非均质特低渗油藏CO_(2)驱增黏体系构筑及驱油效果研究

Construction and evaluation of CO_(2) flooding viscosification system in ultra-low permeability reservoir

在模拟油藏条件下,系统评价超临界CO_(2)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CO_(2)驱增黏体系(COAP-1)黏度可达2.16 mPa·s;CO_(2)/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CO_(2)/COAP-1驱相较于CO_(2)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。CO_(2)/COAP-1体系可有效降低CO_(2)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。

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 viscosity of the selected supercritical CO_(2) flooding and viscosification system(COAP-1)can reach 2.16 mPa·s under reservoir temperature and pressure.The CO_(2)/COAP-1 viscosity increases gradually with the increase of pressure,and is less affected by temperature.In the homogeneous and heterogeneous physical model experiments,CO_(2)/COAP-1 flooding after core water flooding has a more significant effect on enhancing oil recovery than CO_(2) flooding,and the increase of oil recovery is slightly increased with the increase of permeability.The CO_(2)/COAP-1 system can effectively reduce the mobility of CO_(2),plug the tiny pores of the high permeability layer,effectively start the low permeability layer,expand the swept volume,and greatly improve the recovery rate.