non-Newtonian Fluid Displacement Research Articles

Research on the Interfacial Instability of Non-Newtonian Fluid Displacement Using Flow Geometry

The variation of the classical viscous fingering instability is studied numerically in this work. An investigation of the viscous fingering phenomenon of immiscible displacement in the Hele–Shaw cell (HSC), where the displaced fluid is a shear-thinning fluid, was carried out numerically using the volume of fluid (VOF) method by adding a minor depth gradient or altering the geometry of the top plate in the HSC. The findings demonstrate how the presence of depth gradients can change the stability of the interface and offer a chance to regulate and adapt the fingering instability in response to the viscous fingering properties of air driving non-Newtonian fluids under various depth gradients. The relative breadth will shrink under the influence of the depth gradient, and the negative consequences of the gradient will be increasingly noticeable. Specifically, under different power-law indices, we found that with the enhancement of shear-thinning characteristics (lower power-law exponent n) in both positive and negative depth gradients, the fingers that protrude from the viscous fingers become shorter and thicker, resulting in higher displacement efficiency. Additionally, several modifications were performed to the upper plate’s design, and the findings revealed that the shape had no effect on the viscous fingering and only had an impact on the longitudinal amplitude. Based on the aforementioned traits, we may alter the HSC’s form or depth gradient to provide high-quality and effective work.

Annular displacement in a highly inclined irregular wellbore: Experimental and three-dimensional numerical simulations

Primary cementing of well casings is the operation where drilling fluid is displaced from the annulus between the casing and the drilled rock formation and replaced by a cement slurry. The annulus to be cemented is normally narrow and eccentric, and the formation wall may exhibit irregular geometric features such as local enlargements or washouts, originating from the drilling process and varying geological properties. Eccentricity and the presence of wellbore irregularities can lead to residual, non-displaced drilling fluid or mixing of the cement slurry with other wellbore fluids, causing contamination and failure to hydraulically isolate the annulus outside the casing. We study non-Newtonian fluid displacement in an irregular annulus experimentally and numerically for concentric and eccentric configurations of the inner pipe, and for horizontal and slanted orientations of the annulus. An overgauge section simulates a washed out zone in the wellbore. Eccentricity promotes fluid flow in the wide sector of the annulus, leading to an axial elongation of the interface between the two fluids. Depending on eccentricity and inclination, residual non-displaced fluid remains in different parts of the hole enlargement, while inclination from the horizontal is found to improve the fluid displacement in the enlarged section. The experiments and simulations agree well for the tests where the annulus is slanted, with simulations replicating displacement trends and arrival times measured in experiments. The quantitative difference between experiment and simulation is larger for the horizontal and concentric annulus tests. We discuss modelling assumptions and experiment uncertainties that can explain the observed differences.

Shear-thinning or shear-thickening fluid for better EOR? — A direct pore-scale study

Non-Newtonian fluids are widely applied in Enhanced Oil Recovery (EOR) techniques, and the good performances have been ascribed to the shear-thinning or shear-thickening characteristics of them. In this paper, we aim at discovering the roles of these rheological properties in non-Newtonian fluid displacement from the pore scale. A recently developed lattice Boltzmann model (LBM) for multiphase viscoplastic fluid flow [Xie et al. J Non-Newton Fluid, 2016.234: 118–128] is used. Displacements in both homogeneous and heterogeneous porous media are considered. For homogeneous cases, the performances of shear-thinning and shear-thickening fluids are almost the same when compared in favorable displacement regime; while the performance of shear-thinning fluid is poorer than that of shear-thickening fluid in unfavorable displacement regime. For heterogeneous cases, we demonstrate that the shear-thinning property does not contribute too much to the diversion effect, which clarifies the debate of understandings. Our pore-scale modeling results also indicate the significance of low viscosity ratio for diversion and EOR, which can stabilize the displacing front despite of the increased viscous resistance.

