Molecular modeling and experimental testing on the comparative performance of macrocyclic and linear zwitterionic surfactants for the emulsified heavy oil recovery

Abstract One of the major problems in heavy oil recovery in Mexican carbonate reservoirs is related to the formation of highly stable and viscous water-in-oil emulsions, which impacts on decreasing in hydrocarbon production. This fact is derived from the presence of high amounts of asphaltenes in the oil, as well as from the high concentrations of divalent ions in the formation water. In order to develop a technological solution for this problem, in this work a theoretical/experimental methodology is presented, which allows the development of new surfactants with multifunctional capabilities, such as changes in rock wettability, interfacial tension and emulsion breaking up. The molecular modeling is used to study emulsions formation, as well as the demulsifying capability of two kinds of surfactants: branched geminal zwitterionic liquids and new zwitterionic macrocyclic oxo-aza-crown ethers. Spontaneous-imbibition studies were carried out in order to determine the capacity of these surfactants to increase the oil recovery factor. Both theoretical and experimental parts show that the new macrocyclic surfactants presented a better performance than the branched germinal zwitterionic surfactants, therefore, they constitute a potential technological solution to increase oil recovery factor in the mentioned reservoirs. Their emulsion breaking up capacity, allows to extract oil from the porous media and avoids formation of new emulsions in the extraction process.