Chemical demulsifier

The emulsion must be separated by the addition of chemical demulsifiers before the crude oil can be accepted for transportation. The quality criteria for a delivered crude oil are the residual salt content and the water content. For the oil to have a pipeline quality, it is necessary to reduce the water content to less than approximately 1.0%. 

R. Varadaraj, D. W. Savage, and C. H. Brons. Chemical demulsifier for desalting heavy crude. Patent US 6168702, 2001. 

Alkoxylated phenol formaldehyde resins are a well-known class of demulsifier, and the emulsion coalescence data in Table III confirm that Thin Film Spreading Agents, which belong to this class, can also function as chemical demulsifiers. When water in... 

Table III. Thin Film Spreading Agents Are a Well-Known Class of Chemical Demulsifier...

Electrostatic crude desalting systems are used in Kuwait. The system employs chemical demulsifiers, neat and an electrostatic field to dehydrate the crude. 

Film Drainage and Demulsifier Adsorption. To enhance the coagulation process, a common practice is to use chemical demulsifiers that are believed to... 

The more common emulsion formed in the petroleum industry is the water-in-oil type. The sensitivity of electrokinetic sonic analysis to coagulation-coalescence processes in water-in-oil media is of great importance. It allows for rapid selection and optimization of different chemical demulsifiers. In addition, as a research tool, it supports the development of a fundamental understanding of chemical treatment of water-in-oil emulsions. 

Chemical Methods. The most common method of emulsion resolution in both oil-field and refinery applications is a combination of heat and application of chemicals designed to eliminate or neutralize the effects of emulsifying agents. Addition of suitable chemicals with demulsifying properties specific to the crude oil to be treated will generally provide quick, cost-effective, and flexible resolution of emulsions. Success of chemical demulsifying methods is dependent upon the following ... 

Agitation. The effectiveness of any demulsifier added to a treatment system is directly dependent upon its making optimum contact with the emulsion. Therefore, the emulsion must be sufficiently agitated after the chemical demulsifier has been added. Increased mild agitation, such as in flow lines and in settling tanks, is beneficial in promoting coalescence. Re-... 

Fill a 0.5-mL syringe past the 0.5-mL mark with the desired chemical demulsifier. 

The remaining chapters address the converse, and to many, more familiar, situation in which undesirable emulsions must be broken. This treatment progresses from a focus on commercial chemical demulsifiers that may be effective to pilot- and large-scale demulsification practice. A common theme in these chapters is the use of the fundamental concepts in combination with actual commercial and pilot-scale process experiences. Overall, the book shows how to approach making desirable petroleum emulsions, transporting and handling them, and breaking them when they become undesirable. ... 

The following review presents the chemical demulsifi-cation of W/O emulsions by first introducing crudes and bitumens in terms of the diagenetic diversity and chemistries of their components. Based on the premise that a full appreciation of demulsification must be preceded by an understanding of the basics of the field and laboratory emulsions, we have reviewed demulsifica-tion and some of the characteristics of light crude, heavy oil, and bitumen emulsions researched globally. Thus, in this work the composition and behavior of the natural emulsifiers present in the crudes and some factors responsible for emulsification in the field and laboratory are addressed first. 

Wasan and coworkers (63,65,174) extended techniques for studying film rheology of the foam lamella to studies of crude-oil emulsion lamella. Using a capillary balance technique and light interferometry, the film thinning of foams was studied with and without chemical demulsifiers, with solvent properties changed, etc. (182). They confirmed that there were two contributions to emulsion stability - a struc-tiual component that originates from the nature of the bulk phase, and an adsorbed-layer contribution to film stability (170). This will be covered in another chapter in this series. 

In some situations demulsifiers have been used to inhibit emulsification (97). Demulsifiers used as inhibitors (1) in emulsification was considered in the prevention of chocolate mousse formation for oil spills (1, 268, 269). This topic has received considerable attention as increased environmental concerns demanded clean up of oil spills. Consequently, technology and chemical demulsifiers have been developed to address sea spills. However, discussion of this... 

Researchers first used the bottle tests preliminarily to select effective potential chemical demulsifiers, then would carry out further investigative studies on mechanisms for understanding demulsification phenomena for the crude at hand. 

