Water-in-crude oil emulsions are formed during petroleum production and asphaltenes play an important role in their stabilization. Demulsifiers are added to destabilize such emulsions,however the demulsification mechanism is not completely known. In this paper, the performances of commercial poly(ethylene oxide-b-propylene oxide) demulsifiers were studied using synthetic water-in-oil emulsions and model-systems (asphaltenes in organic solvent). No change in the asphaltene aggregate size induced by the demulsifier was observed. The demulsification performance decreased as the asphaltene aggregate size increased, so it can be suggested that the demulsification mechanism is correlated to the voids between the aggregates adsorbed on the water droplets surface.

Petroleum companies have enhanced the offshore exploration, where the fields are located under deep water. In such cases, the low temperature of the water leads to the cooling of the oil and provok...

Asphaltene precipitation/deposition is considered a problem of formation damage, which can reduce the oil recovery factor. In addition, asphaltenes can be deposited in pipelines and surface installations, causing serious complications in guaranteeing runoff, decreasing the production of oil wells. The precipitation of asphaltenes can be minimized by reducing the oil production flowrate or by using chemical inhibitors. Analyzing the stability and precipitation trend of asphaltenes in petroleum is vital for the guarantee of flow. For this purpose, several experimental and numerical methods have been proposed. Once the risk of precipitation is established, strategies can be formulated for the prevention and diagnosis of deposition problems in production or production training. The tests can be performed with dead oil, available in the wellhead, and help in understanding the behavior of the asphaltenes. This review aims to present (i) the problem related to the precipitation of asphaltenes; (ii) thermodynamic models of asphaltene precipitation; and (iii) asphaltene inhibition, control, and removal techniques using nanoparticles.