Liquid-liquid Displacement Research Articles

Thickness of residual wetting film in liquid-liquid displacement

Core-annular flow is common in nature, representing, for example, how streams of oil, surrounded by water, move in petroleum reservoirs. Oil, typically a nonwetting fluid, tends to occupy the middle (core) part of a channel, while water forms a surrounding wall-wetting film. What is the thickness of the wetting film? A classic theory has been in existence for nearly 50 years offering a solution, although in a controversial manner, for moving gas bubbles. On the other hand, an acceptable, experimentally verified theory for a body of one liquid flowing in another has not been available. Here we develop a hydrodynamic, testable theory providing an explicit relationship between the thickness of the wetting film and fluid properties for a blob of one fluid moving in another, with neither phase being gas. In its relationship to the capillary number Ca, the thickness of the film is predicted to be proportional to Ca2 at lower Ca and to level off at a constant value of ∼20% the channel radius at higher Ca. The thickness of the film is deduced to be approximately unaffected by the viscosity ratio of the fluids. We have conducted our own laboratory experiments and compiled experimental data from other studies, all of which are mutually consistent and confirm the salient features of the theory. At the same time, the classic law, originally deduced for films surrounding moving gas bubbles but often believed to hold for liquids as well, fails to explain the observations.

Generalized Buckley-Leverett problem

Analysis of the effect produced by thermal and gas treatment on oilfield reservoirs of the Bazhenov formation involves the dynamics of a porous saturated medium with a multiphase multicomponent fluid, taking into account the chemical and physicochemical transformations under thermal and gas injection. This work is a qualitative investigation into such processes based on a simplified partial model allowing analytical study. The process of hot water injection into hydrocarbon-saturated reservoirs is considered. The physical statement of the problem is the generalization of the BuckleyLeverett problem additionally taking into account mass and heat sources. The purpose is to study the mechanism of heat and mass transfer in a porous medium with allowance for chemical and physicochemical transformations. By way of example, an analytical solution of the problem is considered using a specific algebraic expression for the Buckley-Leverett function. Our research makes it possible to identify some qualitative features of the general model and to draw significant practical conclusions. The results can be applied to the investigation into a wide scope of processes of liquid-liquid displacement in a porous medium with two-phase and multicomponent fluid in the presence of heat and mass sources.

Dynamics of Liquid−Liquid Displacement

Capillary driven liquid-liquid displacement in a system with two immiscible liquids of comparable viscosity was investigated by means of optical high speed video microscopy. For the first time, the impact of substrate wettability on contact line dynamics in liquid-liquid systems was studied. On all substrates, qualitatively different dynamics, in two distinct velocity regimes, were found. Hydrodynamic models apply to the fast stage of initial spreading, while nonhydrodynamic dissipation dominates contact line motion in a final stage at low speed, where the molecular kinetic theory (MKT) successfully captured the dynamics. The MKT model parameter values showed no systematic dependence on substrate wettability. This unexpected result is interpreted in terms of local contact line pinning.

Immiscible liquid-liquid displacement in capillary tubes: viscoelastic effects

The displacement of a fluid by liquid injection occurs in some practical applications like oil recovery in porous media and cementation of drilling wells. The dimensionless numbers that govern this problem are the capillary number, Reynolds number and viscosity ratio. An overview of selected oil recovery processes shows that hydrolyzed polyacrilamide and bio-polymers, as xanthan gun, are commonly pumped into oil reservoir in order to aid oil recovery. These materials are non-Newtonian, presenting high viscoelastic effects. The fractional mass deposited on the tube wall and the shape of the interface on liquid-liquid displacement of two Newtonian materials was studied previously by Soares et al. (2005). The goal of the present work is to conduct an experimental investigation analyzing viscoelastic effects on the fractional coverage and on the shape of the interface for both: a polymer displacing a Newtonian liquid and a Newtonian liquid displacing a polymer.

Immiscible Liquid-Liquid Displacement in Capillary Tubes

We analyze the liquid-liquid displacement in capillary tubes. The goal is to determine the amount of displaced liquid that remains attached to the tube wall and the configuration of the liquid-liquid interface at different operating parameters. The study encompasses both numerical and experimental approaches. The finite element method is used to solve the governing equations and, in order to validate the predictions, visualization experiments are performed to capture images of the interface. The numerical results were obtained for the assumption of negligible inertia, and the effects of viscosity ratio and capillary number are investigated. The predictions and experimental observations are in good agreement.

