible radial flow to reduce the annular flow to two-dimensional flow, and axial flow only for reduction to a one-dimensional flow, and (iii) perturbation frictional loss depending on the variation of axial perturbation velocity in terms of space and time. In this study, it is concluded that (a) the difference in fluidelastic forces between two- and one-dimensional flow models mostly depends on cylinder radius, and on whether perturbation flow is mainly allowed in the axial or circumferential direction, (b) the one-dimensional flow model should be limited to 1-d.o.f. vibration analysis or the case of a cylinder having a large radius-to-length ratio, and (c) the perturbation assumption has little effect on the dynamics of annular-flow-induced vibrations; however, the critical flow velocity is diminished considerably. Finally, preliminary results suggest that fluid friction may significantly modify the predicted model dynamics.

THE ISOGEOMETRIC VARIATIONAL MULTISCALE METHOD FOR LAMINAR INCOMPRESSIBLE FLOW

We present an application of the variational multiscale methodology to the com- putation of concentric annular pipe flow. Isogeometric analysis is utilized for higher order ap- proximation of the solution using Non-Uniform Rational B-Splines (NURBS) functions. The ability of NURBS to exactly represent curved geometries makes NURBS- based isogeometric analysis attractive for the application to the flow through the curved channel.

ESTIMATION OF LOCAL LIQUID FILM THICKNESS IN TWO-PHASE ANNULAR FLOW

In many semi-empirical analyses of flow boiling heat transfer, an annular flow is often assumed as a model flow and the local liquid film thickness is a key parameter in the analysis. This work considers a simple electrical conductance technique to estimate the local liquid film thickness in two-phase annular flows. In this approach, many electrodes are mounted flush with the inner wall of the pipe. Voltage differences between two neighboring electrodes for concentric annular flows with various liquid film thicknesses are obtained before the main experiments and logged in a look-up table. For an actual application in the annual flow, voltage differences of neighboring electrodes are measured and then corresponding local film thicknesses are determined by the interpolation of the look-up table. Even though the proposed technique is quite simple and straightforward, the numerical and static phantom experiments support its usefulness.

0316 粘性子午面解析による軸流タービン内部流れの評価(OS3 流体機械の研究開発とそれに関連した複雑流動現象,オーガナイズドセッション)

In the blade design process, flow pattern prediction tools have an essential role to create a highly efficient blade shape. A viscous throughflow code, which can take into account the effects of boundary layer and blade thickness, was developed to evaluate axial turbine flows. In the present paper, the throughflow code is validated by applying it to a concentric annular tube flow. In addition* axial turbine internal flows were evaluated by the throughflow code. The simulation results showed that the throughflow code can predict the flow patterns very well if the effects of secondary flow are marginal.