Crude oil emulsions

An important industrial example of W/O emulsions arises in water-in-crude-oil emulsions that form during production. These emulsions must be broken to aid transportation and refining [43]. These suspensions have been extensively studied by Sjoblom and co-workers [10, 13, 14] and Wasan and co-workers [44]. Stabilization arises from combinations of surface-active components, asphaltenes, polymers, and particles the composition depends on the source of the crude oil. Certain copolymers can mimic the emulsion stabilizing fractions of crude oil and have been studied in terms of their pressure-area behavior [45]. 

Demulsifiers for crude oil emulsions should meet the following properties ... 

The performance of demulsifiers can be predicted by the relationship between the film pressure of the demulsifier and the normalized area and the solvent properties of the demulsifier [1632]. The surfactant activity of the demulsifier is dependent on the bulk phase behavior of the chemical when dispersed in the crude oil emulsions. This behavior can be monitored by determining the demulsifier pressure-area isotherms for adsorption at the crude oil-water interface. 

A process for separating crude oil emulsions of the water-in-oil type based on certain ethylene oxide-propylene oxide block pol5miers and certain poly-glycidol ethers of phenol-formaldehyde-condensation products has been described [1026-1028]. 

Quaternary oxalkylated polycondensates can be prepared by esterification of an oxalkylated primary fatty amine with a dicarbonic acid. An organometallic titanium compound is used as a catalyst for condensation [842]. The reaction product is then oxalkylated in the presence of a carbon acid [841], These polycondensates can be used as demulsifiers for crude oil emulsions and as corrosion inhibitors in installations for the production of natural gas and crude oil they can and also be used in processing. 

Alkylpolyglycosides. Oxalkylated alkylpolyglycosides have a low toxicity and are biodegradable [172]. The amount of demulsifier to be used to break crude oil emulsions is related to the mass of the emulsion. The maximal mass is 1 to 5000 ppm, preferably 1 to 1000 ppm the temperature is preferably 40° to 80° C. 

H. Diaz-Arauzo. Phenolic resins and method for breaking crude oil emulsions. Patent US 5460750,1995. 

R. Kupfer, W. Bose, M. Hille, R. Bohm, and F. Staiss. Process for the separation of crude oil emulsions of the water-in-oil type (Verfahren zum Trennen von Erdolemulsionen vom Typ Wasser-in-Ol). Patent EP 333141, 1989. 

W. K. Stephenson and J. D. Deshazo. Method of breaking crude oil emulsions using ethylene carbonate adducts of alkylphenol-formaldehyde resins. Patent US 5205964,1993. 

Although, many other methods (e.g. electrostatic separation, heating, centrifugation, etc.) may be used to separate the oil and water phases, chemical demulsification is the most inexpensive and widely used technique to resolve crude oil emulsions. The demulsifiers are oil-soluble water-dispersible non-ionic polymeric... 

The major problem in demulsifying crude oil emulsions is the extreme sensitivity to demulsifier composition. There have been attempts (2, 3) to correlate demulsifier effectiveness with some of the physical properties governing emulsion stability. However, our understanding in this area is still limited. Consequently, demulsifier selection has been traditionally based on a trial and error method with hundreds of chemicals in the field. 

Specified concentrations of TFSA were injected into sample bottles containing 0.1 dm3 of the untreated crude oil emulsion. The sample bottles were then capped, vigorously shaken and heated to the approx>riate reservoir temperature. The volume percentage of the total water phase which separates from the oil, the clarity of... 

Pretreatment. Minimizing the degree of oil contamination in produced water starts with the crude oil emulsion treating system. It is possible to economically operate an emulsion treating system to produce a low bs w. (basic sediment and water) oil at the expense of exceptionally oily water. 

Caims, R.J.R. Grist, D.M. Neustadter, E.L. The effects of Crude Oil-Water Interfacial Properties on Water-Crude Oil Emulsion Stability in Theory and Practice of Emulsion Technology, Smith, A.L. (Ed.), Academic Press New York, 1976 pp. 135-151. 

