页岩油储层超临界CO_(2)吞吐用气溶性表面活性剂性能评价

Performance evaluation of gas soluble surfactants for supercritical CO_(2) huff and puff in shale oil reservoirs

为进一步提高页岩油储层超临界CO_(2)吞吐的效果,采用视窗蓝宝石全自动反应釜、布氏旋转黏度计和高温高压界面张力仪等设备评价了气溶性表面活性剂在超临界CO_(2)中的溶解度,以及降低原油黏度、油气界面张力和最小混相压力的效果,并在此基础之上,利用超临界CO_(2)吞吐实验装置,考察了气溶性表面活性剂对页岩油储层超临界CO_(2)吞吐效果的影响。实验结果表明:FS-320气溶性表面活性剂在超临界CO_(2)中的溶解度最高,在80℃,19.6MPa下溶解度可达1.25%;随着FS-320质量分数的逐渐增大,原油黏度、原油和CO_(2)之间的界面张力以及最小混相压力均呈现逐渐降低的趋势;当FS-320的质量分数为0.5%时,可使原油黏度降低78.95%,最小混相压力由21.3MPa降低至17.2MPa,降低幅度为19.2%;超临界CO_(2)中加入FS-320后,填砂管岩心不同吞吐周期的吞吐效率明显提高,且入口端的压力值也明显升高,4个吞吐周期后的总采收率可达43.56%,与单独超临界CO_(2)吞吐时的33.25%相比提高了10.31百分点。研究结果说明,气溶性表面活性剂的加入可有效提高页岩油储层超临界CO_(2)吞吐的效果,对页岩油藏高效开发具有一定指导意义。

In order to further improve the effect of supercritical CO_(2) huff and puff in shale oil reservoirs,the solubility of gas soluble surfactant in supercritical CO_(2),the effect of reducing crude oil viscosity,the interfacial tension between oil and gas and the minimum miscibility pressure were evaluated by using the window sapphire fully automatic reactor,Brookfield viscometer,high-temperature and high-pressure interfacial tensiometer and other equipment.On this basis,the supercritical CO_(2) huff and puff experimental device was used to investigate the effect of gas soluble surfactant on supercritical CO_(2) huff and puff in shale oil reservoir.The experimental results show that the solubility of gas soluble surfactant FS-320 in supercritical CO_(2) is the highest,and the solubility can reach 1.25%at 80℃and 19.6 MPa.As the mass fraction of FS-320 gradually increases,the viscosity of crude oil,interfacial tension between crude oil and CO_(2),and minimum miscibility pressure all show a decreasing trend.When the mass fraction of FS-320 is 0.5%,the viscosity of crude oil can be reduced by 78.95%,and the minimum miscibility pressure can be reduced from 21.3MPa to 17.2MPa,with a decrease of 19.2%.After FS-320 is added into supercritical CO_(2),the stimulation efficiency of the sand filled core at different cycles was significantly improved,and the pressure value at the inlet also significantly increased.The total recovery rate for four huff and puff cycles can reach 43.56%,which is 10.31 percentage points higher than the 33.25%in comparison with using supercritical CO_(2) alone.The research results show that the addition of gas soluble surfactant can effectively improve the effect of supercritical CO_(2) huff and puff in shale oil reservoirs,which has certain guiding significance for the efficient development of shale oil reservoirs.