Exploration • Drilling • Field Services
For more than 50 years, Clariant Oil Services’ demulsifier technology has successfully separated the world’s oil fom water.
Separation of oil and water using environmentally-responsible demulsifier molecules
Jonathan J Wylde provides an overview of how demulsifier-based chemistries and the development of formulated products are key to competency within an organisation.
T
he formation and stability of emulsions in the oilfield are known to be affected by a number of factors: temperature, pH, heavy fraction in crude oils, solids and droplet size.
Temperature affects the viscosity of the oil,
as well as the properties of the produced water, interfacial films and emulsifier solubility in the crude oil and water. Likewise, temperature causes the energy of a fluid to rise, thereby increasing the number of droplet collisions and coagulation. Changing pH levels influences the ionisation in
the interfacial films of organic acids and bases and asphaltenes and solids. Heavy fraction in crude oil also affects emulsion formation and stability, as naturally-occurring emulsifying agents are found in higher boiling point, polar fractions. Fine solid particles can stabilise a crude oil emulsion by
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diffusing to the oil-water interface, where a film forms and hinders the coalescence of droplets. And Stoke’s Law, which describes the settling of particles in an ideal situation, helps explain that an emulsion that has a smaller average droplet size is generally more stable. When treating emulsions, the addition of chemicals is most common. Demulsifiers are surface active compounds that migrate to the oil-water interface and rupture or weaken the rigid film, thereby enhancing coalescence of water droplets. A demulsifier molecule can operate by one or more of several mechanisms:
● Preferential adsorption onto the oil-water interface and displacement of pre-existing stabilising emulsifying agents, thus removing the steric barrier.
● Spreading of the demulsifier can then occur
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