高温高压下离子液体对原油中沥青质沉淀的抑制效果评价

Inhibition Effect Evaluation of Ionic Liquid on Asphaltene Precipitation in Crude Oil under High Temperature and Pressure

离子液体在油藏开发中防止沥青质沉淀的潜力较大,但高温高压条件下离子液体的抑制效果尚不明确。在对2种离子液体氯化1-丁基-3-甲基咪唑([bmim]Cl)和溴化1-丁基-3-甲基咪唑([bmim]Br)以及2种商业抑制剂对原油中沥青质沉淀抑制效果评价的基础上,采用其中的最佳抑制剂及浓度开展了高温高压沥青质沉淀测定实验,研究了离子液体对地层原油及CO_(2)注入后地层原油中沥青质沉淀起始压力(AOP)及沥青质聚集体尺寸的影响。结果表明,[bmim]Br对沥青质沉淀的抑制效果远高于[bmim]Cl和另外2种商业抑制剂,最佳加量为600 mg/L。纯地层原油的AOP为28.7 MPa;当加入[bmim]Br后,AOP降幅为21.6%;当在离子液体中添加异丙醇后,AOP降幅达到29.6%。饱和30%CO_(2)地层原油的AOP为31.6 MPa;当加入异丙醇与[bmim]Br的混合溶剂时,AOP降幅达44.3%。异丙醇能与[bmim]Br及CO_(2)产生三元相互作用,提高[bmim]Br的活性,大幅降低饱和CO_(2)原油的AOP,减缓沥青质颗粒粒径的增长速度,降低沥青质在井筒中的沉积深度和堵塞程度,将沥青质沉积引入更易控制的节点,具有广阔的应用前景。

Ionic liquids have great potential to prevent asphaltene precipitation in reservoir development,but the inhibition effect of ionic liquids under high temperature and pressure is not clear.Based on the inhibition effects of two ionic liquids,such as 1-butyl-3-methylimidazole chloride([bmim]Cl)and 1-butyl-3-methylimidazole bromide([bmim]Br),and two common commercial inhibitors on asphaltene precipitation in crude oil,the determination experiments of asphaltene precipitation at high temperature and pressure were carried out under the best inhibitor and ratio concentration.The effects of ionic liquids on the initial pressure of asphaltene precipitation(AOP)and the size of asphaltene aggregate in formation crude oil and CO_(2) injected formation crude oil were studied.The results showed that the inhibition effect of[bmim]Br on asphaltene precipitation was much higher than that of[bmim]Cl and two other commercial inhibitors.The optimum dosage was 600 mg/L.The AOP of pure formation crude oil was 28.7 MPa.After[bmim]Br was added,the AOP dropped by 21.6%.When isopropanol was added to ionic liquid,the AOP dropped by 29.6%.The AOP of formation crude oil saturated with 30% CO_(2) was 31.6 MPa.When isopropanol and ionic liquid mixed solvent was added,the AOP dropped by 44.3%.Isopropanol could produce ternary interaction with[bmim]Br and CO_(2),improve the activity of[bmim]Br,greatly reduce the AOP of saturated CO_(2) crude oil,slow down the growth rate of asphaltene particle size,reduce the deposition depth and blockage degree of asphaltene in the wellbore,and then introduce asphaltene deposition into more controllable nodes,which had broad application prospects.