高温高盐条件下纳米颗粒强化酚醛冻胶

Strengthening Phenolic Gel by Nano-SiO2 Under High Temperature and High Salinity Conditions

以丙烯酰胺与(2-丙烯酰胺-2-甲基)丙基磺酸(AM-AMPS 25)为成胶剂、水溶性酚醛树脂(WSPR)作交联剂为高温高盐油藏(130℃,41.529 g/L)研制成胶时间适宜、热稳定性好且成本低的冻胶堵剂。实验发现,尽管AM-AMPS是耐温耐盐聚合物,但其与WSPR交联形成的冻胶在高温高盐下稳定性依旧较差,冻胶老化30 d后脱水收缩严重,脱水率大于95%。而额外加入1%纳米二氧化硅(Nano-SiO_(2))的冻胶的热稳定性得到极大的改善,老化30 d后的脱水率不到1%。于是开展了纳米颗粒对冻胶成胶性能的影响及强化机理进行了研究。对加入纳米颗粒前后的聚合物溶液进行动态光散射、冷冻扫描电镜分析(Cryo-SEM)和黏度变化分析,并对加入纳米颗粒前后的冻胶进行Cryo-SEM分析。结果发现,纳米颗粒可提高聚合物溶液在高温下的黏度保留率、减小聚合物链的水动力半径、降低聚合物分子链之间纠缠的非均质性,使溶液中的聚合物分布更加均质,因而形成的冻胶网状结构也更加均质,进而提高冻胶在高温高盐下的热稳定性和持水能力。

Acrylamide and 2-acrylamido-2-methylpropanesulfonic acid(AM-AMPS 25)and water-soluble phenolic resin(WSPR)were used to develop a gel plugging agent with appropriate gelation time,long-term thermal stability,and low cost for high-temperature and high-salt reservoirs(130℃,41.529 g/L).Although AM-AMPS is a temperature and salt-resistant polymer,after crosslinking with WSPR,the thermal stability of the formed gel is far from meeting the requirements.The gel undergoes terrible syneresis when aged for 30 d and their dehydration rate is over 95%.Whereas the same gel with additional 1%nanoparticles exhibits much better thermal stability,shows no syneresis and their dehydration rate is less than 1%.Therefore,the effect of nanoparticles on the gelation properties of the gel and their stability-enhancing mechanism were investigated.Dynamic light scattering(DLS),Cryo-SEM and viscosity change analyses were applied to polymer solutions before and after the addition of nanoparticles,as well as Cryo-SEM analysis was applied before and after the addition of nanoparticles.The results reveal that nanoparticles could improve the viscosity retention of polymer solutions,decrease the hydrodynamic radius of polymer chains,and reduce the heterogeneity of entanglement between polymer molecular chains,resulting in a more homogeneous distribution of polymers in solution and therefore a more uniform mesh structure of gel is formed,thus the thermal stability and water holding capacity of gels at high temperature and high salinity are improved.