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I A Frigaard - One of the best experts on this subject based on the ideXlab platform.
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buoyancy effects on turbulent displacement of viscoplastic Fluids from strongly eccentric horizontal annuli
Physics of Fluids, 2020Co-Authors: Majid Bizhani, I A FrigaardAbstract:We present an experimental and numerical study of the turbulent displacement of viscoplastic Fluids in a horizontal eccentric annulus. Several experiments where a weighted Newtonian Fluid displaces a yield stress Fluid under a turbulent flow condition are presented and discussed. These are also used to validate the turbulent displacement model that we use in this study. The model simulator is used to study the mechanisms by which buoyancy influences turbulent displacement in more detail and outside of the range of our experiments. Extreme cases where the generated wall shear stress of the displacing Fluid is smaller than the yield stress of the Displaced Carbopol are investigated. The results show that buoyancy is ineffective in countering the tendency of the Fluid to disperse along the wide gap of the annulus. In both model and experiment, the outcome of the displacement appears to be controlled by the yield stress of the in situ Fluid and the eccentricity of the annulus. For fully turbulent flows, the viscosity of the Displaced Fluid has a negligible effect, and having also negated buoyancy, there appears to be no mechanism to stabilize the turbulent displacement of a yield stress Fluid in a severely eccentric horizontal annulus. For the underlying industrial process, this means that extreme caution should be used in designing turbulent flow displacements for horizontal wells. There are two solutions: (i) increase the flow rate to generate sufficient stresses (usually not possible due to pump and formation fracture pressure limits) and (ii) ensure a better centralized annulus (unpopular because of operational constraints).
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turbulent displacement flow of viscoplastic Fluids in eccentric annulus experiments
Physics of Fluids, 2020Co-Authors: Majid Bizhani, Yasaman Foolad, I A FrigaardAbstract:We study displacement flows in strongly eccentric annuli, where the in situ Fluid is viscoplastic and the displacing Fluid is Newtonian. This mimics the situation found in the cementing of horizontal oil and gas wells. In this configuration, it is common that the yield stress of the Displaced Fluid prevents displacement from the narrow side of the annulus, where it remains static. We address the question of whether a turbulent flow of the displacing Fluid will be effective in removing the static narrow side channel and by what means. The flows proceed with rapid displacement along the wide side of the annulus, leaving behind a gelled channel of Fluid on the narrow side. The narrow side is Displaced either slowly or not at all. This depends on both the yield stress of the Displaced Fluid and the turbulence characteristics of the displacing Fluid. We influence the latter through the use of drag-reducing polymers. We show that secondary flows in the turbulent displacing Fluid are essential to the displacement and also the increased pressure drops in the turbulent flow. We hypothesize that the displacement is enhanced by the transmission of normal stresses into the gelled layer.
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buoyancy effects on micro annulus formation density stable displacement of newtonian bingham Fluids
Journal of Non-newtonian Fluid Mechanics, 2017Co-Authors: M Zare, A Roustaei, I A FrigaardAbstract:Abstract Buoyant miscible displacement flow of a Bingham Fluid by a Newtonian Fluid along a vertical plane-channel is studied, in the high Peclet number regime. The displacing Fluid is denser than the Displaced Fluid and the flow direction is density-stable (upwards). The flow is effectively governed by 4 dimensionless parameters: the Newtonian Bingham number (BN), the viscosity ratio (m), the Reynolds number (Re), and modified Froude number (Fr). This is a simple model for micro-annulus formation in the primary cementing of oil and gas wells. We show that the residual layer thickness is largely determined by two parameters: (BN/m, χ*/m), where χ * = 2 R e F r 2 . Residual wall layers may be either static or mobile, and mobile layers either evolve to become static or are washed from the channel at long times. We show that the different behaviours of the residual layers are linked to different characteristic behaviours of the displacement front, and we show how the latter behaviours can be predicted using a lubrication/thin-film approximation.
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miscible heavy light displacement flows in an inclined two dimensional channel a numerical approach
Physics of Fluids, 2014Co-Authors: K Alba, Seyed Mohammad Taghavi, I A FrigaardAbstract:We numerically study the displacement flow of two iso-viscous Newtonian Fluids in an inclined two-dimensional channel, formed by two parallel plates. The results are complementary to our previous studies on displacement flows in pipes and channels. The heavier displacing Fluid moves the lighter Displaced Fluid in the downward direction. Three dimensionless groups largely describe these flows: the densimetric Froude number (Fr), the Reynolds number (Re), and the duct inclination (β). As a first order approximation, we are able to classify different flow regimes phenomenologically in a two-dimensional (Fr; Recosβ/Fr)-plane and provide leading order expressions for the transitions between different regimes. The stabilizing and/or de-stabilizing effects of the imposed mean flow on buoyant exchange flows (zero imposed velocity) are described for a broad range of dimensionless parameters.
