表面活性剂对油溶性降黏剂降黏效果的影响及作用机制

Influence and mechanism of surfactants on viscosity reduction effect of oil-soluble viscosity depressant

以轮古稠油为原料,考察十六烷基三甲基溴化铵(CTAB)、十二烷基磺酸钠(SDS)和OP-10(OP)对自制的油溶性降黏剂马来酸酐-苯乙烯-丙烯酸十八醇酯共聚物(MSA)降黏效果的影响;通过相对黏度法和质量分数电导率法,从沥青质缔合性和稠油胶体稳定性两个方面分析表面活性剂在稠油降黏过程中的作用机制。结果表明:1%的MSA能使稠油黏度从6.720 Pa·s下降到2.810 Pa·s,同时使稠油沥青质的缔合度减小,稠油胶体稳定性增强;CTAB、SDS和OP的加入均能继续提高MSA的降黏效果,其作用效果顺序为CTAB>SDS>OP;SDS和OP能促进MSA对沥青质的解缔作用,使沥青质缔合度继续减小,而CTAB不具备促进MSA解缔沥青质的能力;CTAB、SDS和OP均能促进MSA增强稠油胶体稳定性,其作用效果顺序为CTAB>SDS>OP,这与3种表面活性剂增强MSA降黏效果的能力顺序一致;对于轮古稠油,相对于稠油沥青质的缔合性,体系胶体稳定性是影响MSA降黏效果的主要因素。

The effects of Cetyl trimethyl ammonium bromide（CTAB）, Sodium dodecyl-sulfonate（SDS） and OP-10（OP） on the viscosity reduction rate of self-manufactured oil-soluble viscosity depressant, the copolymer of maleic anhydride, styrene and octadecyl acrylate（MSA） with Lungu heavy oil as raw oil were investigated. The influencing mechanism of surfaetants was analyzed from the standpoints of asphaltene association properties and colloidal stability of heavy oil by the methods of relative viscosity and mass fraction normalized conductivity. The results indicate that 1% MSA can reduce the viscosity of heavy oil from 6. 720 Pa·s to 2. 810 Pa·s, decrease the aggregation number of asphaltene, and enhance the colloidal sta- bility of heavy oil. All of CTAB, SDS and OP can improve the viscosity reduction effect of MSA, and the influencing order is CTAB〉SDS〉OP. SDS and OP can improve the dissociation of MSA to asphaltene, make the aggregation number of asphah- ene decrease continuously, but CTAB does not have the ability to improve the dissociation of MSA to asphahene. All of CTAB, SDS and OP can improve the ability of MSA to enhance the colloidal stability of heavy oil, and the influencing order is CTAB〉SDS〉OP, which is consistent with the results of surfactants improving the viscosity reduction effect of MSA. The results show that compared with the asphahene aggregation properties, the colloidal stability of heavy oil is the primary factor affecting the viscosity reduction effect of MSA for Lungu heavy oil.