Thermally assisted restart of gelled pipelines: A weakly compressible numerical study

In the present study, the applicability of wall heating for facilitating the restart process of gelled pipelines by the injection of a secondary fresh fluid is evaluated using computational fluid dynamics (CFD). The secondary fluid is assumed to be injected with a constant pressure into the pipeline and at the same time the pipe wall is considered to be electrically heated by a uniform heat flux. To simulate this non-isothermal and non-Newtonian fluid displacement flow prompted by pressure wave propagation along the pipeline, the volume of fluid (VOF) method is employed and the set of governing equations are descritized using finite volume method. It is shown that the restart flow of gelled pipelines in the presence of wall heating consists of two stages: the relatively fast removal of the gelled fluid located in the vicinity of the pipe axis (breakthrough) and a gradual removal of wax-oil gel from the pipe wall (drainage). The effect of wall heating is most evident in the initial breakthrough stage where up to 20% reduction in the breakthrough time is achieved in this study with a moderate heat flux. Generally, uniform heating of pipe wall reduces the apparent viscosity of gelled fluid during restart and subsequently wall heating increases the intensity of restart flow.

Immiscible Displacement of Non-Newtonian Fluids in Communicating Stratified Reservoirs

Summary The displacement of non-Newtonian power-law fluids in communicating stratified reservoirs with a log-normal permeability distribution is studied. Equations are derived for fractional oil recovery, water cut, injectivity ratio, and pseudorelative permeability functions, and the performance is compared with that for Newtonian fluids. Constant-injection-rate and constant-total-pressure-drop cases are studied. The effects of the following factors on performance are investigated: the flow-behavior indices, the apparent mobility ratio, the Dykstra-Parsons variation coefficient, and the flow rate. It was found that fractional oil recovery increases for nw>no and decreases for nw<no, as compared with Newtonian fluids. For the same ratio of nw/no, oil recovery increases as the apparent mobility ratio decreases. The effect of reservoir heterogeneity in decreasing oil recovery is more apparent for the case of nw>no. Increasing the total injection rate increases the recovery for nw>no, and the opposite is true for nw<no. It also was found that the fractional oil recovery for the displacement at constant total pressure drop is lower than that for the displacement at constant injection rate, with the effect being more significant when nw<no.

Miscible displacement of non-Newtonian fluids in a vertical tube.

The influence of rheology on the miscible displacement of a viscous fluid by a less viscous, Newtonian one in a vertical tube is studied experimentally as a function of the flow velocity. For Newtonian displaced fluids the transient residual film thickness hri is nearly 38% of the tube radius at large viscosity ratios between the two fluids in agreement with experimental and numerical results from the literature. For shear-thinning fluids with a zero yield stress (mostly xanthan-water solutions), hri decreases down to 28-30% of the radius for the most concentrated solutions. For fluids with a non-zero yield stress, hri further decreases down to 24-25% of the radius. The orders of magnitude of these values can be obtained through numerical simulations (commercial code) for the various types of fluids. Instabilities of the film at its boundary develop downstream and lead to a reduction of the final thickness of the film at longer times: this reduction is larger for lower viscosity ratios and larger velocities.

Gas-assisted non-newtonian fluid displacement in circular tubes and noncircular channels

The motion of long bubbles into Newtonian and non-Newtonian fluids confined in horizontal circular tubes, rectangular channels, and square cross-sectional channels has been studied both theoretically and experimentally. Of particular interest is the determination of residual liquid film thickness on the walls. Isothermal experiments have been conducted to measure the displacement of the gas–liquid interface as a function of the applied pressure differential. The velocity of the interface and residual liquid film thickness have been determined for both Newtonian and non-Newtonian (shear thinning and viscoelastic) fluids. These experimental results are in good agreement with similar experimental studies conducted by other investigators. The experimental results indicate that the liquid film thickness of constant viscosity viscoelastic fluids (Boger fluids) deposited on the tube wall is thicker than that of comparable Newtonian fluids. A simple mathematical analysis was developed using a power-law model. The mathematical model successfully captures the gas–liquid dynamics for Newtonian and non-Newtonian fluid displacement in a tube and rectangular channel. The prediction of the liquid fraction deposited on the walls is in qualitative agreement with the experimental observations of previous investigators (Chem. Eng. Sci. 24 (1969) 471; A.I.Ch.E. 16 (1970) 925; Chem. Eng. Sci. 30 (1975) 379). The model gives similar results to a numerical solution (Polm. Eng. Sci. 35 (1995) 877) in which a constitutive equation containing a yield stress is used to model the non-Newtonian behavior. The model is used to determine the location and velocity of the advancing bubble front for the case of a power-law fluid. The results indicate that the gas–liquid interface advances more rapidly with decreasing values of the power-law index above a certain value of dimensionless time ( t/ t b ≈0.75).

