烟道气辅助注蒸汽开采稠油增效机理及应用

Mechanism and application of flue gas-assisted steam injection for heavy oil recovery

烟道气作为辅助剂可改善蒸汽开发稠油的效果。为探究烟道气与不同相态蒸汽协同作用下的增产机制、推动烟道气在油田的规模化应用,通过控制一维驱油实验参数,系统研究烟道气对蒸汽/热水驱油特征的影响,利用二维可视化实验探究烟道气对蒸汽腔扩展规律及驱油生产动态的影响,并开展烟道气辅助蒸汽吞吐现场试验,对效果进行了验证。研究结果表明,烟道气能显著提高蒸汽的驱油效率;当蒸汽为液态时,烟道气将液相转变为气液两相,改善微观波及效果,且随着温度升高,烟道气增效作用变强;当蒸汽为汽态时,烟道气改善蒸汽的干度,大幅提高蒸汽与稠油的接触程度和热利用效率,但是随着温度升高,烟道气增油效果减弱;烟道气发挥作用的优势区域在汽—液相态边界处,驱油效率增幅可达24.2%。烟道气促进蒸汽驱过程中蒸汽腔中下部的发育,使蒸汽腔波及系数提高17.4%,采收率提高25.4%。现场应用25井次,平均周期增油量为120 t,油汽比提高0.1,典型井周期增油量为775 t,油汽比由0.3提高到0.9。

Flue gas,used as an additive,can enhance the efficiency of steam flooding for heavy oil.To investigate the enhanced oil recovery mechanism of flue gas in collaboration with different phases of steam,and promote the large-scale application of flue gas in oil fields,the influence of flue gas on steam/hot water oil displacement characteristics was systematically studied by regulating 1D experimental parameters.Later,2D visualization experiments were conducted to explore the impact of flue gas on the expansion law of steam chamber and oil displacement and production performance,the effect of which was verified by the field experiment of flue gas-assisted steam huff and puff.The results show that flue gas can significantly improve the efficiency of steam flooding.When the steam is in a liquid state,the liquid phase of flue gas is transformed into gas and liquid phases,improving the microscopic sweep efficiency;as the temperature rises,the synergistic effect of flue gas becomes stronger.When the steam is in a vapor state,flue gas can improve the dryness of steam,and significantly increase the contact degree between steam and heavy oil,as well as the thermal utilization efficiency.However,as the temperature rises,the oil displacement effect achieved by flue gas diminishes.The advantageous region where flue gas plays a dominant role is at the vapor-liquid phase boundary,and the oil displacement efficiency can increase up to 24.2%.Flue gas promotes the development of the middle and lower parts of the steam chamber during steam flooding,resulting in a 17.4%increase in the sweep coefficient of steam chamber and a 25.4%increase in oil recovery.In field applications for over 25 well times,the average oil production is increased by 120 t per cycle,and the oil-to-steam ratio is increased by 0.1.In typical wells,the oil production is increased by 775 t per cycle,and the oil-to-steam ratio is increased from 0.3 to 0.9.