井筒条件下疏水纳米SiO_(2)对水合物形成的影响

Effect of hydrophobic nano-SiO_(2) on hydrate formation in wellbore

为研究钻井液中纳米颗粒的负面影响,利用井筒水合物动态形成模拟系统,研究了井筒内甲烷气向上运移过程中,不同粒径及不同质量分数疏水纳米SiO_(2)对水合物形成的影响规律。实验结果表明:粒径30 nm与50 nm的疏水纳米SiO_(2)在质量分数为0.1%~2.5%范围内对水合物形成有促进作用;随着疏水纳米SiO_(2)质量分数的增加,诱导时间缩短,气体平均消耗速率总体呈增大趋势;相同质量分数下,粒径为50 nm比粒径为30 nm的疏水纳米SiO_(2)促进作用更为显著。疏水纳米SiO_(2)对水合物形成的促进作用可能是由于其疏水特性,以及增加了溶液的传热传质作用引起。上述结果表明疏水纳米颗粒并不适用于水合物钻井液体系,未来可以考虑加入亲水纳米颗粒,发挥纳米SiO_(2)优势的同时降低水合物聚集风险。

Effect of different particle sizes and mass fraction of hydrophobic nano-SiO_(2)on the hydrate formation during upward migration of methane gas were studied by using dynamic hydrate formation simulation system in borehole.The results show that the addition of hydrophobic nano-SiO_(2)with mass fraction of 0.1%~2.5%and particle sizes of 30 and 50 nm can promote the hydrate formation.Both the induction time and the average gas consumption rate increased with the increase of nanoparticle mass fraction.The promoting effect of hydrophobic nano-SiO_(2)with a particle size of 50 nm is more significant than that of 30 nm under a certain mass fraction.This may be due to the hydrophobic properties of nanoparticles and the increase of heat and mass transfer of solution by adding hydrophobic nano-SiO_(2).The results indicate that hydrophobic nano-SiO_(2)is not suitable for hydrate drilling fluid system.In the future,it can be considered to add hydrophilic nanoparticles to play the advantages of nano-SiO_(2)and reduce the risk of hydrate aggregation.