A numerical method for simulating non-Newtonian fluid flow and displacement in porous media

Flow and displacement of non-Newtonian fluids in porous media occurs in many subsurface systems, related to underground natural resource recovery and storage projects, as well as environmental remediation schemes. A thorough understanding of non-Newtonian fluid flow through porous media is of fundamental importance in these engineering applications. Considerable progress has been made in our understanding of single-phase porous flow behavior of non-Newtonian fluids through many quantitative and experimental studies over the past few decades. However, very little research can be found in the literature regarding multi-phase non-Newtonian fluid flow or numerical modeling approaches for such analyses. For non-Newtonian fluid flow through porous media, the governing equations become nonlinear, even under single-phase flow conditions, because effective viscosity for the non-Newtonian fluid is a highly nonlinear function of the shear rate, or the pore velocity. The solution for such problems can in general only be obtained by numerical methods. We have developed a three-dimensional, fully implicit, integral finite difference simulator for single- and multi-phase flow of non-Newtonian fluids in porous/fractured media. The methodology, architecture and numerical scheme of the model are based on a general multi-phase, multi-component fluid and heat flow simulator — TOUGH2. Several rheological models for power-law and Bingham non-Newtonian fluids have been incorporated into the model. In addition, the model predictions on single- and multi-phase flow of the power-law and Bingham fluids have been verified against the analytical solutions available for these problems, and in all the cases the numerical simulations are in good agreement with the analytical solutions. In this presentation, we will discuss the numerical scheme used in the treatment of non-Newtonian properties, and several benchmark problems for model verification. In an effort to demonstrate the three-dimensional modeling capability of the model, a three-dimensional, two-phase flow example is also presented to examine the model results using laboratory and simulation results existing for the three-dimensional problem with Newtonian fluid flow.

Non-Newtonian effects on immiscible viscous fingering in a radial Hele-Shaw cell.

The displacement of a high-viscosity non-Newtonian fluid by a low-viscosity Newtonian fluid in a Hele-Shaw cell is capable of producing ramified viscous-fingering patterns exhibiting fractal characteristics. Recently, it was established that interfacial tension has little influence on the formation of these fractal patterns. However, the precise mechanism behind their formation is not as yet fully understood. In this paper, we consider the immiscible displacement of a non-Newtonian fluid in a radial Hele-Shaw cell, and present a detailed analysis of the flow, thus exposing features which until now have not been reported. In particular, we find an effective length compression for the formation of viscous-fingering patterns and accelerated growth rates, which upon consideration of recent experimental results, are consistent with the formation of fractal viscous-fingering patterns.

Self-similar solutions for displacement of non-Newtonian fluids through porous media : Zhongxiang Chen; Ciqun Liu Transport Porous MediaV6, N1, Feb 1991, P13–33

Self-similar solutions for displacement of non-Newtonian fluids through porous media : Zhongxiang Chen; Ciqun Liu Transport Porous MediaV6, N1, Feb 1991, P13–33

Self-similar solutions for displacement of non-Newtonian fluids through porous media

This paper presents a class of self-similar solutions describing piston-like displacement (single-phase flow is included as a special case) of one slightly compressible non-Newtonian, power-law, dilatant fluid by another through a homogeneous, isotropic porous medium. These solutions can be used to evaluate the validity and accuracy of existing approximate solutions, such as the assumption of constant flow rate at each radial distance that Ikoku and Ramey use to linearize the partial differential equation for the flow of non-Newtonian, power-law fluid through a porous medium.

