Caustic spontaneous emulsification

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... 

The caustic method as a means of improved waterflooding for enhanced oil recovery is a complex process. Johnson has outlined four recovery mechanisms (6). Presumably, besides the ultralow tension mode, there are other requirements to ensure efficient and stable recovery of an oil in a given reservoir. To name a few spontaneous emulsification, entrainment, entrappment, wettability reversal in both directions, etc. In order to maintain a particular set of pro-... 

Spontaneous Emulsification and the Effect of Interfacial Fluid Properties on Coalescence and Emulsion Stability in Caustic Flooding... 

In this paper we report first the spontaneous emulsification mechanisms in the petroleum sulfonate and caustic systems. This is followed by the kinetics of coalescence in alkaline systems for both the Thums Long Beach (heavy) crude oil and the Huntington Beach (less viscous) crude oil. Measurements of interfacial viscosity, interfacial tension, interfacial charge and micellar aggregate distributions are presented. Interrelationships between these properties and coalescence rates have been established. 

Spontaneous Emulsification Mechanisms in Sulfonate and Caustic Systems... 

In the caustic system the mechanisms of spontaneous emulsification lead to the formation of both an oil-in-water and a water-in-oil emulsion. A representative photomicrograph has been included in Figure 2. 

Therefore, the mechanism of spontaneous emulsification in the caustic system is interfacial turbulence. The mechanisms for the sulfonate system are diffusion and stranding. 

Figure 2. Spontaneous emulsification in Long Beach crude oil-caustic system (a) initiation of fingering action and formation of water in oil droplets (h) termination of fingering action and formation of water in oil droplets (c) threads of oil droplets (d) formation of very thin strings and appearance of oil droplets in aqueous phase and (e) appearance of buds of oil at the oil-aqueous interface...

For the caustic systems used for recovering heavy oils it has been observed that the formation of stable emulsions by spontaneous emulsification is desirable (10, 11). The stable emulsions formed during caustic flooding tend to lower injected water mobility, viscous fingering, and water channeling while improving the sweep efficiency of the injected fluids. The produced fluids from this recovery technique are emulsions and must be demulsi-fied. 

The objective of the experiments presented here is to investigate effects of sodium hydroxide and sodium chloride on emulsion stability, and to establish the dynamics of spontaneous emulsification in a caustic system. 

The mechanisms of a spontaneous emulsification in petroleum sulfonate and caustic systems have been described. 

DT Wasan, SM Shah, M Chan, K Sampath, R Shah. Spontaneous emulsification and the effect of inter facial fluid properties on coalescence and emulsion stability in caustic flooding. In RT Johansen, RL Berg, eds. Chemistry of Oil Recovery. ACS Symposium Series 91, Washington, DC American Chemical Society, 1979, p 115. 

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