Study On Synthesis And Properties Of A Novel Naphthalene Replaced α-olefin Sulfonate As Anionic Surfactant For EOR

The typical surfactants used in enhanced oil recovery, such as petroleum sulfonates and heavy alkylbenzene sulfonates etc. are usually cheap and easy to obtain. However, these surfactants have complicated compositions and usually contain components not clear in chemical structure, leading to difficulty in property and quality controlling during production. On the other hand, conventional surfactants with clear chemical structure are not suitable for enhanced oil recovery, for lack of enough hydrophobicity. In this paper, we attempt to synthesis a novel anionic surfactant, naphthalene-replacedα–olefin sulfonate (NAOS), with much stronger hydrophobicity than AOS, by reacting the sulfanatedα–olefin with naphthalene based on the Berger's principle, and to examine its potential application in enhanced oil recovery.The results show that NAOS can be synthesized in the absence of catalyst by the reaction of the sulfonatedα–olefin with naphthalene. The main factors influencing the reaction include naphthalene/suffocatedα–olefin molar ratio, temperature and reaction time. By using orthogonal experimental procedure, an optimal reaction condition is found: reacting for 5 h at 150°C with naphthalene/sulfonatedα–olefin molar ratio equal to 1.2. Under this condition a yield as high as 91.27% can be obtained. By characterization with IR, UV, and Mass spectra the synthesized product was proved to have a molecular structure of naphthalene-replacedα-olefin sulfonate. NAOS shows similar saturated adsorption and molecular cross section area at saturated adsorption to AOS at air/water interface. However, NAOS displays a cmc two magnitude lower than that of AOS, or 9×10-6 mol/L, due to the connection of the naphthalene group to the hydrocarbon chain. Theγcmc seems to keep unchanged. Because the sulfonate group is connected to hydrocarbon chain instead of aromatic ring, NAOS, although with much more carbon atoms totally, shows a salinity tolerance similar to LAS, indicating that NAOS has a good tolerance to electrolytes. By formulating with other surfactants and in the presence of weak alkali such as sodium carbonate, NAOS can reduce Daqing crude oil/water interfacial tension to an order of 10-3 mN/m at 45°C and can be used as surfactant for enhanced oil recovery accompanied with weak alkali.