Annular Space Research Articles

Flow Of Visco Elastic {Oldroyd(1958)Model}Liquid Throughporous Medium And Theannular Space Between Tworightcircular Cylinders

Present paper is concerned with the oscillatory motion of visco-elastic [Oldroyd (1958) model] liquid through porous medium and the annular space between two right circular cylinders perpendicular to the flow of liquid when both the cylinders execute simple harmonic motion along the central axis of the cylinders. The amplitudes and frequencies have been taken different for both cylinders. The particular cases have also been discussed in detail. Thevelocity of visco-elastic liquid is effected by porous medium.

Numerical investigation of natural convection in concentric cylinder partially heated based on MRT-lattice Boltzmann method

In the present paper, a numerical simulation of natural convection flow in annulus space with a partially heated inner cylinder is proposed. The numerical investigation is based on lattice Boltzmann method (LBM) with multiple relaxation time approximation. Each heating partial side length's is about 25% of the inner perimeter and is maintained at hot temperature. The heated regions are placed on the inner wall in four different configurations while the outer cylinder is maintained at cold temperature. A study of effect of Rayleigh number varying over the range of 104 - 5 × 105 and various cylinder ratio on Nusselt number and both velocity and thermal fields is carried out. It is found that the Nusselt number increases with the increase of Rayleigh number and the radius ratio. Otherwise, the fourth configuration where the heated zones are placed on the left and right sides of the inner cylinder, offers the better rate heat exchange for a fixed value of Rayleigh number and radius ratio.

Enhancement of Double-Pipe Heat Exchanger Effectiveness by Using Water- CuO

This study utilized Nanofluid as a cold fluid in evaluating the counter flow double tube heat exchanger, which was one meter long, had an outer diameter of 19 mm, and an inner diameter of 9.5 mm made from copper. Water was the basic fluid, with the size of 40 nm and a volume concentration of (0.5%) and (1%), respectively, of CuO nanoparticles being added. At 2 L/min and 4 L/min and 6 L/min, the Nanofluid flows inside the inner tube. At 20°C, the Nanofluid enters the heat exchanger. The flow of hot water into the heat exchanger is 4 L/min through an annular space with an entry temperature of 65 °C. to achieve better heat exchanger performance, the experimental results will be compared to those obtained when using pure water. The improvement in performance with Nanofluid as a working fluid was discovered during experiment analysis. (40%) maximum heat exchanger effectiveness obtained at Nanofluid flow rate of 2 L/min has (0.5%) volume concentration ,effectiveness (54%) at (1%) a volume concentration.

Impact of hole cleaning and drilling performance on the equivalent circulating density

Efficient hole cleaning in drilling operations is essential to ensure optimum penetration rates. This complex problem involves the simultaneous analysis of multiple parameters, including cuttings characteristics, fluid rheology, and annulus space geometry. The effect of the mud density increase due to the cuttings concentration, which itself is a function of the settling velocity and rate of penetration (ROP), must be considered for accurate calculations of the equivalent circulation density (ECD).Mechanical Specific Energy (MSE) models have been widely used in bit selection, drilling efficiency quantification, drilling performance monitoring, drilling performance optimization, and ROP improvement. We attempted to employ MSE for optimized hole cleaning and controlled ECD. Cuttings concentration was integrated with the drilling MSE, which was calculated to determine the effect of different drilling parameters on hole cleaning and ECD. We proposed a new model for predicting the ECD in vertical and deviated wellbores that takes fluid and formation properties, as well as wellbore and drill string geometry and drilling operational parameters, into account. The model predicts the cuttings concentration and equivalent circulation density in vertical and deviated wells. The workflow implements the critical and settling velocity models, which aids in optimizing drilling performance and hole cleaning. The developed model was used to study the effect of different drilling parameters on ECD and help engineers optimize their operational parameters. Integrating the drilling operational parameters to provide controlling options to drillers as they monitor ECD values while maintaining safety and optimizing the drilling job is critically important.

Evaluation of circulating temperature in wellbores using drilling microchips: Modeling and case studies

Using cost-effective drilling microchips to collect real-time temperature distribution while drilling is advantageous to accurately predict the variation of drilling fluid density and rheological parameters in wellbore. This study introduces a methodology for analysis of measured temperature of drilling microchips. Multiple sets of drilling microchips were deployed into two wells to measure the distribution of circulating temperature in tubular and annular space. An iterative algorithm is developed to calibrate the time-scale of drilling microchips to depth-scale considering variable pump rates, transit times and slippage of drilling microchips. A transient thermal model is modified to simulate the variation of wellbore temperature during circulation of tracers. It is shown that the velocity of tracers in each interval depends on the flow regime and rheological properties of drilling fluid. Comparing the predicted and actual transit times of tracers, it is realized that the maximum fluid velocity in each interval is a better choice to represent the velocity of tracers. It is shown that predictions of the transient model strongly depend on temperature distribution of the wellbore prior to deployment of tracers. This study provides new insights about the temperature distribution in wellbore while drilling and elaborates on the necessity to address the transient processes particularly during startups in wells with critical downhole conditions.

