Synthesis And Properties Of The Zwitterionic Gemini Surfactants Used In Enhanced Oil Recovery

In the 21 st century,chemical flooding is the main method for improving oil recovery in high water reservoirs due to the most reservoirs are mixed wet and oily wet,and their uneven distribution,water floods are often very inefficient in fractured oil reservoirs.Surfactant flooding in chemical flooding is a reasonable continuation of water flooding,it is not influenced by the rate of water content and is a more effective method for tapping the remaining oil and residual oil in the oilfield development process.Yan Chang Oilfield Ping 188 well area in the Xingzi Chuan oil production plant has the characteristics of high reservoir temperature and high salinity,and even a low API(crude oil density)proportion,which have all increased the difficulties of oil recovery.Two series of double quaternary ammonium salts zwitterionic gemini surfactants YLZ-0~YLZ-4 and YLZ-5~YLZ-9 have been designed and synthesized for the Ping 188 well area.The products were characterized by elemental analysis,infrared tests,nuclear magnetic resonance,mass spectrometry,and melting point tests.The physicochemical properties of the two series of surfactants YLZ-0~YLZ-4 and YLZ-5~YLZ-9 were tested,including solubility,surface tension,contact angle,interfacial tension under distilled water conditions and interfacial tension for the Ping 188 well area injection conditions.Comparing the test results of zwitterionic gemini surfactants YLZ-0~YLZ-4 and YLZ-5~YLZ-9,and the impact of alkaline enhancement of YLZ-5~YLZ-9 on the properties was observed.The CMC concentration of the surfactant YLZ-3 is 0.0178%;its effect of changing the wettability of the rock surface is the best,the contact angle is reduced from 94° to 15°;With the high salinity of Ping188 well area injected water,the interfacial tension value is 0.0053 m N/m at a concentration of 0.1%(wt%).After screening,the final concentration of 0.1% YLZ-3 was determined and tested for salt tolerance,divalent cations tolerance,emulsification,static adsorption and flooding experiment.Finally,the YLZ-3 and various types of surfactants were used in the compound experiment.The interfacial tension of the two component composite surfactant flooding solution ?YLZ-3-Na OH? was tested,which can be as low as 10-4 m N/m.They can improve the oil displacement efficiency by 10.9% based on the water flooding recovery rate of 47.8%.