Indian Institute of Technology,Dhanbad, India
Title: Interfacial properties and adsorption characteristics of a family of synthesized zwitterionic surfactants: Implications for enhanced oil recovery
The current global energy demand is highly dependent on the extraction of natural resources that remains trapped within existing oil reservoirs. Initially, the crude oil is recovered by primary and secondary techniques. However, nearly two-thirds of the original oil in place (OOIP) still remains within the rock pores. Enhanced oil recovery (EOR) encompass a variety of mechanisms to achieve greater oil recovery by the incorporation of various techniques. One of these methods involve the injection of chemical slugs that are injected into the reservoir to effectively displace residual oil. Surfactant design is a potential area of interest in this method. Surfactants lower IFT by adsorbing onto the crude oil-aqueous interface and improve the oil displacement efficiency in chemical EOR processes.
In the present study a family of carboxybetaine based surfactants with hydrophobic tail length of 12, 14, 16 and 18 carbons were synthesized for their application in chemical EOR. The synthesis of surfactants was done by quaternizing tertiary amines of different carbon chain lengths by sodium chloroacetate. The synthesized surfactants were characterized by FTIR and 1H NMR spectroscopy and their solubility in water was tested by Krafft temperature analysis and salt tolerance test. To check for the applicability of surfactants in chemical EOR, their IFT reduction tendency, phase behavior and wettability alteration effectiveness were evaluated. Finally, sand pack experiments were conducted to test the recovery of trapped oil by injection of surfactant slug along with alkali and polymer.
IFT between oil and surfactant solution was also found to reduce with increase in carbon chain length and ultralow IFT was achieved by the synergetic effect of alkali and C16DmCB surfactant. The larger hydrophobic tail length was found to improve the oil-water interface activity. C16DmCB surfactant was found to form stable three phase microemulsion which is beneficial for its applicability in EOR. The surfactants were also found effective in altering the wettability of oil-wet quartz sample to preferentially water-wet with very lesser loss of surfactants. More than 30% additional oil recovery was achieved by the synergetic effect of alkali-surfactant-polymer in flooding experiments. The results show that the synthesized zwitterionic surfactants are having good potential for their use in chemical EOR.