Due to the high throughput requirement of most oilfield separation systems, gravity separation of the emulsions is insufficient, particularly
if the relative gravitational difference between hydrocarbon and water is negligible — e.g., steam-assisted gravity drainage (SAG-D).
Therefore, assistance is required to achieve satisfactory throughput. To achieve optimized demulsification, natural gas needs to be removed
from the fluids to encourage quiescent coalescence of the emulsion. This is physically aided through heating of the oil and/or the emulsion
pad, which helps melt waxes and reduce the crude oil's viscosity, allowing the water droplets to settle out more quickly.
However, by far the most common treatment to help break the emulsion is the addition of formulated chemical demulsifiers. These chemical
additives are usually injected at the wellhead to achieve adequate mixing prior to the separator so that the demulsifier can reach the
target interface and function effectively. To reach the surface of the emulsified water droplets, the demulsifier blend must have the right
solubility. The chemical demulsifier is attracted to the emulsifying agent through differences in polarity. Once at the target, it
neutralizes the effect of the emulsifying agent, allowing the finely dispersed water droplets to coalesce upon contact. As the water droplets
increase in size, they tend to settle, separating the water from the oil.
The stability of an emulsion is unique to each reservoir, and may vary from well to well. As such, it is necessary to develop demulsifier
blends specifically targeted at the fluids produced. RIMPRO demulsifier products should be considered as concentrated raw materials, or
intermediates, for the preparation and/or formulation of oilfield demulsifiers and dehydrating chemicals. Field demulsifiers are usually
blends of two or more intermediates, selected on the basis of their performance in bottle tests and centrifuge tests, the methods of which
can be found in separate publications.
These tests help identify the products that produce the maximum amount of water and the cleanest oil. The samples should be examined for
fastest water drop, sludging, quality of the interface, and quality of the water. The best-performing candidates should have bottle tests
repeated using different combinations and concentrations until eventually the best performance blend is found.
