二氧化碳与稠化剂降低流度改善气驱效果评价

由于地层条件复杂、非均质性严重,天然或人工裂缝发育及CO₂本身存在的不利流度比等因素,造成CO₂气窜严重,采收率低。为了降低气体流度、改善CO₂驱替效果,YC油田根据CO₂性质提供了一种线性嵌段共聚物稠化剂。通过室内模拟YC油田区块,对稠化剂/CO₂体系进行了剪切流变性、高温高压流变性静态评价;再结合二维岩心、三维三轴模型驱油实验,动态评价了稠化剂/CO₂体系的驱油效果。结果表明,稠化剂与CO₂形成的体系在40数80℃具有良好的稳定性,可增大CO₂黏度(0.014 mPa·s)约20倍。温度对稠化剂/CO₂体系黏度的影响较小。随剪切速率增加,稠化剂/CO₂体系黏度减小;随着压力的增加,稠化剂/CO₂体系的黏度逐渐增大。在模拟地层条件下,稠化剂/CO₂体系具有良好的降低CO₂流度和改善气驱效果的作用。对于非...

Effect of Thickener and Carbon Dioxide System on Mobility Reduction and Gas Flooding Improvement

Due to the complex formation conditions,serious heterogeneity,the development of natural or artificial fractures,and adverse mobility ratio of CO2,thus CO2 gas channeling is serious and the recovery factor is low.In order to reduce the gas mobility and improve the effect of CO2 flooding,YC oilfield provided a linear block copolymer thickener based on the property of CO2.The shear rheological property,high temperature and high pressure rheological property of the thickener/CO2 system were evaluated by simulating YC oilfield block.Combined with two-dimensional core and three-dimensional triaxial model experiments,the oil displacement effect of thickener/CO2 system was evaluated dynamically.The results showed that the system formed by thickener and CO2 had good stability at 40—80℃,which could increase the viscosity of CO2(0.014 mPa·s)by about 20 times.Temperature had little effect on the viscosity of thickener/CO2 system.As the shear rate increased,the viscosity of thickener/CO2 system decreased.While as the pressure increased,the viscosity of thickener/CO2 system gradually increased.Under simulated formation conditions,the thickener/CO2 system had a good effect on reducing CO2 mobility and improving gas flooding.For heterogeneous cores,the enhanced recovery factor(13.75%)for cores with small permeability differences was greater than that(11.98%)for cores with large permeability differences.For homogeneous cores,the thickener/CO2 system could effectively improve the problem of serious CO2 channeling,further develop CO2 displacement effect and greatly increase the recovery factor of crude oil.