Demulsifier is a chemical used to break emulsions that is, to separate the two phases. The type of demulsifier selected depends on the type of emulsion, either oil-in-water or water-in-oil.
Demulsification is used for the separation of water from crude oil. As crude oil is produced from a reservoir it tends to become mixed with either natural formation water or mixed formation and injection water. It is critical for refining process operations that the crude oil is efficiently and quickly separated from the water to allow oil to be exported and clean water to be discharged within consent, thus maximizing crude oil value and minimizing operating costs.
The severity of the emulsion formed and thus the ease at which it can be broken is dependent on:
- Physical and chemical properties of the crude oil
- Production temperature
- Distance between reservoir and topsides
- Degree of agitation experienced between reservoir and separator, turbulent flow presence of solids (sand, clay, bacteria, scale, asphaltenes, corrosion product, napthenates) and / or natural surfactants which act to stabilise the emulsion
CRUDE OIL DESALTING
Crude oil often contains water, inorganic salts, suspended solids, and water-soluble trace metals. As a first step in the refining process, to reduce corrosion, plugging, and fouling of equipment and to prevent poisoning the catalysts in processing units, these contaminants must be removed by desalting (dehydration).
One typical method of crude-oil desalting is by chemical separation using hot water as the extraction agent. In chemical desalting, water and demulsifiers are added to the crude, heated so that salts and other impurities dissolve into the water or attach to the water, and then held in a tank where they settle out.
Demulsifier selection is best performed on live crude oil thus the selection process must be performed in the field and is generally performed using the BOTTLE TEST METHOD.
Using this method numerous base chemicals can be tested on fresh emulsions and at the exact operating conditions thus a product can be formulated which is specific to the field and the emulsion. As field conditions change over its lifetime it is essential to optimize demulsifier performance on a regular basis.
DEMULSIFIER APPLICATION AREA
Factors like the nature of the emulsion and the surface equipment determine the injection point of demulsifiers. The demulsifiers can be injected downhole, in the manifold or pipelines and by batch in storage tanks. The first two are most commonly used.
The AQUACON SERIES is FILTRA’s range of Demulsifiers and can be designed to suit specific crudes. Demulsifier selection by FILTRA is normally carried out in the field by our highly experienced bottle testing engineers. A wide selection of demulsifier chemistries are screened individually and in the form of blends. FILTRA will screen more environmentally viable demulsifier bases as and when possible.