低渗透稀油油藏水驱后氮气泡沫驱适应性

吐哈油田低渗透稀油油藏注水开发进入高含水期后,水淹程度高,水驱调整措施效果较差,亟需寻找后续提高采收率方法。针对低渗透油藏注入能力差、不适合注聚合物等高黏度流体的特点,利用水驱、氮气泡沫驱和水驱后氮气泡沫驱开展室内实验研究,探讨驱油效率及其影响因素。结果表明,水驱驱油效率随渗透率的增加而升高,与渗透率呈较好的对数关系;氮气泡沫驱驱油效率为67.66%,较水驱驱油效率提高10.62%;氮气泡沫驱可在水驱的基础上提高驱油效率约9.63%。实验用泡沫的残余阻力系数大于1,表明氮气泡沫驱通过堵水调剖,提高了水驱后油藏的采收率,从机理和实验提高驱油效率程度判断,氮气泡沫驱适用于吐哈油田低渗透稀油油藏。

Adaptability Evaluation of Nitrogen Foam Flooding After Water-Flooding in Low-Permeability Light Oil Reservoirs

After water-flooding development, the low-permeability light oil reservoirs have entered a stage of high water cut, and the reservoirs have been seriously water-flooded in Tuha oilfield, so no water flooding measures seem effective. To improve the recovery, it is urgent to find other EOR technologies. Since high-viscosity fluid (i.e. polymer) is not applicable for the low-permeability reservoirs, laboratory experiments were carried out to investigate the oil displacement efficiency and its influencing factors based on water flooding, nitrogen foam flooding and nitrogen foam flooding after water flooding. The experimental results show that the oil displacement efficiency by water flooding increases with the increase of reservoir permeability and has a better logarithmic relationship with the permeability; the nitrogen foam flooding efficiency is 67.66%, which is 10.62% higher than that of water-flooding; nitrogen foam flooding after water flooding can improve the oil displacement efficiency by about 9.63% on the basis of water flooding. The residual resistance factor of the foam used in the experiments is greater than 1, which indicates that the recovery after water-flooding has been increased by using nitrogen foam with water plugging and profile modification. It is concluded that the nitrogen foam flooding is suitable for the low-permeability light oil reservoirs according to its mechanism and experimental results in Tuha oilfield.