低渗透油藏CO_2驱与N_2驱室内实验对比研究

为了对比研究CO2驱与N2驱在低渗透油藏的驱油效果,在室内进行了多组长岩心驱替实验。研究结果表明:渗透率相同条件下,CO2驱油效果好于N2。随着渗透率的增加,CO2驱与N2驱的驱油效率增加,但差值越来越小;定速度注入CO2和N2时,注入压力都呈现出先升高后降低,最后趋于平稳的变化趋势;且CO2驱注入压力变化幅度大于N2驱;水驱后转CO2驱或N2驱都能明显降低注入压力,且N2驱降压能力要强于CO2驱;CO2气水交替驱采出程度明显高于连续CO2驱;N2气水交替驱采出程度与连续N2驱相差不大。

Experiment Study of CO2 and N2Flooding in Low Permeability Field

For the comparative study of CO2 and N2 flooding in the low permeability fields,numbers of long core test are experimented in the laboratory.The results are as follows: the displacement characteristics of CO2 flooding is better than N2 under the conditions of same permeability,with the increase of the permeability,both the displacement efficiency of CO2 and N2 are increasing,but the difference is getting smaller and smaller;The trend of pressure increased first and then decreased when the CO2 and N2 were injected by the constant rate and the rangeability of CO2 is bigger than N2;The injection pressure decreased apparently when taking the CO2 and N2 flooding after water flooding and the effect of N2 is better than CO2;The recovery ratio of CO2 WAG is much higher than continuous CO2 flooding,the recovery ratio of N2 WAG is similar with continuous flooding.