Smith, V.H. Arnold, K.E. Crude Oil Emulsions in Petroleum Engineering Handbook, Bradley, H.B. (Ed.), Society of Petroleum... 

Figure 2. Facilities required for a heavy-crude-oil emulsion transportation...

In processing petroleum emulsions, chemical treating compounds may be added to a crude-oil emulsion to produce desirable oil quality and remove water or inorganic solids. The most common types of treating compounds are referred to as emulsion breakers. Various mechanisms are postulated as to how emulsion breakers function, but it is clear that an emulsion breaker must reach the interface of an emulsified droplet and the surrounding liquid. At that point, an emulsion breaker disrupts the interfacial tensions between oil and water and allows the droplets to coalesce and settle by gravity. 

An emulsion is a system consisting of a liquid dispersed as droplets in a second immiscible liquid, often stabilized by an emulsifying agent. In the oil field, the two basic types of emulsions are water-in-oil and oil-in-water oil-in-water emulsions are often termed reverse emulsions. More than 95% of the crude-oil emulsions formed in the oil field are of the water-in-oil type. Nonetheless, oil-in-water emulsions are receiving growing interest in pollution abatement as they are readily miscible with water. 

An innovative technique involving the preparation of a lower-viscosity unstable slurry-emulsion system by mixing water with the oil as a means of conveying crude oil has yet to be proven on a commercial scale. The technical problems and issues limiting the application of this technique (analogous to crude-oil emulsion pipelining) are to sustain the two immiscible liquids in a stable emulsion during transport and to destabilize the emulsion... 

Free-Water Knockout. By definition, free water is any water associated with the crude-oil emulsion that settles out within 5 min while the produced fluids are stationary in a settling space within a vessel. Free-water knockouts (FWKO) are simply three-phase separation vessels that separate... 

Although FWKOs are not considered to be treatment equipment per se, their discussion here is appropriate because they are used extensively in conjunction with treatment equipment. Specific applications for FWKO vary with each situation. In some cases, the amount of water removed by the FWKO may not be crucial provided the treatment facilities downstream are performing effectively. When excessive amounts of water are produced with the crude-oil emulsion, as in secondary recovery (i.e., water-flood) projects, it may be necessary to specify requirements of 20% water to ensure proper treater performance. 

Figure 8. Particle Size Distributions of Two Crude Oil Emulsions (Shell Crude 3.0 x 10 moles NaOH/gram oil, St. Lina Crude 3.0 x 10 moles NaOH/gram oil).

Recently, we have shown that sulfonated PHP can act as a demulsifier for highly stable emulsions like crud and water-in-crude oil emulsions. The mechanism of demulsification is that sulfonated PHP removes selectively surface active species in the emulsion, causing destabilization. At the same time, it also adsorbs metal ions, thus achieving two functions at the same time. As a result, these materials are called demulsifier adsorbers. In highly stable emulsions where neither electric field nor demulsifier adsorbers are effective, the combination of these two methods appears to create synergy for separation. 

Akay, G. Dogru, M. Calkan, B. Calkan, O.F. Flow induced phase inversion phenomenon in process intensification and micro-reactor technology. Process intensification in water-in-crude oil emulsion separation by simultaneous application of electric field and polymeric demulsifiers. In Microreact Technology and Process Intensification Wang, Y., Halladay, J., Eds. Oxford University Press Oxford, 2005 Chapter, 18. 

Akay, G. Noor, Z.Z. Dogru, M. Process intensification in water-in-crude oil emulsion separation... 

The chemical composition and physical properties of the different types of oil are described in Chapter 3. The oils that are used in this book to illustrate the fate, behaviour, and cleanup of oil spills are introduced. These represent the primary oil and petroleum products used and spilled. They are gasoline, diesel fuel, a light crude oil, a heavy crude oil, an intermediate fuel oil (IFO) which is made from a heavy residual oil and diesel fuel, a residual oil, sometimes called Bunker fuel, and crude oil emulsion. 

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