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Experimental investigation on stable displacement mechanism and oil recovery enhancement of oxygen-reduced air assisted gravity drainage
Petroleum Exploration and Development ( IF 7.0 ) Pub Date : 2020-08-21 , DOI: 10.1016/s1876-3804(20)60099-4
Xiaolong CHEN , Yiqiang LI , Guangzhi LIAO , Chengming ZHANG , Shanzhi XU , Huan QI , Xiang TANG

The effects of gravity, capillary force, and viscous force on the migration characteristics of oil and gas interface in oxygen-reduced air-assisted gravity drainage (OAGD) were studied through a two-dimensional visualization model. The effects of bond number, capillary number and low-temperature oxidation on OAGD recovery were studied by long core displacement experiments. On this basis, the low-temperature oxidation number was introduced and its relationship with the OAGD recovery was established. The results show that the shape and changing law of oil and gas front are mainly influenced by gravity, capillary force and viscous force. When the bond number is constant (4.52×10−4), the shape of oil-gas front is controlled by capillary number. When the capillary number is less than 1.68×10−3, the oil and gas interface is stable. When the capillary number is greater than 2.69×10−2, the oil and gas interface shows viscous fingering. When the capillary number is between 1.68×10−3 and 2.69×10−2, the oil and gas interface becomes capillary fingering. The core flooding experiments results show that for OAGD stable flooding, before the gas breakthrough, higher recovery is obtained in higher gravity number and lower capillary number. In this stage, gravity is predominant in controlling OAGD recovery and the oil recovery could be improved by reducing injection velocity. After gas breakthrough, higher recovery was obtained in lower gravity and higher capillary numbers, which means that the viscous force had a significant influence on the recovery. Increasing gas injection velocity in this stage is an effective measure to improve oil recovery. The low-temperature oxidation number has a good correlation with the recovery and can be used to predict the OAGD recovery.



中文翻译:

氧还原空气辅助重力排水稳定驱替机理及提高采收率的实验研究

通过二维可视化模型研究了重力,毛细作用力和粘性作用力对氧气减少的空气辅助重力排水(OAGD)中油气界面迁移特征的影响。通过长核位移实验研究了键数,毛细管数和低温氧化对OAGD回收率的影响。在此基础上,引入了低温氧化数,建立了其与OAGD回收率的关系。结果表明,油气锋面的形状和变化规律主要受重力,毛细作用力和粘性作用力的影响。当键数恒定(4.52×10 -4)时,通过毛细数控制油气前沿的形状。当毛细管数小于1.68×10 -3时,油气界面稳定。当毛细管数大于2.69×10 -2时,油气界面显示出粘性指状。当毛细管数在1.68×10 -3和2.69×10 -2之间,油气界面变成毛细管指状。岩心驱油实验结果表明,对于OAGD稳定驱油,在天然气突破之前,以较高的重力值和较低的毛细管数可获得较高的采收率。在此阶段,重力是控制OAGD采收率的主要因素,可以通过降低注入速度来提高采油率。气体突破后,在较低的重力和较高的毛细管数下可获得较高的采收率,这意味着粘性力对采收率有重大影响。在这一阶段增加注气速度是提高采油率的有效措施。低温氧化值与回收率具有良好的相关性,可用于预测OAGD的回收率。

更新日期:2020-08-21
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