Numerical Simulation of Effective Hole Cleaning by Using an Innovative Elliptical Drillpipe in Horizontal Wellbore

In the drilling of horizontal wells, the drill cuttings tend to settle down on the low side of the annulus due to gravity and form a stationary bed, which results in hole cleaning problems. In this paper, a novel type of drillpipe with an elliptical shape was proposed to alleviate inadequate hole cleaning during the drilling of horizontal wells. A three-dimensional computational fluid dynamic (CFD) Eulerian-Eulerian approach with the Realizable k-ɛ turbulence model was developed to predict the solid–liquid two-phase flow in the annular space. Numerical examples were given to investigate the influence of different parameters on cuttings’ transport behavior, and the elliptical drillpipe was compared with the circular drillpipe. The annular cuttings concentration, annular pressure drop, and hole cleaning efficiency were evaluated. The numerical results clarify the potential of the elliptical drillpipe to enhance the hole cleaning efficiency without significantly increasing the annular pressure drop. Due to the swirl flow and secondary flow caused by the rotation of the curvature wall, the swaying phenomenon of drill cuttings’ distribution along the rotation direction of drillpipe was observed and enhanced the cuttings transport ability. Using the elliptical drillpipe as a joint-type tool can improve hole cleaning performance. Under the optimum conditions applied in this study, the hole cleaning efficiency increased by nearly 18%.

Numerical Study of Heat Transfer by Natural Convection in Concentric Hexagonal Cylinders Charged with a Nanofluid

In this document, a numerical study of the natural convection of steady-state laminar heat transfer in a horizontal ring between a heated hexagonal inner cylinder and a cold hexagonal outer cylinder. A Cu - water nanofluid traverses this annular space. The system of equations governing the problem was solved numerically by the fluent calculation code based on the finite volume method. Based on the Boussinesq approximation. The interior and exterior sides from the two cylinders are maintained at a fixed temperature. We investigated the impacts of various thermal Rayleigh numbers (103≤ Rat ≤2.5x105), and the volume fraction from the nanoparticles (0≤ Ø ≤0.12) on fluid flow and heat transfer performance. It is found that in high thermal Rayleigh numbers, a thin thermal boundary layer is illustrated at the flow that heavily strikes the ceiling and lower from the outer cylinder. In addition, the local and mean Nusselt number from a nanofluid are enhanced by enhancing the volume fraction of the nanoparticles.The results are shown within the figure of isocurrents, isotherms, and mean and local Nusselt numbers. Detailed results of the numerical has been compared with literature ones, and it gives a reliable agreement.

Natural Convection in Annulus Between Two Concentric Cylinders Partially Filled with Metal Foam Distributed with New Suggested Design

The investigation of natural convection in an annular space between two concentric cylinders partially filled with metal foam is introduced numerically. The metal foam is inserted with a new suggested design that includes the distribution of metal foam in the annular space, not only in the redial direction, but also with the angular direction. Temperatures of inner and outer cylinders are maintained at constant value in which inner cylinder temperature is higher than the outer one. Naiver Stokes equation with Boussinesq approximation is used for fluid regime while Brinkman-Forchheimer Darcy model used for metal foam. In addition, the local thermal equilibrium condition in the energy equation of the porous media is presumed to be applicable for the present investigation. CFD ANSYS FLUENT software package (version 18.2) is used as a solver to this problem. Various parameters are examined; Rayleigh number, Darcy number, and thermal conductivity ratio to study the effect of them on fluid flow and heat transfer inside the annuli space in the suggested design of metal foam layer. current model is compared with the available published results and good agreement is noticed. Results showed that as Rayleigh number increases the dominated of convection mode increases and Nusselt increases. Also, Nusselt is larger at the higher Darcy and thermal conductivity ratio. It was found that at Rayleigh of 106 and thermal conductivity ratio of 104 Nusselt reach its higher value which is 6.69 for Darcy of 0.1 and 6.77 for Darcy of 0.001. A comparison between this design and the traditional design was established for Darcy 0.001 and thermal conductivity ratio 102, and its showed a good enhancement in Nusselt number and the greatest enhancement percentage was 44% at Rayleigh equal 5*104 while the lowest percentage is 6% for Rayleigh equal106.

