Pipeline transportation of viscous crudes as concentrated oil-in-water emulsions

Stable concentrated oil-in-water (O/W) emulsions were prepared and their application for heavy oil pipeline transportation was investigated using very viscous Malaysian heavy crude oil. Two Malaysian heavy crude oil samples, Tapis and a blend of Tapis and Masilla, were used to produce heavy crude oil-in-water emulsions. The diverse factors affecting the properties and stability of emulsions were investigated. There was a restricted limit of 68 vol% and 72 vol% for crude oil content in the emulsions, and beyond that limit, the emulsion underwent phase inversion. The study revealed that the stability of the oil-in-water emulsion stabilized by Triton X-100 increases as the surfactant concentration increases, with a subsequent decrease in the crude oil–water interfacial tension (IFT). Increasing the oil content, the speed and duration of mixing, the salt concentration and the pH of the aqueous phase of the emulsion resulted in increased emulsion stability, while increases in the temperature of the homogenization process substantially reduced the viscosity of the prepared emulsions. Fresh water and synthetic formation water were used to study the effect of aqueous phase salinity on the stability and viscosity of the emulsion. The results showed that it was possible to form stable emulsions with synthetic formation water characterized by a low dynamic shear viscosity.

► During oil lifting, transportation and processing, emulsions and sludge are created. ► High temperature reduces the O/W emulsion stability. ► Stability of O/W emulsion increases with emulsifying concentration. ► O/W emulsions show strong unstable behavior of water within the emulsion due to the absence of an emulsifying agent. ► O/W emulsions are used for transportation of heavy crude oil through pipelines.