Viscous Fingering During Miscible Liquid-Liquid Displacement in Porous Media

Viscous Fingering During Miscible Liquid-Liquid Displacement in Porous Media

Characterization of polyacrylonitrile ultrafiltration membranes

Various methods have been used to characterize ultrafiltration membranes, such as gas flux measurements, (field emission) scanning electron microscopy, permporometry and liquid-liquid displacement. Significant differences in the pore size distributions determined from permporometry and liquid-liquid displacement were found.

Effects of buoyancy forces on miscible liquid-liquid displacement processes in a porous medium

The effects of buoyancy forces on the displacement of one liquid by another in a consolidated porous medium have been investigated experimentally for the specific case in which the two liquids are completely miscible. In order to obtain a clear understanding of the favorable and unfavorable effects of buoyancy forces, experiments were carried out in three different flow modes, namely horizontal, vertical-downward and vertical-upward. As the effects of buoyancy forces are negligible for two-dimensional porous media in the horizontal flow mode, the results obtained in this mode were used as a reference for comparison with those obtained in the two vertical modes. The miscible system employed consisted of an aqueous glycerol solution and distilled water (dyed with methylene blue) as the displaced and displacing fluids respectively. Displacements using five different density ratios were studied, with the density ratio being varied by changing the concentration of the glycerol solution. The breakthrough time and fractional recovery of the displaced fluid were measured in each case and photographs of the unstable fingering patterns were taken for a wide range of injection flow rates. The results obtained indicate that the effects of buoyancy forces can be very significant, especially at low flow rates and/or at high density ratios. When the density of the displacing fluid is less than that of the displaced fluid (which was the case in the present work), buoyancy forces play a deleterious role in vertical-upward displacements since they tend to promote fingering and reduce breakthrough times, thereby producing low recoveries of the displaced phase. In contrast, under the same density conditions, buoyancy forces play a positive role in vertical-downward displacements since they then tend to stabilize the displacement process (i.e. reduce fingering), thereby producing increased breakthrough times and correspondingly high recoveries of the displaced phase. However, at high flow rates, the observed fingering patterns and recoveries are very similar for horizontal, vertical-downward, and vertical-upward displacements, since viscous forces are dominant under such conditions and buoyancy forces are insignificant.

Immiscible, Viscoelastic Liquid-Liquid Displacements in Permeable Media

Slow, immiscible, viscoelastic liquid-liquid displacement in a permeable medium is considered. The necessary and sufficient criteria for stability are that the displacing fluid is denser and less mobile than the displaced one. The instability criteria and critical wavelength are found to be the same as those for ordinary viscous liquid-liquid displacements in permeable media.

Effects of Buoyancy Forces on Immiscible Water/Oil Displacements in a Vertically Oriented Porous Medium

The effects of buoyancy forces on liquid-liquid displacement processes occurring in porous media are important in a variety of practical situations, in particular during the displacement of oil from partially-depleted underground reservoirs by means of aqueous solutions. Most previous studies involving the visualization of water/oil displacements in porous media have been undertaken in horizontal two-dimensional porous medium cells. The objective of the present work was to determine the effects of buoyancy forces; on the fingering pattern and oil recovery by conducting immiscible displacement experiments in two-dimensional consolidated porous medium cells aligned in the vertical plane. In order to obtain a clear understanding of the favourable and unfavourable effects of buoyancy forces, experiments were carried out in three different flow modes, namely horizontal, vertical upward, and vertical downward. As the effects of buoyancy forces are negligible for two-dimensional porous media in the horizontal flow mode, the recoveries obtained in this mode were used as a reference for comparison with those obtained in the two vertical modes. Displacements using five different density ratios were studied. The breakthrough time and percentage oil recovery were measured in each case. The effects of buoyancy forces, viscous forces, and capillary forces, as well as the injection flow rate, were also recorded. The results obtained indicate that the effects of buoyancy forces are very pronounced at low flow rates and low oil/water density ratios, and that even a slight increase in the flow rate causes the buoyancy forces to rapidly become less significant.

Porosimetric Characterization of Inorganic Membranes

Abstract This paper deals with the evaluation of pore size and pore size distribution of inorganic membranes by liquid-liquid displacement porometry. Carbon and ceramic membranes were tested with a fully automatic porometer, and different results were obtained depending on the type of membrane. Membranes were also examined with the aid of a scanning electron microscope. The results of porosimetric measurements are discussed in conjunction with those of microscopic observations.

