Dynamic interfacial tension behavior of the novel surfactant solutions and Daqing crude oil

The added surfactant, ionized acid and unionized acid adsorbed simultaneously onto the interface, resulting in the low DIT. Introducing sodium chloride has an obvious effect on DIT behavior of crude oil and surfactant flooding systems through affecting surface-active species' absorption behavior onto interface and distribution between oil and water. With the increase of salinity, the required optimum surfactant concentrations increase. There exist obviously both synergism and antagonism between the added surfactant and inorganic salt (also between surfactant and alkaline) in lowing DIT Towards the stronger lipophilic surfactant, antagonism occupies dominant, but synergism is dominant status if lipophilicity is weak. DIT curves between alkyl methylnaphthalene sulfonate surfactant solutions and Daqing crude oil take on "V-shape". Through changing the parameters flooding systems like surfactant concentration, alkalinity and salinity, the shape of "V" curves may be changed, even DIT in. Therefore, varying parameters of flooding systems can satisfy the demand of DIT for crude oil in different oil field. For Daqing crude oil, the developed surfactants, except for Hex-MNS, exhibit good DIT behaviors. Based on the previous result, the AMNS surfactants might be a good candidate for enhanced oil recovery in different oil fields. (c) 2006 Elsevier B.V. All rights reserved.