Flooding indications

The WAG process has been used extensively in the field, particularly in supercritical CO2 injection, with considerable success (22,157,158). However, a method to further reduce the viscosity of injected gas or supercritical fluid is desired. One means of increasing the viscosity of CO2 is through the use of supercritical C02-soluble polymers and other additives (159). The use of surfactants to form low mobihty foams or supercritical CO2 dispersions within the formation has received more attention (160—162). Foam has also been used to reduce mobihty of hydrocarbon gases and nitrogen. The behavior of foam in porous media has been the subject of extensive study (4). X-ray computerized tomographic analysis of core floods indicate that addition of 500 ppm of an alcohol ethoxyglycerylsulfonate increased volumetric sweep efficiency substantially over that obtained in a WAG process (156). 

Figure 6.15 shows the difference in residual oil saturations after glycerin flood and after polymer flood. Because their viscosity and interfacial tension to oil were about the same, the further significant reduction in residual oil saturation by polymer flooding was probably caused by the polymer elasticity. Wang et al. (2000b) showed that the initially oil-wet surfaces became more water-wet after polymer flood, indicating that polymer flood can strip off more oil films from rock surfaces. 

Sharp rate of rise of pressure drop. A sharp rate of rise of pressure drop with vapor rate may be an even more sensitive flooding indicator than the magnitude of pressure drop. The flood point can be inferred from a plot of pressure drop against vapor or liquid flow rate, and is the point where the slope of the curve changes significantly (Figs. 14.3,14.4). In tray columns, the slope change can be relatively mild (curve 1 in Fig,... 

Rapid rise in entrainment. A rapid rise in entrainment is another common flooding indicator (2, 91, 367). This is often recognized as a large rise in reflux or product rate for a small or no increase in reboil. Bleeders (see below) have also been used to detect this rise in entrainment... 

The experimental evidence from the long core floods indicates that ambient pressure effects on foam behaviour need to be taken into account. Two additional pressure correlations were established (no oil present) specific to the foam system investigated ... 

Experimental effluent profiles may be fitted directly to the analytic form of Equation 7.15, provided that the solute experiences only dispersion, equilibrium linear reversible adsorption and/or excluded-volume effects. Figure 7.2 shows an analytical fit to the experimental effluent profile of a tracer flood indicating that only dispersion occurs in this case. In some experimental situations, however, the analytic form in Equation 7.15 is inadequate to describe the observed effluent profiles, and other phenomena need to be considered, as discussed in the following section. 

A computer simulation study on the impact of different parameters on the economics of polymer flooding indicated that the percentage of polymer which remains in the reservoir in immobile fluids and is not adsorbed ranges from 20 to 50 per cent of the injected volume, depending on reservoir conditions and the WOR at the economic limit of production (9). 

Estimation of the oxobasidty index, pIl, on the basis of Lux-Flood indicator of acid-base reactions is part of oxobasicity evaluation. Let us consider the following scheme ... 

The data show a midrange dry efficiency of 0.7 (70 percent). They indicate a flood F-factor value of about 3.0. Thus, the approach to flood is 2.6/3.0 = 0.87 (87 percent). The data were taken at total reflux, and thus F c = (0.481/841)0.5 = 0.024 (densities taken from Example 9). From Fig. 14-26, = 0.19, and from... 

Blockage of liquid Monitor pressure drop across vent system (e.g., effluent line due local indication, alarm or interlock) to closed valves,, Interlock valve in feed line to centrifuge results in flooding of basket and Equipment/line-up checks overflow from Remove unnecessary valves basket to solid col-. 5, lection system in base. Possibility of liquid spill. ... 

Flooding across a column section reflects itself in an increase in pressure drop and a decrease in temperature difference across the affected section. Product quality is also impaired, but it is hoped that the other indicators will allow correction of the situation before major change in product quality. When a column floods, the levels in the accumulator and bottom often change. It can occur that the accumulator fills with liquid carried over while the reboiler runs dry. 

Figure 3.17 depicts an ultra-shallow TOF SIMS depth profile of a 100-eV B-implant in Si, capped with 17.3 nm Si. The measurement was performed with 600-eV SF5-sputtering and with 02-flooding. The original wafer surface, into which the B was implanted, is indicated by the maxima of the alkali- and C-signals. Because of these contaminants, a minimum is observed in the °Si-signal. The dynamic range of the B-profile is more than 3.5 decades and the depth resolution is <0.5 nm. 

Indoors, indicative of a total flooding system outdoors requiring assessment of exposure of nearby hazards, involvement of other combustibles, wind effects and difficulty of extinguishment. 

The potential for natural disaster, based on die history and knowledge of the region and eaitli structure, should be indicated in die plan. Items such as seismic fault zones and flood plains, and potentials for hurricanes and winter storms should be noted. 

The values of a/e determined experimentally by Lobo et al. are indicated [47]. These are the values in the development of the basic relation expressed in Figure 9-21A with correction of i]) suggested by Leva [41]. These a/values were found to correlate a considerable amount of the literature data within 12%. This would mean about a 6% error in tower diameter determined at flooding conditions. 

As a comparison or alternate procedure, the pressure drop at the flooding point as indicated by the upper break in the pressure drop curve can be estimated from Table 9-33 and Figure 9-34D for rings and saddles [81]. The values in the table multiplied by the correction ratio gives the pressure drop for the liquid in question, expressed as inches of water. 

The only available test data [44] indicate that the plain flat plate (26-45% free area) has a decided detrimental effect on the allowable flooding conditions of the tower whereas the wire screen, weir-type, and fused Raschig ring designs have very little effect when using Intalox saddles for packing. 

There is not much data available on this point. Operational experience plus qualitative tests indicate that entrainment is negligible until the packing reaches the flooding condition. See discussion under distillation section. 

Figure 9-62. Flooding data for structured packings as reported by Billet [109]. Numbers following packing type indicate specific surface area in m /m. Reproduced by pennis-sion of the American Institute of Chemical Engineers, Fair, J. R. and Bravo, J. L., Chemical Engineering Progress, V. 86, No. 1 (1990) p. 19 all rights reserved. Note, Uq = vapor velocity, meters/sec.

---