Circulating preheating model of full-length horizontal wellbore in heavy oil reservoirs with multiple thermal fluid injection

Heavy oil reservoirs are rich in resources and have broad prospects for exploration and development. Wellbore heat transfer is one of the important areas of heavy oil research. However, the current research on the preheating of multi-element thermal fluid circulation in the wellbore is still insufficient. Based on thermodynamic equations and fluid dynamics equations, this paper establishes a cyclic preheating model of multi-element thermal fluid in the wellbore. The model considers the mixing characteristics of superheated steam and non-condensed gas, and is applicable to both vertical and horizontal wellbores. Results show that the temperature curve can be divided into four parts: the temperature of the inner tube in the vertical section of the wellbore, the temperature of the inner tube in the horizontal section of the wellbore, the temperature of the annular space in the horizontal section of the wellbore, and the temperature of the annular space in the vertical section of the wellbore; In the horizontal section of the wellbore, the multi-element thermal fluid in the inner tube releases heat energy into the annular space, and there is a large temperature difference at the heel end and a small temperature difference at the toe end.

Double-diffusive natural convection in a cavity with an inner cylinder wrapped by a porous layer

This paper reports a numerical study of double-diffusive natural convection through an annular space delimited by a square cylinder on the outside and a cylindrical cylinder on the inside covered by a porous layer. The Darcy-Brinkmann-Forchheimer is used for modeling flow in both fluid and porous areas. The annular space is partially or completely filled with an isotropic porous medium. A finite volume method, using the Patankar-Spalding technique is used for solving the discretization of the dimensionless equations governing the problem. The effects of simultaneously applied thermal and solutal buoyancy forces on heat and mass transfer are shown in the results for a large range of buoyancy ratios, Rayleigh number, and thermal conductivity. Streamlines, isotherms, and iso-concentrations are presented to analyze the flow structure transition from mass species dominated to thermal dominated flow. Results show that the buoyancy ratio can change the flow pattern and the increased thermal conductivity ratio can improve heat and mass transfer. A good agreement was obtained between the present results and those published were found.

Displacement flow of yield stress materials in annular spaces of variable cross section

We conducted an experimental study of a yield stress material being displaced upwardly at controlled flow rate by a Newtonian fluid in an annular space whose external wall consists of a sudden expansion–contraction. This system is a simplified representation of the primary cementing process of an oil well, whose bore diameter may present variations. In the experiments, different pairs of fluids were employed. The yield stress materials were Carbopol aqueous solutions at three different weight concentrations, with Herschel–Bulkley viscosity behavior. The Newtonian liquid was a glycerin/water mixture. A wide range of flow rates were explored, varying the dimensionless cavity depth and cavity axial length. A non-monotonic behavior is observed for the dimensionless volume of yield stress material displaced from the cavity by the Newtonian fluid flow. In addition, the rheological properties and geometrical parameters were seen to have a strong influence on the displaced volume.

THE EFFECT OF AL2O3 NANOPARTICLES SPHERICITY ON HEAT TRANSFER BY FREE CONVECTION IN AN ANNULAR METAL-BASED POROUS SPACE BETWEEN VERTICAL CYLINDERS SUBMITTED TO A DISCRETE HEAT FLUX

In the present study, the transferred thermal heat by the phenomenon of free convection flow in an annular metal-base porous space inside two vertical concentric cylinders saturated by a (Al2O3-water) nanofluid with different shapes of nanoparticles (NPs) has been numerically investigated. The finite difference method is used to solve the governing system of equations. The outer cylinder is kept at constant temperature, and the discrete heat flux and the unheated adiabatic sections are placed on the inner cylinder. The base walls are insulated and impermeable. The obtained results of the numerical simulation are presented to exhibit the consequences of various parameters, such as the Rayleigh number (RaTh), Darcy number (Da), porosity (ε), solid NPs volume fraction (φ), and the shape of NPs as well as the conductivity ratio of porous media (λ). It is observed that the transferred thermal flux increases as the conductivity ratio of porous media increases. The results obtained also show an improvement of the rate of heat transfer with the increase in Darcy number, Rayleigh number, and NPs volume fraction. Furthermore, a significant improvement in the overall heat transfer has been found with oblate and prolate alumina (Al2O3) spheroid NPs.

