Study On The Synthesis And Compound Perfoemance Of Surfactants For Tertiary Oil Recovery

The most promising of tertiary recovery technologies is the surfactant flooding which belongs to chemical flooding.There are some problems in domestic oil flooding surfactants,such as the difficulties in the development of new surfactants,a single surfactant can not achieve all requirements,the chromatographic separation phenomenon caused by the large structural gap in the mixed system,the difficulty in the development of an alkali-free flooding system and the oil displacement effectiveness is restricted in the oil reservoir with the characteristics of high temperature and high salinity.In view of the above problems,based on the previous studies of our group,this paper explores the surfactant blending system of alkali-free.The anionic-nonionic surfactants and amphoteric surfactants acted as the main agent respectively in the mixed systems,the effect of different mixed-proportion,total concentration,salinity and hardness were also disscussed.The main contents and results were as follows:Fatty alcohol ethers were used as raw materials,C₁₂AEC₃ was synthesized under suitable conditions?the molar ratio of fatty alcohol polyoxyethylene ether,sodium hydroxide and sodium chloroacetate is 1.0:1.5:1.1,and reacted at 75? for 8h?.The product was analyzed by FT-IR,ESI-MS and the result showed that the product was C₁₂AEC₃,then the physical chemical properties and surface chemical properties of C₁₂AEC₃ were preliminarily studied.Based on this,the interfacial chemical properties of the mixed system after mixing C₁₂AEC₃with BS-22,BS-18,BS-16,BS-12 and 6501 were analyzed.There are three binary systems with good flooding effects,which were BS-16/C₁₂AEC₃,BS-18/C₁₂AEC₃ and 6501/C₁₂AEC₃,then explored synergy between them and studied the best formulation in alkaline-free flooding.The results show that there are different degrees of synergistic effects among the three mixed systems.In the three systems,the oil/water interfacial tension of Shengli crude oil is reduced to 10^-3 mN·m^-1 within a relatively wide concentration range with a small amount of C₁₂AEC₃ added.BS-16/C₁₂AEC₃,BS-18/C₁₂AEC₃ and 6501/C₁₂AEC₃ compound systems could be used in petroleum reservoir with salinity concentration less than 20000 mg·L^-1 and content of Ca²⁺and Mg²⁺around 500 mg·L^-1.The quaternary amination reaction was used to convert erucamide dimethyl tertiary amine to erucamide propyl betaine?EAB?,EAB was synthesized at 80? for 7h and the molar ratio of tertiary amine and sodium chloroacetate was 1.0:1.1,the reaction conversion rate reached 95.2%.The product was analyzed by FT-IR and ESI-MS and showed that the product was EAB,and the betaine content of purified product was 97.3%.The chemical properties of the surface of the EAB were preliminary studied.Based on this,the interfacial chemical properties of the mixed system after mixing EAB with 6501,OA-12,C_20²4AOS,C₁₂AEC₃,and C₁₂AEP₃ were analyzed.There are two binary systems with good flooding performance,which were 6501/EAB and C_20²4AOS/EAB,then we explored the synergy between the binary system and studied the best formulation in alkali-free flooding.The results show that the mixing of the 6501/EAB is close to the ideal mixture.There is a synergistic effect in the C_20²4AOS/EAB mixed system.Both systems can reduce the interfacial tension of Daqing crude oil to 10^-3mN·m^-1 over a wide molar ratio and concentration range.The compounding system can be used in reservoirs with contents of Ca²⁺and Mg²⁺around 200mg·L^-1 and salinities less than 12000mg·L^-1.