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miscible density stable displacement flows in inclined tube
Physics of Fluids, 2012Co-Authors: K Alba, Seyed Mohammad Taghavi, I A FrigaardAbstract:We study the displacement flow of two Newtonian Fluids in an inclined pipe. The Fluids have the same viscosity but different densities. The displacing Fluid is denser than the Displaced Fluid and is placed above the Displaced Fluid (i.e., a density-unstable configuration). Three dimensionless groups describe these flows: a densimetric Froude number Fr, a Reynolds number Re, and the pipe inclination β. Our experiments cover fairly broad ranges of these parameters: 0 ⩽ Fr ⩽ 9; 0 ⩽ Re ⪅ 2400; 0 ⩽ β ⩽ 85°. Phenomenologically, our experimental flow observations vary from well mixed fully diffusive regimes, through buoyancy-dominated inertial exchange regimes, to laminar viscous flows, all with varying degrees of stability. We characterize the different flow regimes observed in terms of the three dimensionless groups and provide leading order approximations to the velocity of the displacement front and the macroscopic diffusion in each regime.
Seyed Mohammad Taghavi - One of the best experts on this subject based on the ideXlab platform.
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buoyant miscible displacement flows in vertical pipe
Physics of Fluids, 2016Co-Authors: Amin Amiri, F Larachi, Seyed Mohammad TaghaviAbstract:The displacement flow of two miscible Newtonian Fluids is investigated experimentally in a vertical pipe of long aspect ratio (δ−1 ≈ 210). The Fluids have a small density difference and they have the same viscosity. The heavy displacing Fluid is initially placed above the light Displaced Fluid. The displacement flow is downwards. The experiments cover a wide range of the two dimensionless parameters that largely describe the flow: the modified Reynolds number (0 ≤ Ret⪅800) and the densimetric Froude number (0 ≤ Fr ≤ 24). We report on the stabilizing effect of the imposed flow and uncover the existence of two main flow regimes at long times: a stable displacement flow and an unstable displacement flow. The transition between the two regimes occurs at a critical modified Reynolds number RetCritical, as a function of Fr. We study in depth the stable flow regime: First, a lubrication model combined with a simple initial acceleration formulation delivers a reasonable prediction to the time-dependent penetratin...
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miscible heavy light displacement flows in an inclined two dimensional channel a numerical approach
Physics of Fluids, 2014Co-Authors: K Alba, Seyed Mohammad Taghavi, I A FrigaardAbstract:We numerically study the displacement flow of two iso-viscous Newtonian Fluids in an inclined two-dimensional channel, formed by two parallel plates. The results are complementary to our previous studies on displacement flows in pipes and channels. The heavier displacing Fluid moves the lighter Displaced Fluid in the downward direction. Three dimensionless groups largely describe these flows: the densimetric Froude number (Fr), the Reynolds number (Re), and the duct inclination (β). As a first order approximation, we are able to classify different flow regimes phenomenologically in a two-dimensional (Fr; Recosβ/Fr)-plane and provide leading order expressions for the transitions between different regimes. The stabilizing and/or de-stabilizing effects of the imposed mean flow on buoyant exchange flows (zero imposed velocity) are described for a broad range of dimensionless parameters.
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miscible density stable displacement flows in inclined tube
Physics of Fluids, 2012Co-Authors: K Alba, Seyed Mohammad Taghavi, I A FrigaardAbstract:We study the displacement flow of two Newtonian Fluids in an inclined pipe. The Fluids have the same viscosity but different densities. The displacing Fluid is denser than the Displaced Fluid and is placed above the Displaced Fluid (i.e., a density-unstable configuration). Three dimensionless groups describe these flows: a densimetric Froude number Fr, a Reynolds number Re, and the pipe inclination β. Our experiments cover fairly broad ranges of these parameters: 0 ⩽ Fr ⩽ 9; 0 ⩽ Re ⪅ 2400; 0 ⩽ β ⩽ 85°. Phenomenologically, our experimental flow observations vary from well mixed fully diffusive regimes, through buoyancy-dominated inertial exchange regimes, to laminar viscous flows, all with varying degrees of stability. We characterize the different flow regimes observed in terms of the three dimensionless groups and provide leading order approximations to the velocity of the displacement front and the macroscopic diffusion in each regime.
