Fingering, viscous

If the mobility ratio is greater than 1.0, then there will be a tendency for the water to move preferentially through the reservoir, and give rise to an unfavourable displacement front which is described as viscous fingering. If the mobility ratio is less than unity, then one would expect stable displacement, as shown in Figure 8.16. The mobility ratio may be influenced by altering the fluid viscosities, and this is further discussed in Section 8.8, when enhanced oil recovery is introduced. 

The effects of flow nonuniformities, in particular, can be severe in gas systems when the ratio of bed-to-particle diameters is small in liquid systems when viscous fingering occurs as a result of large viscosity gradients in the adsorption bed when very small particles (<50 Im) are used, such as in high performance liqmd chromatography systems and in large-diameter beds. A lower bound of the axial... 

Single porosity Efficient Optimized Flexible Low cost Good for QC Viscous fingering... 

The dissolution of high molecular weight analytes increases the viscosity of the samples. Samples with a high viscosity can exhibit viscous fingering on the column top. Because this phenomenon can impair resolution, it is recommended to keep the sample concentration below certain limits. These limits are shown in Table 11.5. 

Virial coefficients (GC) 5 Viscosity detector (SEC) 452 Viscous fingering (SEC) 447 Visualization techniques (TLC) (see derivatization (TLC)] Void volume, column (LC) 371 measurement 372 Volman trap (GC) 211 Volume of a theoretical plate 49... 

Bhaskar KR, Garik P, Turner BS, Bradley JD, Bansil R, Stanley HE, et al Viscous fingering of HC1 through gastric mucin. Nature 1992 360 458-461. 

The effects of flow nonuniformities, in particular, can be severe in gas systems when the ratio of bed-to-particle diameters is small in liquid systems when viscous fingering occurs as a result of large... 

A major problem with viscous fingering is that reproducible peak shapes, albeit distorted, may be observed this may be highly misleading in interpreting SEC results. To obtain reliable results, molecular weight distributions of samples should be obtained as a function of polymer concentrations to arrive at a value in which peak distortion is not present or peak shape does... 

Danger. J.S. "Dendrites. Viscous Fingers, and the Theory of Putiem Formation."... 

Viscous fingering," 74 VOCs. See Volatile organic compounds (VOCs)... 

Viscous fingering of HC1 through gastric mucin. Nature 360, 458-461... 

Nittmann, J., Daccord, G., and Stanley, H., Fractal growth of viscous fingers A quantitative characterization of a fluid instability phenomenon, Nature, Vol. 314, 1985, pp. 141-144. 

For at least three decades, long before the recent widespread initiation of field projects, adverse mobility ratio has been recognized as a major technological problem -- perhaps "the major problem" -- of gas-flood EOR (7-9). Adverse mobility ratios produce "viscous fingering," a displacement phenomenon that has been known and studied both experimentally and theoretically for many years (9-14). This phenomenon was a principal reason for the failure of many of the liquified petroleum gas (LPG) floods of the 1950 s and early 1960 s (15). 

When the mobility ratio is greater than one, the front between the displaced and displacing fluids is unstable if the porous medium is sufficiently wide (> 10 cm) to allow the formation and propagation of viscous fingers. The lower viscosity fluid channels or "fingers" through the displaced fluid, leaving much of it uncontacted. (See... 

Figure 1 shows schematically viscous fingering, which occurs because the injection fluid is less viscous, and gravity override, which occurs because the injection fluid is less dense. Chapter 2 of this book, by Chang and Slattery, describes a linear instability analysis for gas flooding and also introduces a nonlinear treatment of the flow instabilities. 

We will focus our attention here upon miscible displacements (1-4). In a miscible displacement, there is no phase boundary between the displaced and displacing fluids, only a mixing zone in which composition is a function of position. A general review of viscous fingering is given by Homsy ( 5). ... 

IMMISCIBLE CO2/OIL. SET NO. 2. EXPERIMENT NO. 3. This experiment should be compared with experiment No. 1. The CT scans showed a sharp, nearly vertical, CO2 front without viscous fingering. Figures 14a-d. The CO2 entered the core in the upper half of the inflow face and then swept down, forming a small layover angle. A C02-free oil bank developed during the flood but was overtaken by the faster moving CO2. CO2 and oil production were simultaneous at the outflow end of the core. 

The mobility-control surfactant increased the apparent viscosity of CO2 sufficiently to prevent gravity override and viscous fingering. The bulk CO2 phase passed through the core in a piston-like manner. Oil and most of the brine were displaced from the core ahead of the bulk-phase CO2. Differential pressure measurement across the length of the core indicated an average gradient, 1.3 psi/ft, similar to that observed during the brine flood. 

In particular, the gravity-viscous force ratio and the ratio of transverse dispersion to longitudinal convection rate were made as close as possible to the prototype oil reservoir. These ratios control respectively the extent of gravity segregation and the extent of viscous fingering (for ai given unfavorable mobility ratio). 

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