Wang Han, Cai Jianchao, Su Yuliang, Jin Zhehui, Zhang Mingshan, Wang Wendong, Li Guanqun
National Key Laboratory of Petroleum Resources and Engineering, China University of Petroleum, Beijing 102249, P. R. China.
Key Laboratory of Unconventional Oil & Gas Development (China University of Petroleum (East China)), Ministry of Education, Qingdao 266580, P. R. China.
Langmuir. 2023 Aug 29;39(34):12226-12234. doi: 10.1021/acs.langmuir.3c01570. Epub 2023 Aug 15.
Due to the fracturing fluid imbibition and primary water, oil-water two-phase fluids generally exist in shale nanoporous media. The effects of water phase on shale oil recovery and geological carbon sequestration via CO huff-n-puff is non-negligible. Meanwhile, oil-CO miscibility after CO huff-n-puff also has an important effect on oil-water two-phase flow behaviors. In this work, by considering the oil-CO competitive adsorption behaviors and the effects of oil-CO miscibility on water wettability, an improved multicomponent and multiphase lattice Boltzmann method is proposed to study the effects of water phase on CO huff-n-puff. Additionally, the effects of oil-CO miscibility on oil-water flow behaviors and relative permeability are also discussed. The results show that due to Jamin's effect of water droplets in oil-wetting pores and the capillary resistance of bridge-like water phase in water-wetting pores, CO can hardly diffuse into the oil phase, causing a large amount of remaining oil. As water saturation increases, Jamin's effect and the capillary resistance become more pronounced, and the CO storage mass gradually decreases. Then, based on the results from molecular dynamics simulations, the influences of oil-CO miscibility on oil-water relative permeability in calcite nanoporous media are studied, and as the oil mass percentage in the oil-CO miscible system decreases, the oil/water relative permeability decreases/increases. The improved lattice Boltzmann model can be readily extended to quantitatively calculate geological CO storage mass considering water saturation and calculate the accurate oil-water relative permeability based on the real 3D digital core.
由于压裂液吸入和原生水的存在，油-水两相流体通常存在于页岩纳米孔隙介质中。水相对页岩油采收率以及通过CO吞吐进行地质碳封存的影响不可忽视。同时，CO吞吐后油与CO的混相性对油-水两相流行为也有重要影响。在这项工作中，通过考虑油与CO的竞争吸附行为以及油-CO混相性对水润湿性的影响，提出了一种改进的多组分多相格子玻尔兹曼方法来研究水相对CO吞吐的影响。此外，还讨论了油-CO混相性对油-水流动行为和相对渗透率的影响。结果表明，由于油湿孔隙中水滴的贾敏效应以及水湿孔隙中桥状水相的毛细管阻力，CO很难扩散到油相中，导致大量剩余油。随着含水饱和度的增加，贾敏效应和毛细管阻力变得更加明显，CO储存量逐渐减少。然后，基于分子动力学模拟结果，研究了油-CO混相性对方解石纳米孔隙介质中油-水相对渗透率的影响，随着油-CO混相体系中油质量百分比的降低，油/水相对渗透率降低/升高。改进的格子玻尔兹曼模型可以很容易地扩展，以考虑含水饱和度定量计算地质CO储存量，并基于真实的三维数字岩心计算准确的油-水相对渗透率。
