| The trimeric zwitterionics foaming agents with different hydrophobic chain length(C10,C12 and C14)were synthesized to carry out project of preventing the gas channeling utilizing foam for certain oil field with high temperature(90?100 ?)and high salinity(11×104 mg/L)in this paper.The characterization by IR,1H NMR and HRMS for trimeric zwitterionics foaming agent with C12 and its intermediate showed these foaming agents were synthesized successfully and the synthesis process of trimeric zwitterionics foaming agent with C12 was optimized by orthogonal experiment.Their properties were compared with that of dimeric zwitterionics foaming agents and monomeric zwitterionics foaming agents with similar structure to trimer which had been prepared in our laboratory early.The thermal stability,Krafft temperature,isoelectric point,surface activity,solubilization performance,foam performance,resistance to heat and salt and the simulation of anti-channeling utilizing foam of these foaming agents were studied.The preparation conditions of temperature,reaction time,medium and alkali(type and equivalent)were optimized by the orthogonal experiment,and its results showed the optimal conditions were temperature of 30 ?,reaction time of 15h,medium of DMSO,potassium hydroxide with the equivalent of 3 times in the process of preparing the glycidyl ether intermediate by Williamson-etherification.N-ethyldodecan-1-amine intermediate was conducted in the same way and its result revealed the optimal conditions were molar ratio of raw materials of 1:4.0(corresponding amide:reducing agent),temperature is 60 ?,reaction time of 40h.The thermal stability of the synthesized C12ZTFA was evaluated by thermogravimetric analysis.The results indicate that the initial temperature of thermal decomposition of C12ZTFA was 241 ? and the thermal stability met completely the needs of certain oilfield(90?100 0C).In terms of its molecular structure,C10ZTFA and C,4ZTFA,its homologues,can also meet the needs of this oil field.The Krafft temperatures of nine kinds of oligomeric foaming agents was investigated by conductivity method.It turned out that their Krafft temperatures were all lower than 0 ?,which showed their good solubility in water.Also,the isoelectric points of C12ZTFA,C12ZBFA and C12ZSFA were measured,their results showed that the isoelectric point of C12ZTFA,C12ZBFA and C12ZSFA were pI= 7.3,7,6 and 8.1,respectively,and the pI decreased slightly with the increase of the degree of oligomerization of foaming agent.The surface activities of nine kinds of oligomeric foaming agents were evaluated by surface tension method at 25 ?.It turned out that CMC value decreased with increasing length of hydrophobic chain and degree of oligomerization and the influence degree of increasing oligomerization degree was greater than that of increasing length of hydrophobic chain.The CMC of C12ZTFA with the best surface activity was 2.60×10-5 mol/L;although C14ZTFA was abnormal due to phenomenon of "the Premiceller",its CMC was 3.10×10-5 mol/L and its ?cmc decreased from 34.84 mN·m-1 to 26.12 mN·m-1 which exhibited still high surface activity.The internal reasons of their good surface activities were studied from the view of thermodynamics,and the results showed that the Gibbs free energy change of adsorption(|?Gads|)and the standard Gibbs free energy change of micellization(?Gm?|)increased both with increasing the length of hydrophobic chain(except C14ZTFA).The study on solubilization effect of nine kinds of oligomeric foaming agent C10ZSFA,C12ZSFA,C14ZSFA,C10ZBFA,C12ZBFA,C14ZBFA,C10ZTFA,C12ZTFA,C14ZTFA for phenanthrene,polycyclic aromatic hydrocarbon,indicated that their molar solubilization rate(MSR)were 0.054,0.065,0.077,0.150,0.178,0.205,0.290,0.353,0.397,respectively,and they increased with increasing the length of hydrophobic chain and oligomerization degree.The foam properties of nine kinds of oligomeric foaming agent with different concentrations and deionized water as solvent were evaluated at 25 ?.The results showed that the initial foam volume and half-life increased both with the increase of length of hydrophobic chain and oligomerization degree,but C14ZTFA was abnormal due to "the Premiceller".The initial foam volume of C]2ZTFA with the best foam performance was 850mL and its half-life was 383 s.The foam properties of nine kinds of oligomeric foaming agent with concentration of 0.4wt%and simulated formation water as solvent were evaluated at different temperatures.The results showed that initial foam volume and half-life of C12ZTFA remained the largest,reaching 634 mL and 300 s,respectively,when the temperature reached 95 ?,which exhibited the good resistance to heat and salt.C12ZTFA,with the best foam property and resistance to heat and salt,was compared with traditional foaming agent,including SDS,DHSB and DTAB,to perform dynamic indoor simulation experiment preventing the gas channeling utilizing foam.The results indicated that the resistance factor of C12ZTFA is far greater than that of the traditional foaming agent and C12ZTFA can reach the maximum resistance factor(Rf= 106.26)with the less injection rate(PV=5.26).So,C12ZTFA was compounded with SDS to further study the anti-channeling performance.It turned out that the anti-channeling performance of the compounded system with mass ratio of 1:4(SDS:C12ZTFA)was more excellent than C12ZTFA used alone and the extreme point of compounded system was PV= 5.12 and Rf= 136.16,which showed there was a synergistic effect between SDS and C12ZTFA. |
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