Experimental set up for the investigation of partial phase changes of phase change materials

Thermal energy storage with phase change materials (PCMs) has attracted a lot of attention in the last several decades. Most PCMs do not change phase at a constant temperature but rather in a certain temperature range. It means that the PCM need to transit through its phase change temperature range to fully change phase from the solid state to the liquid state and vice-versa. The situation, in which the phase transition begins and/or ends within the phase change temperature range (in the mushy zone), is usually called a partial phase transition (or a partial phase change). The partial phase transitions occur quite often in real-life thermal energy storage systems with PCMs; especially when a PCM has a wide phase change temperature range. The behavior of PCMs during the partial phase transitions is poorly understood at the moment, because the experimental techniques used for the characterization of PCMs (such as the differential scanning calorimetry – DSC) are difficult to apply for the study of partial phase transitions. The lack of knowledge in this area influences the accuracy of phase change simulation models. The main goal of the experimental investigations, described in the paper, was to obtain data for the development of a simulation model for partial phase changes. The experimental set up for the investigation of partial phase changes of PCMs has been proposed, assembled, and the pilot measurements have been conducted. The experimental set up consists of two water storage tanks (that can be maintained at different water temperatures), a water-PCM concentric tube type heat exchanger and a data acquisition system. The water flows through the central tube of the heat exchanger while the PCM is located in the annular space of the exchanger. The water storage tanks, maintained at the temperatures within the phase change temperature range of a PCM, allow for the investigations of the heat storage cycles consisting of partial phase changes.

Experimental study on boiling heat transfer in negative-pressure flowing water in a vertical annular tube

To study energy recovery from low temperature wastewater during industrial production, a water-boiling heat transfer experimental device was built. A casing evaporator with a length of 1450 mm, an inner tube diameter of 30 mm, and an annular space gap of 14.2 mm is taken as the main research object. The boiling heat transfer characteristics of water in the annular tube area of the casing evaporator were experimentally studied by adjusting the inlet temperature (60? 85?C) of hot water and the pressure in the annular tube (12.1-57.6 kPa). The results show that, as the pressure of the system decreases, the boiling phenomenon in the annular tube becomes more intense and the convective heat transfer coeffi-cient increases. The boiling flow and average surface convective heat transfer enhancement rates, ? , were 2.2 and 1.5 when an initial pressure of 1 kPa was used. When the flow rate of the working medium in the annular tube was 1.69 kg?m2/s, the convective heat transfer coefficient gradually increased with the temperature and then stabilized when the inlet temperature reached between 80?C and 85?C. These results reveal the characteristics of boiling-water heat transfer in an annular tube and aid in the design of heat pipe systems for waste-heat recovery.

Numerical Analysis of the Effect of Porous Structure On Free Convection Heat Transfer Inside an Eccentric Annular Space

Numerical Analysis of the Effect of Porous Structure On Free Convection Heat Transfer Inside an Eccentric Annular Space

Improvement of mud displacement from the annular space of the borehole in terms of the criterion of selecting washing fluids and pre-flushes

One of the most important steps in drilling the well is cementing the annular space between casing and rock formations. This process is significant because of the stabilization of the well and effectively separation of the consecutive rock horizons. It is required that cementing ensures durable and effective insulation of the rock mass. The complete displacement of the drilling fluid from the annular space is particularly important due to a number of negative phenomena related to its insufficient extrusion. The cement slurry pressed through the annular space displaces the mud but is not able to sufficiently thoroughly remove the residue left behind. The subject of the laboratory research was to check how selected washer affect the efficiency of displacing drilling fluid from the annular space of the borehole. In addition, the tests included the determination of the optimal washing time and the optimal pumping rate of the washing fluid. Moreover, the tests included the determination of the optimal washing time and the optimal pumping rate of the washing fluid.

Improvement of acid treatment with the sintanol preparation after hydro-sand blasting of wells in the conditions of ANK «Bashneft»

A sandblasting hammer is lowered into the well, setting against the selected processing interval, and hydraulic clamps are necessary for the rig to be held firmly. The displacement of the latter eliminates the possibility of selective processing. After the usual sandblasting and flushing the well from sand, without changing the position of the perforator, an acid solution is pumped into the pipes, which, entering the channel formed, is filtered through its walls into the treated section of the formation. The part of the acid that, after the end of the treatment, has accumulated in the wellbore, is forced into the reservoir by the squeezing fluid through the annular space. Increase the acid depletion time, i.e. slow down the reaction rate by adding special reagents to the solution. So, a syntanol DS-10 TU 2483-016-71150986-2012 (a non-ionic surfactant and is intended for use as an effective surfactant) is a very effective reaction rate reducer. Adding it in an amount of 0.5% (by weight of the volume of the solution) can reduce the reaction rate by 2.7 times. Keywords: speed; reaction; syntanol; processing; pressure.