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buoyant miscible displacement flows at moderate viscosity ratios and low atwood numbers in near horizontal ducts
Chemical Engineering Science, 2012Co-Authors: Seyed Mohammad Taghavi, K Alba, I A FrigaardAbstract:Abstract We present results from a study of buoyant miscible displacements flows at moderate viscosity ratios in near-horizontal ducts. Low Atwood numbers are considered. Inertial effects are significant although the flow regimes are laminar. Pipe and plane channel geometries are considered using a mix of experimental, computational and analytical techniques. The main focus of the study is on the effects of the viscosity ratio between the Fluids. We show that small viscosity ratios lead to more efficient displacements, as is intuitive. In each geometry we find a mix of viscous and inertial flows, in broadly the same pattern as for the iso-viscous displacements studied extensively in Taghavi et al. (submitted for publication) . Predictive models are proposed for the viscous regime, in the case of the plane channel, and for the inertial exchange flow regime, in both geometries. We also study displacement flows with shear-thinning Fluids, over a more restrictive range of parameters. We show that with an appropriate definition of the effective viscosity the scaled front velocities fit well with the results from the Newtonian displacements, in both pipe and plane channel geometries. The main role of ratio m of Displaced Fluid viscosity to displacing viscosity is in line with our intuition. For m > 1 displacement efficiencies are reduced and the front velocities are larger. However, the main increase in front velocity is achieved for modest viscosity ratios of 3 or 4 to 1, with little increase afterwards. The reverse situation, m 1 , shows significant improvements in displacement efficiency, with front velocity V ^ f reduced down towards the imposed mean velocity V ^ 0 , as m decreases. A viscosity ratio of around 1–4 appears to achieve quite efficient displacements, and to be able to compensate for the effects of buoyancy (which in our case are always destabilising).
Roney L Thompson - One of the best experts on this subject based on the ideXlab platform.
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residual mass and flow regimes for the immiscible liquid liquid displacement in a plane channel
International Journal of Multiphase Flow, 2011Co-Authors: Jackson F Freitas, Edson J Soares, Roney L ThompsonAbstract:Abstract The motion of two immiscible liquids in a plane channel is analyzed for the case in which the flow conditions and the interactions between the liquids and the solid surface maintain the Displaced Fluid attached to the wall. The Galerkin Finite Element Method is used to compute the velocity field and the configuration of the interface between the two Fluids. We compare the residual mass fraction left on the wall with its two counterparts in capillary tubes, namely residual mass fraction and dimensionless layer thickness of the Displaced Fluid. The main result of this comparison was that although there is a qualitative similarity concerning the layer thickness between the two cases, the residual fraction of mass presented an important difference, showing that when the aspect ratio of the capillary passage is large there is an increase in the displacement efficiency. The thickness of the Displaced liquid film attached to the channel walls is a function of the capillary number (Ca) and the viscosity ratio (Nμ). A map of streamlines in the Cartesian space (Ca, Nμ) with the different flow regimes of the problem is presented. We also showed that we can adapt the available analytical results obtained for gas-displacement in capillary tubes to the plane channel case, for low values of Ca.
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flow regimes for the immiscible liquid liquid displacement in capillary tubes with complete wetting of the Displaced liquid
Journal of Fluid Mechanics, 2009Co-Authors: Edson J Soares, Roney L ThompsonAbstract:The motion of two immiscible liquids in a capillary tube is analysed, theoretically and numerically, for the case in which a residual film confines the displacing liquid to the core of this tube. The theoretical analysis has shown that the three flow regimes predicted by Taylor ( J. Fluid Mech ., vol. 10, 1961, pp. 161–165), for the case of gas-displacement, can only be achieved when the ratio of the viscosity of the Displaced Fluid to that of the displacing one is greater than 2. An elliptic mesh generation technique, coupled with the Galerkin finite-element method, is used to compute the velocity field and the configuration of the interface between the two Fluids. A map of cases in the Cartesian space defined by the capillary number ( Ca ) and the viscosity ratio ( N μ ) is constructed in order to locate the different flow patterns the problem exhibits. The critical capillary number at which the flow enters the transition range between the bypass regime and the full-recirculating one is given. While a decrease of the fraction of mass attached to the wall is achieved by decreasing Ca or increasing N μ , bypass flow patterns are formed as a consequence of high values of the capillary number and viscosity ratio.
