无机盐对沥青质稳定性及对分散剂性能的影响

Effect of Inorganic Salts on the Stability of Asphaltene and the Performance of Dispersant

诱发沥青质沉积因素众多,而无机盐及矿物对沥青质稳定性的影响及其与沥青质之间的作用机理尚不明确。针对4个存在沥青质沉积问题油区的原油和沥青质沉积物样品,采用四组分分析、高温模拟蒸馏、傅立叶变换红外光谱和X射线荧光能谱等测试方法,对原油组分组成和元素以及沥青质沉积物元素和水溶液物性参数分别进行了测定和分析,并评价了无机盐对沥青质分散剂性能的影响。实验结果表明:原油样品A发生沥青质沉积是由于原油中含有不稳定沥青质簇,胶体不稳定指数CII值达到1.1。而原油样品B和C则是由于原油被钻完井液污染所致。原油及沥青质沉积物样品中大部分无机元素来源于储层环境,而Br元素则来源于钻完井液中的溴化盐。无机溴盐能够与沥青质分子产生离子-离子或离子-偶极的强引力作用,破坏原油中胶体稳定性。无机盐浓度的降低会削弱无机盐离子对沥青质和分散剂分子之间相互作用的干扰,大幅提升分散剂性能。研究成果可为预防沥青质沉积、缓解沉积伤害提供了参考和借鉴。

There are many factors inducing asphaltene deposition,but the influence and mechanism of inorganic salts and minerals on asphaltene stability are not clear.Aiming at the samples of crude oil and asphaltene sediment in four oil areas with asphaltene deposition problems,the composition and elements of crude oil,the physical parameters of asphaltene sediment elements and aqueous solution were measured and analyzed by four component analysis,high temperature simulated distillation,Fourier transform infrared spectroscopy and X-ray fluorescence spectroscopy,and the effects of inorganic salts on the properties of asphaltene dispersant were evaluated.The experimental results showed that the asphaltene deposition of crude oil sample A was due to the unstable asphaltene clusters in the crude oil,and the colloidal instability index CII value reached 1.1.While the deposition of crude oil samples B and C was caused by the contamination from drilling and completion fluid.Most inorganic elements in crude oil and asphaltene sediment samples came from reservoir,while Br element came from brominated salt in drilling and completion fluid.Inorganic bromine salts could produce strong gravitational action of ion-ion or ion-dipole with asphaltene molecules and destroyed the colloidal stability in crude oil.The decrease of inorganic salt concentration would weaken the interference of inorganic salt ions on the interaction between asphaltene and dispersant molecules,and greatly improved the performance of dispersant.The research results provided a reference for preventing asphaltene deposition and alleviating deposition damage.