Demulsifier blends

Bottle testing, therefore, is always an essential part of the experimental work prior to pilot or field tests. Work at the Saskatchewan Research Council on characterization of several oilfield emulsions coupled with chemical characterization of commercially available demulsifiers and demulsifier blends showed that physical processes (temperature, pumping, and dispersed water size distribution) were at least as important as the chemical effects associated with demulsifier and oil chemistry in determining demulsifier effectiveness [I3-J5]. 

Statistical evaluation of demulsifier properties and performance can be useful in reducing the number of jar tests required by targeting chemically similar demulsifier blends. The data used to characterize and group the various demulsifier blends should account for some fundamental demulsifier properties. One method that has been used successfully is the chemical characterization of demulsifiers using carbon 13 nuclear magnetic resonance (C-13 NMR), although many other characteristics could be used. 

Figure 13. Carbon 13 nuclear magnetic resonance spectra of a demulsifier blend showing the spectral regions typical of poly-oxyethylene (EO), poly-ethylene (PE), poly-propylene oxide (PO), and xylene diluents (benzene derivatives, BD). The areas under the peaks are proportional to the amount of the component in the blend.

Figure 15 shows the score plot of the two principal components with four distinct clusters. These clusters represent demulsifier blends with similar chemical compositions. Figure 16 shows the demulsifier performance superimposed on the clusters of similar composition. The corre-... 

Figure 15. Two-dimensional score plot of the 198 demulsifiers characterized using C-13 NMR data. The clusters, or proximity, of demulsifier scores indicate chemically similar demulsifier blends.

A demulsifier composition that is a blend of (1) a propoxylated-ethoxylated block copolymer of a bis-hydroxyalkyl ether and (2) a propoxylated-ethoxylated block copolymer of 2-hydroxymethyl-1,3-propanediol has been described [1750,1751]. 

A blend of a polyoxyalkylene-polysiloxane copolymer and an alkoxy-lated phenol-aldehyde resin is useful as a demulsifier [1457, 1458]. 

It is very rare that a single chemical structure will produce all the lour primary actions of a demulsifier, namely. (I) strong interface attraction. (2) flocculation. (3) coalescence, and (4) solids wetting. Generally two or more structures are blended to gethcr to produce a compound which gives the necessary combination ol actions. 

Most chemical agents used for demulsification are preferentially oil-soluble blends consisting of HMW polymers. These blends commonly consist of (1) floc-culants (large, slow acting polymers) (2) coalescers (LMW polyethers) (3) wetting agents and (4) sol-vents/cosolvents. Some chemical structures of demulsifiers used for breaking crude oil emulsions have been listed by Jones et al. (42). Much work has been carried out in order to identify and understand the mechanisms behind chemical demulsification. Fiocco (43) concluded that the inter facial viscosity was kept at a low level when demulsifiers were present. Later on it was realized that the interfacial shear viscosity of crude oil emulsions does not have to be very low in order to ensure accelerated water separation (44). 

Chem. Descrip. Sodium dioctyl sulfosuccinate CAS 577-11-7 EINECS/ELINCS 209406-4 Uses Wetting agent, emulsifier, demulsifier for textile wet processing, specialty cleaners dewatering agent for flotation cones., oil spill cleanup blends vise, depressant in emulsion PVC food pkg. adhesives, paper emulsifier in mfg. of food-contact articles in resinous/polymeric food-contact coatings... 

The presence of solids further complicates the requirement for an effective demulsifier in that the agent used must ensure that the solid surface is water wet. Various surfactants are more effective at preventing rag layer formation and others are effective over wide concentration ranges (less susceptible to overtreating). Blends of demulsifiers are often employed to satisfy these sometimes conflicting process requirements. 

An Empirical Approach to Demulsifier Selection. Research into emulsion fundamentals added greatly to our understanding of the factors that determine emulsion stability and the surface-active chemicals that can be used to manipulate those factors. In spite of these advances, the requirement for blending demulsifiers in order to achieve acceptable field performance means that empirical approaches are often required for demulsifier selection. In fact, complete characterization of emulsion properties, including process residence times, temperatures, and product requirements still only provides guidance in the selection of process demulsifiers. The costs and time involved in achieving the level of characterization required for a fundamental approach can also be... 

Fiocco and coworkers demonstrated the use of two dispersant apparatuses to test demulsifiers, the WRASET , which uses the wrist-action tester or EXDET test, and the ROFLET , which uses the rolling flask or Warren Springs test [J6S], To demonstrate the test, an emulsion with Kuwait crude oil was used with the Exxon products, Breaxit OEB-9, 7877, 8150, and 8160, and the surfactant dioctyl sulfosuccinate. Effectiveness was measured by visually observing the amount of water/oil separation. A Sture blend crude was used to evaluate the same demulsifiers plus Ameroid 372101, Breaxit 4018, 711, 7125, 7128, and 7652, as well as Shell LA 1834, Alcopol 60, and a demoussifier . Ameroid was found to be the best product, followed closely by Breaxit 4018, 7111, 4018, and then LA 1834. 

Chem. Descrip. Sulfonate/resin blend Uses Demulsifier for bad tank bottoms Properties 70% act. 

Chem. Descrip. Resin/wetting agent blend Uses Demulsifier Properties 28% act. 

Uses Film-fanning mst preventive by conversion to metallic soaps lubricity agent by conversion of free add to esters emulsifier or demulsifier by conversion to amine or alkanolamine soaps conosion inhibitor by blending with other surfactants... 

Demulsifiers and corrosion inhibitors are often the cause of poor dehydration performance. Corrosion inhibitors are surfactant chemicals that often act as emulsifying agents, thus making the demulsifier work harder. In cases of conflict, it is usually easier to blend a new demulsifier or change the injection points of the chemicals than it is to replace the corrosion inhibitor. However, in some North Sea fields the opposite was true. Corrosion inhibitor replacement was the best way to deal with the incompatibility problem. 

Commercial demulsifiers are polymeric smfactants such as block copolymers of polyoxyethylene (EO) and pwlyoxypropylene (OP) (1) or alkylphenol-formaldehyde resins (2), or blends of different surface-active compounds and polyfunctionalized amines with EO/PO copolymer (3, Figure 8) (Kokal, 2005). 

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