Visualization of the effects of buoyancy on liquid-liquid displacements in vertically-aligned porous medium cells

The results of this work suggest that the use of two-dimensional porous medium cells aligned in the vertical plane affords a promising experimental technique for studying the very significant effects that buoyancy forces are capable of exerting on the stability of liquid/liquid displacement processes in porous media. The cell described here is relatively easy to use and permits a wide range of cell orientations, flow modes, injection points, and recovery points to be investigated. Detailed quantitative studies involving a wide range of fluids, flowrates, and flow modes, are currently under way and will be reported in due course.

Onset of viscous fingering for miscible liquid-liquid displacements in porous media

The displacement of one fluid by another miscible fluid in porous media is an important phenomenon that occurs in petroleum engineering, in groundwater movement, and in the chemical industry. This paper presents a recently developed stability criterion which applies to the most general miscible displacement. Under special conditions, different expressions for the onset of fingering given in the literature can be obtained from the universally applicable criterion. In particular, it is shown that the commonly used equation to predict the stable velocity ignores the effects of dispersion on viscous fingering.

Immiscible liquid-liquid displacement in thin quartz capillaries

At low rates of spontaneous displacement (υ ⩽ 5 × 10 −3 cm sec ) advancing contact angles θ A. are close to their static values. In the case of forced displacement, at flow rates 10 −2 − 10 −1 cm sec , after retreating meniscus there are formed thick nonequlibrium wetting films. Capillary counter-pressure reaches the maximal value P c = 2γ 12/r. At still higher flow rates, υ > 0.1 cm sec , coalescence of dynamic films and emulsification in meniscus zone take place. In hydrophobized capillaries, at υ ⩽ 10 −2 cm sec , usually no dynamic wetting films are formed after retreating meniscus, and θ A values are constant.

Mobility Control In Dynamic Gravity Segregation Flow Systems

Abstract Experiments were carried out in a vertical sand pack to study the effect of gravity segregation on liquid displacement by a miscible liquid, a gas and a combination of the two. The advantages of using a foaming agent during simultaneous gas-liquid injection were also investigated. A gamma-ray attenuation technique was adapted to track the shapes of the moving displacement front and monitor in-situ saturation profiles. The results show that high gas mobility and low density lead to early gas breakthrough and poor sweep efficiency. Even in miscible liquid-liquid displacements a density difference of 0.079 g/cm3 leads to gravity override or under-ride by the displacing liquid. During simultaneous gas-liquid injection the presence of gas increases the severity of the over-ride/under-ride effect and reduces the displacement efficiency of the miscible liquid. In-situ generation of foam is an effective method of controlling the mobility of the gas and improving the conformance of the displacement front. Introduction The purpose of this study was to investigate the characteristics of gravity segregating systems and the use of foaming agents to control the mobility of air and water injected simultaneously into a liquid-saturated porous medium. One of the major factors responsible for poor conformance and low recovery efficiency of several displacement processes(1) is gravity segregation caused by a density difference between displacing and displaced fluids. For example gas-driven processes such as CO2-flooding, alternating water-gas injection, steam injection and in-situ combustion are affected by varying degrees of segregated flow behavior. Several laboratory experiments and numerical studies of fluid flow in porous media have confirmed the importance of a density difference in the occurrence of segregation. Slower rates of segregation were observed in brine-liquid systems than in brine-air systems(2). With miscible liquids the length of the mixed zone was influenced by gravity segregation, and a greater reduction in displacement efficiency was observed when the mixed zone was narrow compared to the height of the experimental model(3). The presence of a broad transition zone tended to nullify the influence of a difference in density(4,5). Gravity segregation is generally thought to be time-dependent and more prevalent in thick heavy oil reservoirs(6). However, some field projects have also shown that segregation can occur instantaneously at the wellbore(7,8), and in static gas-liquid systems only a short time is required for an initially uniformly distributed gas phase to reach a fully segregated state(9). For unit mobility ratios, two miscible fluids will segregate in dynamic flow by the same amount they segregate in a static system(10). Studies in models simulating both linear and five-spot patterns show that volumetric sweep efficiency at breakthrough can be as low as 20% of those with no gravity segregation(11). This reduction in performance is more pronounced with an increase in vertical or horizontal permeability, an increase in density difference, a decrease in production or injection rates, and an increase in mobility ratios(6). Gravity override has been observed in nearly all steam-drive Projects(12). For reasons of convenience, theoretical studies often assume vertical combustion fronts, even though gravity effects are usually evident(12).