Two-phase displacement of non-newtonian fluid

This paper considers the problem of non-Newtonian oil displacement by water in porous media, adopting the linear permeation law with initial pressure gradient. For one-dimensional flow, the basic equation of non-Newtonian oil displacement by water in sandstone reservoirs and fractured reservirs is derived and numerical solutions are obtained. The results are compared with the corresponding ones for Newtonian oil displacement to show the essential characteristics of non-Newtonian oil displacement by water.

Non-newtonian fluid displacement in an irregular annulus of axial symmetry

We describe the formulation and numerical solution of the problem of the transient displacement of one non-Newtonian fluid by another in an axially symmetric annulus. The numerical integration makes novel use of a method of characteristics to represent convective terms and an implicit backwards difference technique for other terms in the differential equations. Examples are presented showing the temporal evaluation of vortices and instabilities predicted by this integration in such displacement processes.

Laminar Displacement of Non-Newtonian Fluids in Parallel Plate and Narrow Gap Annular Geometries

Abstract Based on certain maximum gradient approximations similar to those used in lubrication theory, the miscible displacement of one non-Newtonian fluid by another is analyzed. The fluids are assumed to be of the power-law type and the displacement occurs in a parallel-plate system under conditions where dispesion effects associated with molecular diffusion and convection are negligible. The results provide predictions of displacement efficiency in provide predictions of displacement efficiency in terms of certain characteristic groups, including the density ratio of the phases, an effective viscosity ratio, a flow rate group, and the power-law slope parameters. The results should represent first-order parameters. The results should represent first-order approximations to slow flow displacements occurring in many well completion operations. Introduction The displacement of one fluid with another has been a subject of keen interest to the oil industry for many years. Although numerous studies have been undertaken on the mechanics of miscible and immiscible displacement and the associated flow instabilities and dispersion phenomena, there is still a wide range of practical problems that cannot be treated within these previous theoretical and experimental studies. This is particularly true with regard to problems involving rheologically complex, or non-Newtonian fluids. Such fluids are encountered in many facets of petroleum production, and the displacement of (or by) these fluids is crucial to current drilling and well completion practices. Such displacement problems are continually encountered in cementing operations, where one Non-Newtonian fluid is displaced with another. Although various laminar and turbulent flow techniques have evolved over the years, the basic fundamentals underlying these displacement practices go well beyond the current status of displacement theory and experimentation. Under normal circumstances these accepted practices generally lead to satisfactory cementing operations, even though it is doubtful that optimal or near-optimal displacements are ever achieved. However, in more abnormal and demanding operations these practices are often inadequate. In order to achieve optimum results, the basic flow phenomena involved in non-Newtonian displacement must be carefully understood and methods must be developed to predict displacement characteristics in terms of the rheological, kinematic, and geometric conditions involved. Unfortunately, the technology related to non-Newtonian displacement is quite limited. Most of the work to date has been concerned with the specific aspects of displacing a given drilling fluid with another (or with a given cement mixture) for a limited range of flow conditions. Only recently have the effects of rheology, density differences, flow rates, and eccentricity been considered in any quantitative detail. Specifically, Graham has presented a calculation technique for predicting the total volume of cement required to predicting the total volume of cement required to displace completely a drilling mud from an eccentric annulus under conditions of plug-flow displacement. Eccentricity is accounted for by dividing the annulus into segments and treating each segment individually. Unfortunately, displacements under plug-flow conditions are seldom realized in practice and, hence, such calculations represent only crude approximations. In a more recent study, Clark and Carters have presented experimental data on mud displacement efficiency under conditions simulating wellbore environment at 8,000 ft. These investigators indicate that higher displacement efficiencies are obtained under turbulent flow conditions. However, these results were obtained using many displacement-zone volumes of the displacing phase. In practice, because of economic considerations, only a few displacement-zone volumes of the displacing phase can be used. It is still not clear whether turbulent displacement is to be preferred in these latter situations. SPEJ P. 169