原地自生封堵转向酸的研究

利用酸化材料自身水解及水解产物与钙离子发生沉淀反应的原理,研制出了一种新型转向酸。对该转向酸进行了溶蚀实验、静态腐蚀速率、酸液驱替及渗透率以及残酸界面张力等测定,并采用SEM和XRD检测手段对酸液转向机理进行了分析。研究结果表明:该转向酸比盐酸具有更好的缓速性及低腐蚀性,在中低渗碳酸盐岩心中转向能力达到15%,为盐酸的5倍以上,且转向酸残酸的黏度接近清水、油水界面张力低于10 m N/m,能顺利返排。SEM和XRD检测手段结果表明,该转向酸可在岩石表面产生少量二水硫酸钙微溶物,延缓酸岩反应,从而促使酸液向低渗储层转向。该原地自生封堵转向酸可实现酸液就地转向,达到均匀布酸目的。

Study on In-situ Authigenic Sealing Diverter Acid

A new diverter acid was developed through precipitation reaction between the hydrolysis product of acid chemicals and calcium ions. Laboratory study on the diverter acid showed that this diverter acid had better retarding performance and lower corrosivity than hydrochloric acid. Testing of the diverter acid on medium to low permeability carbonate rock samples showed a diverting capacity of 15%, five times that of hydrochloric acid; the viscosity of the residue diverter acid was almost equal to that of clear water, and the oil-water interfacial tension was less than 10 mN/m, meaning that the diverter acid can be easily removed by backflow. Experiment on the diverter acid with SEM and XRD showed that the diverter acid produced some calcium sulphate (CaSO4·2H2O), which retarded the reaction between acid and rocks, thus pushed the flow of the acid to low permeability area. The use of in-situ authigenic sealing diverter acid makes an even distribution of the acid fluid.