The effect of radial diffusion on the performance of a liquid-liquid displacement process

The effect of radial diffusion on the performance of a liquid-liquid displacement process is considered in fluid flow between porous parallel plates and through a porous tube, as examples of a two-zone problem in unsteady-state mass transfer. The double Laplace transformation is applied to the system equations. In obtaining the inversion of the Laplace transformed equations the first inversion (with respect to the transformed dimensionless axial distance) is performed by use of the residue method, and then the second inversion (with respect to the transformed dimensionless time) is performed by use of the numerical Laplace transform technique advanced by Bellman et al. A numerical example is shown and discussed.

Axial dispersion in fluid flow through porous plates in parallel and through a porous tube

Effects of axial diffusion on liquid-liquid displacement in fluid flow through porous plates in parallel and through a porous tube are considered as problems of two zones in unsteady state mass transfer. The solutions of the differential equations of the system in terms of the Laplace transformed variable contain an infinite number of essential singularities in a complicated form. Therefore approximate solutions are obtained by numerical inversion of the Laplace transform. Some of the numerical results are presented and discussed.

Solid-Like Films at a Moving Interface

The petroleum literature shows a sporadic but sustained interest insolid-like films adsorbed at oil-water interfaces. A number of investigatorshave described their occurrence, attempts at isolation and some properties. Recently, more attention has been focused on the possible influence of suchfilms in oil production, particularly in waterflooding. Except for the work ofReisberg and Doscher, the influence of adsorbed films on the movement of anoil-water interface near a solid boundary appears uninvestigated. Also, noattention has been given to the possible movement of the film during a liquid-liquid displacement at a solid surface. That the effect of movement of athree-phase interline requires consideration can be illustrated by thefollowing simple experiment. A large, glass bell jar 12 in. in diameter wascleaned and filled with distilled water. After testing the water surface forcontamination, a cleaned glass slide (75 x 50 x 1.5 mm) was immersed verticallyin the water along its length. The slide was held rigidly, almost entirelyimmersed, by attaching it to a mechanism which permitted its withdrawal from orimmersion into the water surface at constant velocity (about 0.1 cm/minute). Talc powder was then liberally sprinkled over the entire water surface and acardboard box was placed over the apparatus to shield the water surface fromair currents. The water interface could be viewed and photographed throughplastic windows mounted over holes in the box. At rest, the talc particles wereuniformly distributed over the water-air surface. No talc particles, however, were found on the surface of the meniscus; i.e., no particles were present onthat part of the water-air surface drawn up from the common level by thewetting of the glass slide (contact angle through water theta, theta 0). Thisexperimental situation is depicted in Fig. 1a which represents the "at rest"configuration of the particles on the water-air surface. As the glass slide wasmoved in a direction which would withdraw it from the surface, the talcparticles for the first time began to ascend the meniscus. Their ascentoccurred in a reasonably coherent front. The particles appeared to move adistance along the surface of the meniscus equal approximately in length to thedistance the glass slide was removed from the water surface. If the motion ofthe slide was arrested, the particles slid down the meniscus and returned tothe common liquid level. If the upward movement of the slide was continued orrestarted, the particles again began ascending the surface of the meniscus(Fig. 1b). Upon reaching the top of the meniscus, the particles began todeposit on the slide to which they adhered. If the direction of motion of theslide was reversed (yet never leaving the water surface) the particles at thecommon level began to move away from the meniscus. Also, particles attached tothe glass slide (from the previous deposition) upon reaching the top of themeniscus, detached and descended the meniscus. This behavior was very strikingbecause the talc particles descended the meniscus in profuse streams ratherthan in a coherent front, as in their ascent (Fig. 1c). However, not allparticles detached from the slide upon meeting the top of the meniscus. Thosewhich did not detach simply remained on the glass slide and were submerged. Asbefore, if the motion of the glass slide was arrested, the particles on themeniscus slid down and adopted the configuration shown in Fig. 1c. A completelyanalogous result was obtained when the experiment was repeated using mercuryinstead of water. In this case, the mercury surface near the glass slide wasdepressed (meniscus below the common mercury level, contact angle >90). After immersing the glass slide, particles were placed upon the mercurysurface. Nearly all the particles slid into the depression and concentratednear the glass slide. If the slide was moved upward, the particles climbed thesides of the depression. attained the common mercury level and moved away fromthe depression. If the motion was arrested, the particles again slid into thedepression. If the slide was moved downward, particles on the common leveldescended the depression. Particles in the depression became submerged, presumably still attached to the surface. If the downward motion of the slidewas stopped. the submerged particles did not reappear. Only when the slide wasmoved in the direction of withdrawal did the particles reappear. If themovement of the slide was continued, the particles again ascended thedepression and moved on the common mercury level away from the slide.

