Bai Yu, Liu Jianbo, Liu Shangqi, Xia Zhaohui, Chen Yuxin, Liang Guangyue, Shen Yang
PetroChina Research Institute of Petroleum Exploration & Development, Beijing 100083, China.
Department of Chemical and Petroleum Engineering, University of Calgary, Calgary, Alberta T2N 1N4, Canada.
ACS Omega. 2021 Aug 18;6(34):22333-22343. doi: 10.1021/acsomega.1c03090. eCollection 2021 Aug 31.
Hot solvent-assisted gravity drainage (HS-AGD) is an effective way to exploit oil sands and heavy oil both economically and environmentally. The visualized microscopic seepage experiments and two-dimensional (2-D) macroscopic simulation experiments of HS-AGD are carried out, and the results are compared with that of steam-assisted gravity drainage (SAGD) in detail for the first time in order to compare their development effects of the oil sand reservoir. MacKay River oil sand bitumen is taken as an oil sample in the experiments, with -hexane as the solvent. Micro seepage characteristics of the hot solvent and steam and the remaining oil distribution of the solvent and steam drive are investigated through microseepage experiments. The expanding process of the solvent/steam chamber and production performance of HS-SAGD and SAGD are investigated through macrosimulation experiments. The study found that the sweep efficiency of hot solvent is higher than that of steam at the same temperature due to the small interfacial tension between the condensed solvent and heated bitumen. Due to the severe gravity segregation, the steam accumulated at the top of the model during the 2-D physical simulation experiment, which results in the huge heat loss at the top of the model. The temperature of the steam chamber is significantly lower than that of the solvent chamber. The oil recovery of 200 °C hot solvent vapor is twice as much as that of 300 °C steam owing to the different drainage mechanisms of the HS-AGD and SAGD. In SAGD, only heat transfer reduces the viscosity of oil sand bitumen. The components of oil produced in SAGD have little difference compared with that of the original bitumen. In HS-AGD, both mass transfer and the sensible heat transfer reduce the viscosity of oil sand bitumen. The in situ asphaltene precipitation induced by heated-solvent extraction also upgrades the bitumen. The results of component analysis show that in HS-AGD, the content of heavy components in the oil sand bitumen is obviously reduced. This paper aims to reveal the oil drainage mechanism of HS-AGD and SAGD from the macroscopic and microscopic view and to provide theoretical guidance for the field application of this technology.
热溶剂辅助重力泄油（HS - AGD）是一种在经济和环境方面都能有效开采油砂和稠油的方法。开展了HS - AGD的可视化微观渗流实验和二维（2 - D）宏观模拟实验，并首次将结果与蒸汽辅助重力泄油（SAGD）的结果进行了详细比较，以对比它们对油砂储层的开发效果。实验中以麦凯河油砂沥青为油样，以正己烷为溶剂。通过微观渗流实验研究了热溶剂和蒸汽的微观渗流特性以及溶剂和蒸汽驱的剩余油分布。通过宏观模拟实验研究了溶剂/蒸汽腔的扩展过程以及HS - SAGD和SAGD的生产性能。研究发现，由于冷凝溶剂与加热沥青之间的界面张力较小，在相同温度下热溶剂的波及效率高于蒸汽。在二维物理模拟实验中，由于严重的重力分异，蒸汽积聚在模型顶部，导致模型顶部热量大量损失。蒸汽腔的温度明显低于溶剂腔的温度。由于HS - AGD和SAGD的泄油机制不同，200℃热溶剂蒸汽的采油量是300℃蒸汽采油量的两倍。在SAGD中，只有热传递降低油砂沥青的粘度。SAGD产出油的成分与原始沥青相比差异不大。在HS - AGD中，传质和显热传递都降低了油砂沥青的粘度。热溶剂萃取引起的原地沥青质沉淀也使沥青得到了升级。成分分析结果表明，在HS - AGD中，油砂沥青中重组分的含量明显降低。本文旨在从宏观和微观角度揭示HS - AGD和SAGD的泄油机理，为该技术的现场应用提供理论指导。
