在模拟油藏条件下,系统评价超临界CO2 驱增黏体系注入性、油藏环境适应性及均质与非均质岩心驱油效果.结果表明,在油藏温度和压力下,优选构筑的超临界 CO2 驱增黏体系(COAP-1)黏度可达 2.16 mPa·s;CO2/COAP-1黏度随压力增加而逐渐增大,受温度的影响较小;均质与非均质物模实验中,岩心水驱后转注CO2/COAP-1驱相较于 CO2 驱,提高采收率效果更为显著,采收率增幅随着渗透率级差的增加略有提升.CO2/COAP-1体系可有效降低CO2 的流度,堵塞高渗层的微小孔隙,并有效启动低渗透层,扩大波及体积,大幅度提高采收率.
Construction and evaluation of CO2 flooding viscosification system in ultra-low permeability reservoir
Under simulated reservoir conditions,the injectivity,adaptability of reservoir environment,and the effect of homogeneous and heterogeneous core flooding were evaluated.The results show that the vis-cosity of the selected supercritical CO2 flooding and viscosification system(COAP-1)can reach 2.16 mPa·s under reservoir temperature and pressure.The CO2/COAP-1 viscosity increases gradually with the increase of pressure,and is less affected by temperature.In the homogeneous and heterogeneous physical model experiments,CO2/COAP-1 flooding after core water flooding has a more significant effect on enhancing oil recovery than CO2 flooding,and the increase of oil recovery is slightly increased with the increase of permeability.The CO2/COAP-1 system can effectively reduce the mobility of CO2,plug the ti-ny pores of the high permeability layer,effectively start the low permeability layer,expand the swept vol-ume,and greatly improve the recovery rate.
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