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numerical investigation on gas displacement of a shear thinning liquid and a visco plastic material in capillary tubes
Journal of Non-newtonian Fluid Mechanics, 2007Co-Authors: Dione A De Sousa, Edson J Soares, Rogerio Silveira De Queiroz, Roney L ThompsonAbstract:Abstract An elliptic mesh generation technique, with the Galerkin Finite Element Method is used to compute the free surface of the two-phase flow problem of a gas displacing a non-Newtonian material in a capillary tube. Two classes of non-Newtonian materials were investigated: a power-law shear-thinning liquid and a visco-plastic material with the viscosity function proposed by Papanastasiou [T.C. Papanastasiou, Flows of materials with yield-stress, J. Rheol. 31 (1987) 385–404]. The results were given as a function of a non-Newtonian capillary number and a rheological dimensionless parameter: the behavior index in the shear-thinning liquid case and a dimensionless yield-stress (equivalent to Bingham number) in the visco-plastic material. The goal of the present work is to study flow patterns, configuration of the interface between the two phases, and fraction of the mass of non-Newtonian material deposited at the wall, as functions of the dimensionless numbers cited. Some general results of experimental and numerical works found in literature were reproduced with a quite good agreement and a wider range of the dimensionless numbers was investigated. In both classes of materials studied, as the Displaced Fluid departs from Newtonian behavior, the fraction of the mass deposited on the tube wall decreases and the shape of the interface becomes flatter. It was offered a plausible explanation for this counter-intuitive result related to visco-plastic Fluid, i.e. an apparent increase of its viscosity (increasing the dimensionless yield-stress number), induces a decrease of the layer thickness left behind. Concerning flow patterns, it was possible to identify ranges, dependent on rheological properties and capillary number, where the transition between bypass flows and fully recirculating flows occurs. In the Newtonian case all the flow patterns predicted by Taylor [G.I. Taylor, Deposition of a viscous Fluid on the wall a tube, J. Fluid Mech. 10 (1961) 161–165] were well captured. In the visco-plastic and pseudo-plastic case it was found an interesting type of intermediate flow regime which is not present in the Newtonian transition.
Howard A Stone - One of the best experts on this subject based on the ideXlab platform.
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axisymmetric flows from Fluid injection into a confined porous medium
Physics of Fluids, 2016Co-Authors: O Guo, Zhong Zheng, Michael A Celia, Howard A StoneAbstract:We study the axisymmetric flows generated from Fluid injection into a horizontal confined porous medium that is originally saturated with another Fluid of different density and viscosity. Neglecting the effects of surface tension and Fluid mixing, we use the lubrication approximation to obtain a nonlinear advection-diffusion equation that describes the time evolution of the sharp Fluid-Fluid interface. The flow behaviors are controlled by two dimensionless groups: M, the viscosity ratio of Displaced Fluid relative to injected Fluid, and Γ, which measures the relative importance of buoyancy and Fluid injection. For this axisymmetric geometry, the similarity solution involving R2/T (where R is the dimensionless radial coordinate and T is the dimensionless time) is an exact solution to the nonlinear governing equation for all times. Four analytical expressions are identified as asymptotic approximations (two of which are new solutions): (i) injection-driven flow with the injected Fluid being more viscous tha...
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flow regimes for Fluid injection into a confined porous medium
Journal of Fluid Mechanics, 2015Co-Authors: Zhong Zheng, O Guo, Michael A Celia, Iva C Christov, Howard A StoneAbstract:We report theoretical and numerical studies of the flow behaviour when a Fluid is injected into a confined porous medium saturated with another Fluid of different density and viscosity. For a two-dimensional configuration with point source injection, a nonlinear convection–diffusion equation is derived to describe the time evolution of the Fluid–Fluid interface. In the early time period, the Fluid motion is mainly driven by the buoyancy force and the governing equation is reduced to a nonlinear diffusion equation with a well-known self-similar solution. In the late time period, the Fluid flow is mainly driven by the injection, and the governing equation is approximated by a nonlinear hyperbolic equation that determines the global spreading rate; a shock solution is obtained when the injected Fluid is more viscous than the Displaced Fluid, whereas a rarefaction wave solution is found when the injected Fluid is less viscous. In the late time period, we also obtain analytical solutions including the diffusive term associated with the buoyancy effects (for an injected Fluid with a viscosity higher than or equal to that of the Displaced Fluid), which provide the structure of the moving front. Numerical simulations of the convection–diffusion equation are performed; the various analytical solutionsmore » are verified as appropriate asymptotic limits, and the transition processes between the individual limits are demonstrated.« less
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the influence of the gas phase on liquid imbibition in capillary tubes
Journal of Fluid Mechanics, 2011Co-Authors: Marcus Hultmark, Jeffrey M Aristoff, Howard A StoneAbstract:The imbibition of liquid into a capillary tube is studied both theoretically and experimentally for sufficiently long tubes where viscous resistance from the gas phase ahead of the moving front is significant. At early times, and as the length of the tube is increased, we observe a systematic deviation from classical theory that cannot be attributed to the inertia of the liquid nor entrance effects. Instead, this behaviour is rationalized by considering the viscous resistance from the gas as it is Displaced by the liquid. An explicit analytical solution for a one-dimensional description of the flow is given that accounts for viscous resistance from the Displaced Fluid. Excellent agreement between experiment and theory is obtained.
