Crude Oil Foams: Testing and Ranking of Antifoams with the Depressurization Test

The addition of chemicals is the most widely applied solution to prevent the formation of foam or to destroy it immediately after its generation as a result of its simplicity and efficiency. Among the different chemicals that can be used as antifoams or defoamers, polydimethylsiloxane (PDMS) oils are the most common, followed by fluorosilicone oils for the most severe cases. Nonetheless, there is no clear management on the selection of these additives; therefore, it is still based on a trial-and-error basis. For this reason, we have studied the properties and effectiveness of different chemical additives by defining two parameters based on the logistic model developed for the study of the defoaming kinetics of crude oil foams formed by depressurization: the effect on the foamability or antifoamability effect (AE) and the effect on foam stability or destabilization effect (DE). Finally, we have tried to go further in the understanding of the mechanisms involved in foam breaking, looking for similitudes on the defoaming behavior in the different crude oils tested.