Interfacial Effects in Immiscible Liquid-Liquid Displacement in Porous Media

Abstract A study was made of the effects of wettability and interfacial tension the immiscible displacement of a liquid by another liquid for porous media. The influence of viscosity ratio was also investigated. Porous media used were polytetrafluoroethylene (TFE) cores prepared by compressing TFE powder under different pressures. It is shown that displacement of a wetting by a nonwetting liquid is always less efficient than the displacement of a nonwetting by a wetting fluid, all other things being equal. In the former case, the recovery efficiency can be increased substantially by either reducing the interfacial tension or increasing the viscosity of the displacing fluid. A qualitative discussion is given on the implications of this work to the recovery of crude oil by waterflooding. Introduction The high cost of oil exploration and new recovery schemes makes it imperative that waterflooding be conducted under conditions favoring most efficient oil recovery. To improve oil recovery by waterflooding, it is essential that the role played by interfacial forces in the entrapment of residual oil be studied and understood. Interfacial phenomena in natural rock, connate water and crude oil systems are very complicated because of the complexity of the natural liquids found in petroleum reservoirs, because of our inability to adequately describe the geometrical structure of the porous media and because of a lack of understanding of physical and chemical interactions between the liquids and surface of the pores. The problem becomes further complicated when one tries to elucidate the role of interfacial phenomena in fluid flow. Numerous studies of the displacement of oil by water under different interfacial tension or wettability conditions have been made. These studies have been performed in silica, alundum or sandstone systems using water and paraffin oil and also some surface active material to control the interfacial tension or and the contact angle. Unfortunately, the high energies of various interfaces involved favor adsorption and orientation of the surface active material at the intrafaces. Also the surface active material concentration at the interfaces exceeds that in the bulk of the liquid phases. Such surface excess may cause the surfactant distribution, the contact angle and the interfacial tension to differ from their measured static equilibrium values and makes interpretation of the displacement experiments difficult. Furthermore, as changes in also lead to changes in cos, the role played individually by one of these parameters in the displacement becomes obscured by the effect of the other. To circumvent these difficulties, a low surface energy solid and true solutions or pure liquids should be used. Use of a low surface energy solid minimizes adsorption and orientation effects at the solid-liquid interfaces. By controlling and cos through use of selected pairs of pure liquids or true solutions rather than by surfactants, the adsorption effects at liquid-liquid interfaces are eliminated. In the present study TFE cores were used as me porous media. Liquids used were water sucrose solutions, paraffin oils and benzyl, n-butyl and isobutyl alcohols. The interfacial tension was varied from 40 to 1.1 dynes/cm by suitably choosing the liquid pair. A surface above material was added to the water-oil system only in the case where interfacial tension of 0.5 dynes/ cm was desired. No precise changes of cos were attempted. However, either the displaced or the displacing liquid could be made the one which preferentially wets the TFE surface. Using sucrose solutions and blends of paraffin oils proved to be a convenient way of changing the viscosity ratio between the displaced and displacing liquids. The present investigation examines the effect of interfacial tension, wettability and viscosity ratio on the immiscible liquid-liquid displacement from porous media. SPEJ P. 217ˆ

Surface Chemical Displacement of Organic Liquids from Solid Surfaces1

Abstract : An investigation was made of the various factors operative in the displacement by organic liquid compounds of a bulk layer of any nonaqueous liquid from a solid surface. Although the solid surfaces used in the experiments were SAE 1020 steel and borosilicate glass, the results are readily applied to any solids. The nonaqueous pure liquids displaced were selected to cover the surface tension range and included n-hexadecane, ar-dibromoethylbenzene, tris8esyl phosphate, and propylene carbonate. A large number of well-defined displacing agents were investigated, of which the most efficient proved to be those where an optimum balance could be achieved between low surface tension, high equilibrium spreading pressure, and good solubility with respect to the organic substrate to be removed. Agents which were particularly effective for long-lasting or permanent displacement were certain classes of highly fluorinated organic compounds and lowmolecular-weight dimethyl silicones. Low-surface-tension polar hydrocarbons, such as n-alkanols, were effective for temporary displacement. The several mechanisms operative in liquid-liquid displacement from solid surfaces were investigated. It was shown that these results and generalizations include our earlier results on water displacement as a special (and extreme) case. (Author)