大庆原油O/W型乳状液合成球霞石碳酸钙垢及其结垢机理研究

Synthesis and mechanism of vaterite scaling in Daqing crude oil O/W emulsion

大庆油田三元复合驱油技术的应用导致油田开采和集输过程中碳酸钙结垢严重,原油采收率受到严重影响。通过研究大庆脱水脱盐原油O/W型乳状液条件,以Na_2CO_3和CaCl_2为原料,采用三元复合驱组分重烷基苯磺酸盐(HABS)和部分水解聚丙烯酰胺(HPAM)为有机添加剂合成了粒径均一的球霞石碳酸钙垢。采用X射线衍射仪(XRD)、傅里叶红外分析仪(FTIR)和扫描电子显微镜(SEM)对该体系下形成的碳酸钙进行表征。实验结果表明,当c(Na_2CO_3)和c(CaCl_2)均为0.1mol/L,V(油)∶V(水)=1∶3,ρ(HABS)=600mg/L,ρ(HPAM)=200mg/L时,形成O/W型乳状液,在45℃条件下,反应1h,原油体积的空间位阻作用导致奥斯瓦尔德熟化过程中的可溶性碳酸钙在c轴方向重结晶,进而稳定控制合成粒径为1~2μm的球霞石碳酸钙。研究为延缓或减少稳定的结晶相碳酸钙形成,有效抑制结垢等问题提供技术支持。

In Daqing oilfield,the CaCO_3 scaling problem was occurred during the process of exploitation,gathering and transportation owing to the application of ASP flooding technology,which seriously affected the oil recovery efficiency.Well-dispersed vaterite CaCO3 particles were successfully synthesized with heavy alkyl-benzene sulfonate(HABS)and partially hydrolyzed polyacrylamide(HPAM)as organic additives in the Daqing crude oil emulsion,and Na_2CO_3 and CaCl_2 solution were raw materials.The phase composition and morphology of the products were characterized by X-ray diffraction(XRD),fourier transform infrared(FTIR)spectrometer and scanning electron microscopy(SEM).The experiment results showed that pure vaterite calcium carbonate crystals with uniform particle size 1~2μm were obtained in following conditions:the concentration of Na_2CO_3 and CaCl_2 solution were 0.1 mol/L,collectively,the volume ratio of Oil/Water was 1∶3,the concentration of HABS and HPAM were 600 mg/L and 200 mg/L,respectively,and ripening for 1 hat 45℃.During Oswald ripening,CaCO3 particles grow in the c-axes by the steric hindrance of the crude oil,then 1~2μm vaterite calcium carbonate was controllable generated.This study provides technical support for delaying or reducing the formation of stable crystalline calcium carbonate and effectively inhibiting the scaling problems.