Emulsification with caustic

Emulsification with caustic is possible with oils that have a fairly high total acid number (TAN). Below about 1.5 mg KOH/gm oil, the oils either will not emulsify or will form water-in-oil emulsions. The rate of emulsification with caustic is much faster than emulsification with surfactant mixtures, which is a characteristic property for emulsions generated via the agent-in-oil procedure (1 ). 

Oils obtained from the Kern River field also emulsify readily with caustic at ambient temperatures however, heating to 43°C causes the emulsification to be more rapid. Water and sediment constitute 50% of the produced crude oil. Treated oil (generator feed) is also available in the field which contains only 2% water and, consequently, a higher TAN (total acid number) than the produced crude oil (see Table II). The treated Kern River oil forms an extremely stable 75% oil-in-water emulsion at an optimal 0.50% NaOH concentration. 

TABLE I. Emulsification of Wilmington Crude Oil with Caustic... 

The emulsification properties of the crude oil must be determined. Some crude oils can be emulsified with surfactant mixtures, others with caustic. Some crudes, such as Hasley Canyon (Table III), are difficult to emulsify. Experiments can be performed to determine if in situ emulsification is feasible, or if an emulsion must be injected. If in situ emulsification is feasible, loss of chemicals to reservoir rock is a problem to be addressed. If in situ emulsification is employed in conjunction with steam, it must be determined if chemicals are most effective when injected with the flowing steam or when chemical/steam injections are alternated. Relative permeabilities of the injected fluids should be determined. All of this information is needed to calculate the economics of scale-up to a specific field situation. 

In situ formation of oil-in-water emulsions adds the requirement that the emulsification proceed spontaneously or at least with very little energy input due to mixing. Most such systems are associated with the agent-in-oil procedure, and spontaneous emulsification to oil-in-water emulsions sometimes occurs when aqueous caustic is mixed with petroleum oils containing naphthenic acids. Some researchers propose that mass transfer of the naturally occurring surfactants across the interface is the mechanism that causes this phenomena... 

For the sulfonate system the rate of emulsification was relatively slow and yielded an unstable emulsion. The emulsification process with the caustic system was much faster and produced quite stable emulsions. 

For the short-mix process, the oil temperature is raised to 80—90°C (175—195°F) before the addition of the caustic soda. A break between the neutral oil and soapstock takes place immediately, reducing the losses due to emulsification. The contact time between the caustic and oil is reduced to a 30-sec maximum, which helps to reduce the saponification losses. Because it is standard in Europe to degum solvent-extracted oils and to condition the oils with phosphoric acid before refining, the excess caustic treatment can be eliminated or reduced substantially. The oil is finally washed with demineralized water to help remove the traces of soap remaining in the oil and dried with processes similar to the systems used for the long-mix caustic refining process. 

Recovery of acidic oils with alkaline agents by an emulsification and coalescence mechanism Calcium hydroxide [Ca(0H)2] was used to verify the emulsification and coalescence concept since, as suggested by the theoretical and experimental evidence of an earlier section, the carboxylic salts of divalent ions form unstable emulsions of water-in-oil. The emulsification and coalescence concept was quantitatively verified by secondary and tertiary flooding of partially oil-saturated sandpacks. A tertiary chemical flood with Ca(0H)2 (pH = 12) recovered 44 percent of the waterflood residual oil from a 3.5-darcy Ottawa sandpack the oil had an acid number of 2 and a viscosity of 1.5 cp. A secondary caustic flood with Ca(0H)2 (pH = 12.32) recovered 82.3 percent of the original oil in place from a 0.25-darcy Ottawa sandpack the oil phase in this secondary flood had the same physical and chemical properties as the oil phase used in the tertiary mode flood. It should be noted that the microscopic mobilization efficiencies of these... 

Uses Defoamer for paper reclaiming and caustic treatment readily emulsif able in water with good flash knockdown and staying power Foamkill DP [Crucible]... 

Uses Wetter, detergent with good oil and wax emulsification textile aux. caustic stable... 

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