K Alba - One of the best experts on this subject based on the ideXlab platform.
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miscible heavy light displacement flows in an inclined two dimensional channel a numerical approach
Physics of Fluids, 2014Co-Authors: K Alba, Seyed Mohammad Taghavi, I A FrigaardAbstract:We numerically study the displacement flow of two iso-viscous Newtonian Fluids in an inclined two-dimensional channel, formed by two parallel plates. The results are complementary to our previous studies on displacement flows in pipes and channels. The heavier displacing Fluid moves the lighter Displaced Fluid in the downward direction. Three dimensionless groups largely describe these flows: the densimetric Froude number (Fr), the Reynolds number (Re), and the duct inclination (β). As a first order approximation, we are able to classify different flow regimes phenomenologically in a two-dimensional (Fr; Recosβ/Fr)-plane and provide leading order expressions for the transitions between different regimes. The stabilizing and/or de-stabilizing effects of the imposed mean flow on buoyant exchange flows (zero imposed velocity) are described for a broad range of dimensionless parameters.
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miscible density stable displacement flows in inclined tube
Physics of Fluids, 2012Co-Authors: K Alba, Seyed Mohammad Taghavi, I A FrigaardAbstract:We study the displacement flow of two Newtonian Fluids in an inclined pipe. The Fluids have the same viscosity but different densities. The displacing Fluid is denser than the Displaced Fluid and is placed above the Displaced Fluid (i.e., a density-unstable configuration). Three dimensionless groups describe these flows: a densimetric Froude number Fr, a Reynolds number Re, and the pipe inclination β. Our experiments cover fairly broad ranges of these parameters: 0 ⩽ Fr ⩽ 9; 0 ⩽ Re ⪅ 2400; 0 ⩽ β ⩽ 85°. Phenomenologically, our experimental flow observations vary from well mixed fully diffusive regimes, through buoyancy-dominated inertial exchange regimes, to laminar viscous flows, all with varying degrees of stability. We characterize the different flow regimes observed in terms of the three dimensionless groups and provide leading order approximations to the velocity of the displacement front and the macroscopic diffusion in each regime.
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buoyant miscible displacement flows at moderate viscosity ratios and low atwood numbers in near horizontal ducts
Chemical Engineering Science, 2012Co-Authors: Seyed Mohammad Taghavi, K Alba, I A FrigaardAbstract:Abstract We present results from a study of buoyant miscible displacements flows at moderate viscosity ratios in near-horizontal ducts. Low Atwood numbers are considered. Inertial effects are significant although the flow regimes are laminar. Pipe and plane channel geometries are considered using a mix of experimental, computational and analytical techniques. The main focus of the study is on the effects of the viscosity ratio between the Fluids. We show that small viscosity ratios lead to more efficient displacements, as is intuitive. In each geometry we find a mix of viscous and inertial flows, in broadly the same pattern as for the iso-viscous displacements studied extensively in Taghavi et al. (submitted for publication) . Predictive models are proposed for the viscous regime, in the case of the plane channel, and for the inertial exchange flow regime, in both geometries. We also study displacement flows with shear-thinning Fluids, over a more restrictive range of parameters. We show that with an appropriate definition of the effective viscosity the scaled front velocities fit well with the results from the Newtonian displacements, in both pipe and plane channel geometries. The main role of ratio m of Displaced Fluid viscosity to displacing viscosity is in line with our intuition. For m > 1 displacement efficiencies are reduced and the front velocities are larger. However, the main increase in front velocity is achieved for modest viscosity ratios of 3 or 4 to 1, with little increase afterwards. The reverse situation, m 1 , shows significant improvements in displacement efficiency, with front velocity V ^ f reduced down towards the imposed mean velocity V ^ 0 , as m decreases. A viscosity ratio of around 1–4 appears to achieve quite efficient displacements, and to be able to compensate for the effects of buoyancy (which in our case are always destabilising).