The role of asphaltenes, resins and other solids in the stabilization of water in oil emulsions and its effects on oil production in Saudi oil fields

The factors contributing to the stability of water-in-oil (w/o) emulsions is a problem of great concern and economic importance to the oil companies in the production of oil from underground reservoirs. This paper reports the results of a laboratory investigation into various factors affecting the stability of w/o emulsions in some crude oil samples obtained from well heads of different oil fields in the Eastern Province of Saudi Arabia. A pressure sampling technique was used to collect the upstream samples from well heads. The emulsion samples were collected both from problem (tight emulsions) and non-problem (loose emulsions) wells. Solids present in the produced fluids were separated by successive toluene dilution and were analyzed for their composition using various methods such as XRD, TGA, and DSC. These data indicate that these solids consist of calcite, wax, asphaltene and resins. The oily parts of the samples were separated into asphaltenes, resins and maltenes. The asphaltene fraction is found to play an important role in the stabilization of w/o emulsions. Asphaltene adsorbs on mineral and wax particles, thus contributing significantly to emulsion stability.