低渗透油藏ASG复合泡沫体系注入参数优化

Optimization of Injection Parameters for ASG Composite Foam System in Low Permeability Reservoirs

对ASG(碱、表面活性剂与氮气)复合泡沫体系与水交替注入提高采收率技术在高温高矿化度低渗透油藏的适用性进行研究。通过室内驱油实验的方法,开展ASG泡沫与水交替注入实验,并将之与水驱、氮气驱、表面活性剂驱进行对比。结果发现,ASG泡沫与水交替注入较水驱、氮气驱、表面活性剂驱分别采收率提高了16.61%、10.26%与9.21%。ASG泡沫与水交替注入的注入参数优化实验研究结果表明,在累积注入泡沫体积相同(1.2倍孔隙体积)的条件下,采用0.4倍孔隙体积泡沫段塞交替注入的效果最佳;泡沫注入速度的最优值为1.5mL/min,当注入速度过低时,产生泡沫较少,且容易发生气液分离,封堵效果不佳,当注入速度过高时,泡沫大小不一,容易发生气泡合并,引起气泡的破裂,同时容易造成泡沫的剪切消泡;分三次注入段塞气液质量比分别为3∶1、2∶1与1.5∶1时,较单一气液质量比泡沫采收率提高了2.04%。

The enhanced oil recovery technology of ASG（alkali,surfactant and nitrogen）composite foam and water alternating injection was studied in high temperature and high salinity low permeability reservoir.The ASG foam and water alternating injection experiments were carried out through indoor flooding experiments,and compared with water flooding nitrogen flooding and surfactant flooding.The results show that the enhanced oil recovery of the method adopted by this study is 16.61%,10.26% and 9.21%,respectively,compared with water flooding,nitrogen flooding and surfactant flooding technology.Experimental study on injection parameters optimization of ASG foam and water alternating injection is carried out,and the parameters such as slug size,injection rate and gas fluid ratio of ASG composite foam are optimized by bench scale displacement test.The results show that under the condition of the same foam injection volume（1.2 times the pore volume）,the effect of foam slug injection with 0.4 times pore volume is best.The foam injection rate has an optimum value of 1.5 mL/min.When the injection rate is too low,less foam is produced,gas-liquid separation is easy to occur,and the blocking effect is poor.When the injection rate is too high,the size of the bubble is different,and it is easy to cause the bubble to merge,causing the bubble to burst,and at the same time,it is easy to cause the shear defoaming of the foam.When the gas fluid ratio is 3∶1,2∶1 and 1.5∶1,respectively,the recovery rate is 2.04% higher than that of the single gas fluid ratio.