Staiss et al. (288) have summarized the developments in chemical demulsifiers and their effeetive dosages used until 1991. They indieated then that the most recent developments in poly(ester amines) at very low dosages were most efficacious for crude oils (Table 4). Table 5 extends this development to eneompass some of the demulsifiers used by research groups globally to date. Table 5 summarizes some of the chosen ehemistries or produets used in published studies on demulsifieation of a variety of erude W/0 emulsions world wide. Aerosol OT is still used today in formulations and is one of the few demulsifiers approved by the Norwegian environmental authorities (284). Aerosol OT still appears to be sueeessful in demulsify-ing eonventional crude emulsions. However, it easily partitions into the water phase and eannot be available for a long time. 

In the first stages of cmde oil production, after crude is extracted or drilled, the fluids are under high pressures and temperatures. It is essential to recognize that flie first-stage treatment involves the removal of excess of free water and gas. If there are high salt concentrations in the water, a fresh-water wash is conducted. This wash is flien followed by addition of demulsifiers and defoamers. The chemical demulsifiers assist in the dropout of flic major amounts of water. Fiuther dehydration is achieved by use of hydrotreaters or electrostatic coalescers. This latter cannot tolerate greater than 6% water or solids. 

A wide range of chemical demulsifiers are available in order to effect this separation [89-93]. Selecting the best demulsifier however, is complicated by the wide range of factors that can affect demulsifier performance, including oil type, the presence and wettability of solids, oil viscosity, and the size distribution of the dispersed water phase. 

Jones, T.J., Neustadter, E.L., and Whittingham, K.P., Water-in-crude oil emulsion stability and emulsion destabilization by chemical demulsifiers, J. Can. Petrol. Technol, 17, 100-108, 1978. 

It has been shown that a study of crude oil/water interfacial rheology can be used to investigate crude oil emulsion stability and rationalize the effect of chemical demulsifiers. Both kinetic factors relevant to droplet coagulation and the mechanical resistance to coalescence which gives rise to permanent emulsion stability can be studied and defined by these techniques. The effects of crude oil typ e, temperature and aqueous phase changes can be followed and used to pinpoint emulsion problems that may arise in a practical situation. 

Chemical demulsification is commonly used to separate water from heavy oils in order to produce a fluid suitable for pipelining (typically less than 0.5% solids and water). A wide range of chemical demulsifiers are available in order to effect this separation. In order to develop the fundamental understanding necessary to optimize demulsifier selection for a particular emulsion, it should be sufficient, in principle, to obtain a complete chemical and physical characterization of both the emulsion to be separated and the demulsifier to be used. 

An extensive variety of chemical demulsifiers are available to enhance resolution of the water-in-od emulsion that is produced at the wellhead These demulsifiers are simply surfactants that are used to counteract the effect of surfactants naturally present in the wellhead or process emulsions, and which stabilize the water in the oil phase. In the petroleum industry, emulsions of oU in water are known as reverse emulsions. Demulsifiers are also used to destabilize these oil-in-water emulsions. The wide variety of oU types and produced water chemistries in petroleum industry emulsions necessitates an even wider variety of chemical demulsifiers. In addition, production and processing variables require demulsification chemicals tailored to particular process needs. 

Chemical demulsifiers are a class of surfactants that serve to neutralize the stabilizing effect of naturally occurring surfactants in oil emulsions. A good deal of research into the mechanisms of emulsion stability has allowed demulsifier technology to keep pace with the increasingly difficult process emulsions now being encountered. Enhanced oil recov-... 

MacConnachie, C.A. Mikula, R.J. Classification of Chemical Demulsifiers with PC A Analysis of C NMR Data and Water Dropout Performance Data , CANMET, Western Research Centre, Division Report WRC 92-60(CF), August 1992. 

Chemicals (demulsifiers) are normally used to reduce the interfacial tension. Chemical effectiveness is enhanced by mixing, time, and temperature. Adequate mixing and sufficient time are required to obtain intimate contact of the chemical with the dispersed phase. A certain minimum temperature is required to ensure the chemical accomplishes its function. Both viscosity reduction and effectiveness of chemical are dependent on the attainment of a certain minimum temperature. It may well be that the increase in chemical effectiveness is a result of the decrease in viscosity of the oil phase. 

Emulsions can be resolved or broken thermally and/or chemically. When we chemically resolve an emulsion, we use a demulsifier or emulsion breaker. These two names are used interchangeably and describe the same chemical. Chemical demulsifiers sold under various trade names, such as Tretolite, Visco, Breaxit, etc., are highly useful in resolving emulsions. Demulsifiers act to neutralize the effect of emulsifying agents. Typically, they are surface-active agents and thus their excessive use can decrease the surface tension of water droplets and actually create more stable emulsions. In addition, demulsifiers for water-in-oil emulsions tend to promote oil-in-water emulsions therefore, excessive chemical use may cause water treating problems. 

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