Synthesis,Performance Evaluation Of Temperature-resistant And Salinity-tolerant Surfactant And Its Construction Of Oil Flooding System

Aiming to the challenge to chemical agents using in high-tempareture and high-salinity reservoirs,researches were carried out about surfactant flooding system with characters of heat resistance and salinity tolerance.New kind of surfactant,aliphatic amine polyoxyethylene ether sulfonate?ACS?was designed and synthesized,which can reduce interface tension?IFT?to ultra low under Tarim reservoir conditions of temperature 110 °C,salinity 11.5×10⁴ mg/L and Ca²⁺&Mg²⁺7654 mg/L.Firstly,using aliphatic amine polyoxyethylene ethers as raw materials,six aliphatic amine polyoxyethylene ether sulfonate surfactants?ACS?were synthesised by addition reaction of alkenes through a two-step reaction : allylation and sulfonation.Optimum synthesis conditions were determined used aliphatic amine polyoxyethylene ethers?5?as raw materials,intermediate and final products were characterized as allyl ethers and sulfonates by FI-IR and ¹H-NMR.Their decomposition temperatures are among 300³75 °C,indicating that six sulfonate surfactants have better thermal stability.Among six ACS surfactants,the critical millecular concentration?cmc?of ACS-1202 and surface tension at cmc is 0.172 mmol/L and 29.96 mN/m,respectively.It shows that ACS-1202 has better surface performance.Secondly,through experiments and theory simulation methods,the influence of temperature and salt ions on the adsorption behavior of ACS surfactants in the oil/water interface was investigated.ACS surfactants show better ability of heat resistance and salt tolerance due to the strong hydration as a consequence of three hydrophilic groups of tertiaty amine,ethoxy and sulfonate in surfactant molecule.Tertiaty amine and ethoxy groups are insensitive to salt ions,and sulfo group exhibits better ability to resistant salt ions.The resistant ability of ACS surfactants to salt ion is Na⁺>Ca²⁺>Mg²⁺.Meanwhile,sulfo group has good thermal tolerance.Under high temperature,head groups are not obvious aggregation,but agglomeration degree of surfactant membrance is high because of the increasing flexibility of alkane chain.The thickness of interface layer is decreased,causing IFT values to decrease firstly then increase.The results of two methods are coincident.Finally,through systemic performance evaluation and contrast,ACS-1202 exhibited better abilities of lowering IFT to 0.0046 mN/m and thermal stability.During the aging time of 30 days,IFT values maintained 10^-3mN/m.Oil displacement system was constructed with ACS-1202 as main reagent and sulfobetaine?THSB?as assisting reagent,which can reduce IFT to ultra low under harsh Tarim reservoir conductions.Synergism was proved that the values of cmc and ?cmc of the mixed system is lower than that of single component.The oil displacement system composed by 0.2% ACS-1202 and 0.02% THSB can lower IFT to 0.0021 mN/m,and has a little bigger recovery increment of 5.20% than ACS-1202.The oil-displacement mechanism was studied through microscopic visualization experiments.