Development Of Viscous Fingering Research Articles

Effect of polygonal surfaces on development of viscous fingering in lifting plate Hele-Shaw cell

Effect of polygonal surfaces on development of viscous fingering in lifting plate Hele-Shaw cell

Nanotechnology for improved CO2 utilization in CCS: Laboratory study of CO2-foam flow and silica nanoparticle retention in porous media

Underground CO2 storage may reduce anthropogenic CO2 emissions, but suffer from detrimental flow instabilities mainly from development of viscous fingers and density segregation that arise at larger scales. Suggested approaches to mitigate reduction in CO2 utilization include mobility control, conformance modifications and CO2 thickeners, where CO2 foams have been shown as one of the most promising techniques. We present laboratory results that study foam generation and flow by adding hydrophilic silica nanoparticles during co-injection with liquid CO2 in sandstone core plugs to reduce CO2 mobility. Nanoparticle retention characteristics in the porous media is essential to CO2-foam flow strategies: high degree of retention may, in addition to reducing foamability, be detrimental to fluid injectivity if particle accumulation reduce the formation fluid flow capacity near the injection well. Retention was 401μg/g, in the lower range of reported literature values for aqueous surfactants, suggesting that nanoparticles to a large degree remain at the CO2-brine interface to stabilize foam when flowing through the porous medium. Elution, recovery of nanoparticles from the pore space by re-mobilization, was 79μg/g. Hence, 20% of retained nanoparticles were re-mobilized, and will contribute positively in a field application to increase foam stability further from the injection well. An apparent foam viscosity hysteresis related to the average gas saturation was observed when drainage-like (increasing gas fractions) and imbibition-like (decreasing gas fractions) injection strategies were compared. Nanoparticle-stabilized foam was also compared with surfactant-stabilized foam and the following main differences were observed: 1) maximum surfactant-stabilized foam apparent viscosities occurred at fg=0.9, compared with nanoparticle-stabilized foam with fg=0.7 (drainage-like) and fg=0.35 (imbibition-like); 2) without the presence of oil surfactant-stabilized foam have a higher (three orders of magnitude) apparent viscosity compared with nanoparticle-stabilized foam; 3) shear-thinning behavior was observed with surfactant-stabilized foam, whereas close to Newtonian behavior was observed with nanoparticle-stabilized foam; 4) no hysteresis was observed with surfactant-stabilized foams, whereas a clear hysteresis was observed with nanoparticle-stabilized foam.

Viscosity-stratified flow in a Hele–Shaw cell

A hierarchy of mathematical models describing viscosity-stratified flow in a Hele-Shaw cell is constructed. Numerical modelling of jet flow and development of viscous fingers with the influence of inertia and friction is carried out. One-dimensional multi-layer flows are studied. In the framework of three-layer flow the interpretation of the Saffman–Taylor instability is given. A kinematic-wave model of viscous fingering taking into account friction between the fluid layers is proposed. Comparison with calculations on the basis of two-dimensional equations shows that this model allows to determine the propagation velocity of the viscous fingers.

The interaction between viscous fingering and wrinkling in elastic-walled Hele-Shaw cells

The development of viscous fingers in circular Hele-Shaw cells is a classical and widely studied fluid mechanical problem. The introduction of wall elasticity (via the replacement of one of the bounding plates by an elastic membrane) can weaken or even suppress the fingering instability, but it also makes the system susceptible to additional solid-mechanical instabilities. We show that in elastic-walled Hele-Shaw cells that are bounded by sufficiently thin elastic sheets the (fluid-based) viscous fingering instability can arise concurrently with a (solid-based) wrinkling instability. We study the interaction between these distinct instabilities, using a theoretical model that couples the depth-averaged lubrication equations for the fluid flow to the Föppl-von Kármán equations, which describe the deformation of the thin elastic sheet. We employ a linear stability analysis to determine the growth rate of non-axisymmetric perturbations to the axisymmetrically expanding bubble, and perform direct numerical simulations to study the nonlinear interactions between the instabilities. We show that the system's behaviour may be characterised by a non-dimensional parameter that indicates the strength of the fluid-structure interaction. For small [large] values of this parameter, the system's behaviour is dominated by viscous fingering [wrinkling], with strong interactions between the two instabilities arising in an intermediate regime.

Development of viscous fingering between mafic and felsic magmas: evidence from the Terra Nova Intrusive Complex (Antarctica)

A wide range of types of contact morphology among mafic and felsic magmas are observed in outcrops on Vegetation Island (Terra Nova Intrusive Complex, Antarctica). Image analysis and fractal geometry techniques were applied for in-depth study of the mafic/felsic interface, with the aim of studying the origin of the varied morphologies. In particular, the length (IPN) and fractal dimension (Dbox) of interfaces were measured. Results indicate that there is a close exponential dependence of IPN on Dbox.

An Experimental Evaluation Of Viscosity Grading For Controlling Fingering In Miscible Displacements

Abstract Displacement of oil by miscible flooding processes is adversely affected by the hydrodynamic instability at the flood from whenever the viscosity ratio is unfavourable. Instabilities cause viscous fingers to grow and make the displacement process inefficientand uneconomical. Therefore, it is necessary to develop ways of reducing or eliminating the detrimental effects of viscous instabilities to make miscible flooding processes economically viable under adverse viscosity ratio conditions. Grading the viscosity of the displacing fluids appears to be an effective technique for controlling viscous instabilities. This paper presents an experimental evaluation of the efficacy of graded-viscosity solvent banks for improving the performance of solvent flooding under very adverse viscosity ratios. A scaled physical model with transparent top surface was developed for visual examination of viscous fingers during solvent floods. Base case displacement experiments were carried out to quantify the effects of viscosity ratio and flood velocity on the development of viscous fingers and the resulting displacement efficiency. The displacement experiments were then repeated with graded-viscosity solvent slugs to determine the effectiveness of such viscosity grading. Two different methods of designing graded-viscosity banks (the Claridge and the Coskuner- Bentsen methods) were examined. Results show that the extent of viscous fingering present and the resulting displacement efficiency, in the base case displacements, varied significantly with viscosity ratio and flood velocity. The use of graded-viscosity banks always reduced, and often, totally eliminated the viscous fingering. In this study, the viscous target oil was used as an additive for increasing the solvent viscosity. For field application of the graded-viscosity bank process, less expensive additives for increasing the viscosity of the solvent will be needed. Until such additives become available or the procedure can be improved upon, the use of graded-viscosity banks in miscible solvent flood appears to be uneconomical. Introduction Miscible flooding has received considerable attention in recent years because of its inherent potential to achieve a higher recovery fficiency. A 1989 survey by Thomas et al.(1) suggests that miscible flooding was the most popular method with operators in [he United States during 1980–1981, However, because of the high material and operational costs the process has become less attractive at the current uncertain oil prices. Although the miscible displacement process is not considered an obvious choice for heavy oils, it may have some potential in thin heavy-oil reservoirs where thermal methods are not suitable because of excessive heat losses to the underlying and overlying strata. However, in the case of miscible floods, high viscosity ratios between the oil and solvent often result in viscous instabilities at the front, and lead to a lower recovery efficiency. Therefore, it is important to minimize the extent and effects of viscous instabilities. Fingers in a miscible flood tend to generate a transition zone at the interface due to mass transfer. The transition zone, whose omposition exhibits continuous gradation in viscosity due to blending, arrests fingering of displacing fluid to an extent(J).