一种便捷、可视化的CO2驱助混剂评价方法——高度上升法及其在油田化学中的应用

A Convenient and Visualized Method to Estimate CO2 Miscible Flooding Assistant--Rising Height Test and Its Applications in Oilfield Chemistry

在超临界二氧化碳提高石油采收率技术(CO2-EOR)中,开发有效降低最低混相压力的助混剂是重要的一环。为有效缩短助混剂开发周期,大幅提高开发效率,介绍了一种便捷、可视化的最低混相压力测定方法——高度上升法。利用自行搭建的具有视窗的高压釜设备,将混相过程中油相的体积膨胀转化为高度信息,经数据处理获得混相百分比-平衡压力曲线,整个过程是可视化的,测得的最低混相压力与利用细管实验法测得的数据进行比对以确定准确性;提出了利用不同组成的模拟油进行助混剂筛选的实验方法。结果表明,高度上升法测定最低混相压力与细管实验法测定的相对误差小于5%。利用此方法筛选出了有效的八酯型助混剂,施用于长庆、新疆、吉林的原油样品时,在50数80℃、1%数3%用量下,均可有效降低最低混相压力,最大降幅超过20%。该方法可以准确测定最低混相压力,进而评价助混剂的助混效果。

In the technologies of supercritical CO2 flooding enhanced oil recovery,the development of assistant which can effectively reduce minimum miscibility pressure(MMP)is significantly important.In order to shorten development period and raise efficiency remarkably,a convenient and visualized method to measure MMP,namely rising height test,was introduced.A high pressure cell with transparent windows was set up and by transforming volume expansion of oil phase into height data,a miscible-ratio curve against equilibrium pressure would be obtained after data processing.The whole process could be visualized.The measurement results by this method were compared to those by slim tube test to verify test accuracy.An experiment method which utilized simulation oil samples consisted of different ingredients was introduced for assistant screening.The results showed that the MMP measured by this method was accurate and the relative error was less than 5%compared with that of slim tube test.With this estimation method,an effective octaester assistant was screened out,which was able to reduce the MMP of crude-oil samples from Changqing,Xinjiang and Jilin oilfield under the temperature of 50—80℃and dosage of 1%—3%.The biggest decline was up to 20%.The MMP could be determined accurately by rising height test and the effect of miscible flooding assistant could be estimated.