Foaming steam

In the Chaser SD1000 and SD1020 foams (steam-foam flooding additives manufactured by Chevron Oil Co.) with crude oil, the effect of oil represents intermediate cases because the emulsified oil has both destabilizing (at low oil contents) and stabilizing effects as discussed in following sections. 

Foam Flooding Processes If the injection of the surfactant solution is followed by gas injection, it can form in-situ foam, which can improve oil recovery. Several aspects of foam flooding such as mechanism of foam flow in a porous medium, microscopic behavior of foam, bubble size, CO2 foam, steam foam and oil recovery have been discussed in the literature.Several aspects of the foam flooding process are schematically presented in Figure 7. 

Although it is hard to draw a sharp distinction, emulsions and foams are somewhat different from systems normally referred to as colloidal. Thus, whereas ordinary cream is an oil-in-water emulsion, the very fine aqueous suspension of oil droplets that results from the condensation of oily steam is essentially colloidal and is called an oil hydrosol. In this case the oil occupies only a small fraction of the volume of the system, and the particles of oil are small enough that their natural sedimentation rate is so slow that even small thermal convection currents suffice to keep them suspended for a cream, on the other hand, as also is the case for foams, the inner phase constitutes a sizable fraction of the total volume, and the system consists of a network of interfaces that are prevented from collapsing or coalescing by virtue of adsorbed films or electrical repulsions. 

Prepare a mixture of 30 ml, of aniline, 8 g. of o-chloro-benzoic acid, 8 g. of anhydrous potassium carbonate and 0 4 g. of copper oxide in a 500 ml. round-bottomed flask fitted with an air-condenser, and then boil the mixture under reflux for 1 5 hours the mixture tends to foam during the earlier part of the heating owing to the evolution of carbon dioxide, and hence the large flask is used. When the heating has been completed, fit the flask with a steam-distillation head, and stcam-distil the crude product until all the excess of aniline has been removed. The residual solution now contains the potassium. V-phenylanthrani-late add ca. 2 g. of animal charcoal to this solution, boil for about 5 minutes, and filter hot. Add dilute hydrochloric acid (1 1 by volume) to the filtrate until no further precipitation occurs, and then cool in ice-water with stirring. Filter otT the. V-phcnylanthranilic acid at the pump, wash with water, drain and dry. Yield, 9-9 5 g. I he acid may be recrystallised from aqueous ethanol, or methylated spirit, with addition of charcoal if necessary, and is obtained as colourless crystals, m.p. 185-186°. 

The Kleber-Colombes rigid PVC foam (253,254) is produced by compression mol ding vinyl plastisol to react and gel the compound, followed by steam expansion. The process involves mixing, mol ding, and expansion. The formulation consists of PVC, isocyanate, vinyl monomers such as styrene, anhydrides such as maleic anhydride, polymerization initiators, FC-11, and nucleators. The ingredients are mixed in a Wemer-Pfleiderer or a Baker Perkins... 

An airspace heater ejects steam into the airspace above the product and into the foam, maintaining a temperature at least 5°C above the minimum hoi ding temperature of 63°C. The time—temperature exposure is recorded on a chart which must be kept for proof of treatment. If the Hd is opened, and the milk temperature falls below 63°C, the exposure is intermpted causing the pasteurization cycle to restart. 

Nonstabilized foams are referred to as froths froth-bonded fabrics are similar in properties to some saturation-bonded nonwovens. Typical foams used as nonwoven binder solutions have a consistency similar to shaving cream. AppHcation methods include knife-edge layering onto a horizontal web surface followed by vacuum penetration, and saturation and penetration of a vertical web surface using a horizontal-nip pad. Drying and curing is carried out in ovens, dmm dryers, or steam cans. 

Defoamers. Foam is a common problem in papermaking systems (27). It is caused by surface-active agents which are present in the pulp slurry or in the chemical additives. In addition, partially hydrophobic soHd materials can function as foam stabilizers. Foam can exist as surface foam or as a combination of surface foam and entrained air bubbles. Surface foam usually can be removed by water or steam showers and causes few problems. Entrained air bubbles, however, can slow drainage of the stock and hence reduce machine speed. Another serious effect is the formation of translucent circular spots in the finished sheet caused by permanently entrained air. 

The focus of more recent work has been the use of relatively low concentrations of additives in other oil recovery processes. Of particular interest is the use of surfactants (qv) as CO2 (4) and steam mobiUty control agents (foam). Combinations of older EOR processes such as surfactant-enhanced alkaline flooding and alkaline—surfactant—polymer flooding show promise of improved cost effectiveness. 

High temperature steam cools and eventually condenses as it propagates through the oil reservoir. To maintain foam strength as the steam cools, a noncondensible gas, usually nitrogen or methane, is often added to the injectant composition (196). Methods of calculating the optimum amount of noncondensible gas to use are available (197). 

Steam-foaming agents that efficiently mobilize heavy cmde oil by heat transfer can reduce the residual oil saturation. This can increase foam stabihty and improve the diversion of subsequently injected steam into oil saturated zones thereby increasing oil recovery (204). 

Thermal stabihty of the foaming agent in the presence of high temperature steam is essential. Alkylaromatic sulfonates possess superior chemical stabihty at elevated temperatures (205,206). However, alpha-olefin sulfonates have sufficient chemical stabihty to justify their use at steam temperatures characteristic of most U.S. steamflood operations. Decomposition is a desulfonation process which is first order in both surfactant and acid concentrations (206). Because acid is generated in the decomposition, the process is autocatalytic. However, reservoir rock has a substantial buffering effect. 

As the water evaporates into steam and passes on to the superheater, soHd matter can concentrate in a boHer s steam dmm, particularly on the water s surface, and cause foaming and unwanted moisture carryover from the steam dmm. It is therefore necessary either continuously or intermittently to blow down the steam dmm. Blowdown refers to the controHed removal of surface water and entrained contaminants through an internal skimmer line in the steam dmm. FHtration and coagulation of raw makeup feedwater may also be used to remove coarse suspended soHds, particularly organic matter. 

Thermally stable foam additives, such as alkylaryl sulfonates and C -C g alpha-olefin sulfonates, are being used in EOR steam flooding for heavy od production. The foam is used to increase reservoir sweep efficiency (178,179). Foaming agents are under evaluation in chemical CO2 EOR flooding to reduce CO2 channeling and thus increase sweep efficiency (180). 

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