More Oil, Less Chemicals - pH Control In Crude Desalting

By Mettler-Toledo AG, Process Analytical, Inc.

Crude oil usually contains a considerable amount of water. This can be water injected into the well as part of the recovery process or it can be water that is naturally present in the oil reservoir. The water is actually brine and contains various dissolved mineral salts. The crude may also contain crystalline salts, sediment and corrosion products such as rust (from cargo holds). All these contaminants need to be removed before the crude is refined as they cause fouling and corrosion of downstream equipment. Inorganic salts such as magnesium chloride and calcium chloride tend to be particularly problematic as these salts are so called Lewis acids, which means that under refinery process conditions they hydrolyze and form extremely corrosive hydrochloric acid. Other contaminants may also have a direct negative impact on downstream processes, for example certain metals present in the crude poison catalysts and render them useless.