致密油藏直流电提高采收率技术实验研究

Experimental Study on Direct Current Enhanced Oil Recovery Technology for Tight Reservoirs

针对致密油注水困难导致开发效果较差的问题,提出应用直流电场提高致密油采收率。以鄂尔多斯盆地上三叠统延长组致密砂岩岩心为研究对象,通过直流电场恒速驱替实验、润湿角测量及XRD测试实验,探究直流电场驱替效果及作用机理。研究表明:致密油采用直流电场的采收率与电场强度正相关;水驱开始时应用直流电场的开发效果优于水驱结束后应用直流电场,两者在10 V电压下分别可将水驱平均采收率提高29.06个百分点和14.68个百分点;应用直流电场后,采油速度加快;直流电场不但可以通过电渗流减小流动阻力,降低注水难度,还可通过电化学反应增强岩石的亲水性,提高驱油效率。该研究为致密油高效开发提供了新的思路。

To address the problem of poor development due to difficult water injection in tight oil,the application of DC electric field is proposed to enhance the recovery of tight oil.Taking the tight sandstone core of the Upper Triassic Yanchang Formation in the Ordos Basin as the research object,the DC electric field displacement effect and the mechanism of action were investigated through DC electric field constant velocity displacement experiments,wetting angle measurements and XRD test experiments.The study shows that the DC electric field enhanced recovery rate of tight oil is positively correlated with the electric field intensity;the development effect when the DC electric field is applied at the beginning of water flooding is better than that when the DC electric field is applied after the end of water flooding,both of which can increase the average recovery rate through water flooding by 29.06 and 14.68 percentage points respectively at 10 V;the recovery rate is accelerated after the DC electric field is applied;the DC electric field can not only reduce the flow resistance through electroosmotic flow to decrease the difficulty of water injection,but also enhance the hydrophilicity of the rock through electrochemical reaction to improve the oil displacement efficiency.The study provides a new idea for the efficient development of tight oil.