Parameter substantiation of supra bit jet pump for productive formation opening

The purpose of the study is to develop a supra bit jet pump taking into account the unsteadiness of low-speed drilling for crushing the cuttings injected from the annular space under productive formation opening. The article proposes a device for drill string bottom assembly intended for the initial opening of the productive formation. The device includes a supra bit jet pump and a colmatator. The jet pump creates an additional circulation loop of the drilling fluid above the well bottom, crushes the cuttings injected from the annular space in the mixing chamber and delivers it to the colmatator. An additional circulation loop above the well bottom creates a local drawdown of the formation while maintaining the hydrostatic pressure in the well. Crushing of cuttings in the mixing chamber of the jet pump occurs due to the creation of cross flows in the jet pump. The cross flows are provided due to the angular and eccentric displacement of the working nozzle of the jet pump relative to the mixing chamber. The colmatator creates an impermeable screen on the borehole wall for temporary isolation of the productive formation under initial opening. The conducted study allowed the authors to propose head characteristics of the jet pump taking into account the angular, eccentric displacement of the working nozzle. The head characteristic of the jet pump has been developed for the unsteady operation of the jet pump in the drill string bottom assembly. The head characteristics take into account the roughness of the flow path of the jet pump. Using the head characteristics, the permissible displacements of the working nozzle of the jet pump have been determined. Recommendations for the design of jet pumps for drill string bottom assemblies are proposed.

Studying joint influence of a number of factors on borehole cleaning

Studying the behavior of cuttings transport under various conditions using experimental observations and computational fluid dynamics is the main method for analyzing the influence of cuttings, fluid and operating parameters on well cleaning. Despite the existing abundant models and recommendations of researchers, still there are problems with the accuracy of determining the cuttings layer height, critical velocity and other key parameters, which complicates the task of effective solution of the problem of borehole cleaning. The purpose of the study is to analyze the models obtained via the organization of a full factorial experiment and variance analysis to identify the influence of such factors as viscosity and flow rate of the drilling fluid in the annular space and the inclination angle of the well on the degree of cuttings transport. The studies of the kind are carried out using special devices called flow loops. Experimental data were taken from literature sources. To organize a full factorial experiment, the data of the dependent variable were combined into a combinational square, which simplified the coding of factor values. After setting the full factorial experiment, the models were obtained that made it possible to assess the contribution of the studied factors to the process of destruction product removal within the intervals determined while setting the research tasks. The obtained models allowed to determine the influence degree of each of the factors on the process under investigation. The results of the succeeding analysis of variance confirmed the indicated degree of influence and determined the rank of each of the factors in percentage.

Photocatalytic Degradation of Dissolved Phenol by Immobilized Zinc Oxide Nanoparticles: Batch Studies, Continuous Flow Experiments, and Numerical Modeling.

In spite of the progress achieved on the photo-catalytic treatment of water streams, there is still a gap of knowledge on the optimization of the performance of continuous-flow photo-reactors. Zinc-oxide (ZnO) nanoparticles were immobilized on Duranit (80% silica + 20% alumina) inert balls with dip-coating and thermal annealing. The immobilized ZnO nanoparticles were characterized by scanning electron microscopy (SEM), energy dispersive X-ray analysis (EDX), X-ray diffraction (XRD), ultraviolet-visible (UV-Vis) spectroscopy, and Raman spectroscopy. To assess the stability and photocatalytic capacity of immobilized ZnO, degradation tests of phenol were performed in batch mode in a 22 W UV-oven with an emission peak at 375 nm by varying the temperature, the initial phenol concentration, and the ratio of photocatalyst mass to initial phenol mass. Continuous flow tests were conducted on two types of annular photo-reactors, made of poly(methyl)methacrylate (PMMA) and stainless steel (STST), equipped with a 6 W UV-lamp with emission at 375 nm, packed with ZnO-coated Duranit beads. Experiments were conducted by recirculating the phenol solution between the annular space of reactor and an external tank and varying the flow rate and the liquid volume in the tank. A one-dimensional dynamic mathematical model was developed by combining reactive with mass-transfer processes and used to estimate the overall reaction kinetic constant with inverse modeling. The results revealed that the ZnO losses might be discernible in batch mode due to the intense stirring caused by the bubbles of injected air, while an insignificant loss of ZnO mass occurs under continuous flow conditions, even after several cycles of reuse; the order of the overall phenol photodegradation reaction is lower than unity; the pseudo-1st order kinetic constant scales positively with the ratio of photocatalyst mass to the initial phenol mass and Peclet number.