Two-phase oil/water seepage in fractured granite rock mass: Insight from seepage visualization experiment and numerical simulation

被引：0
|
作者：
Sun Z. [1 ]
Zhang B. [1 ,2 ]
Chen D. [1 ]
Li Y. [1 ]
Wang H. [1 ,2 ]
机构：
[1] School of Engineering and Technology, China University of Geosciences (Beijing), Beijing
[2] Technology Innovation Center for Major Engineering Geological Safety Risk Prevention and Control, Ministry of Natural Resources, Beijing
来源：
Earth Science Frontiers | 2023年 / 30卷 / 03期
关键词：
3D printing technology; granite; multiphase flow device; numerical simulation; oil-water displacement; rough fracture; visualization experiment;
D O I：
10.13745/j.esf.sf.2022.12.54
中图分类号：
学科分类号：
摘要：
Hard rock caverns used for underground oil storage are mostly constructed in crystalline rock mass and water sealed, thus the seepage characteristics of the rock mass directly affect the safety of oil storage. The challenge of water sealing in underground caverns can be simplified to the problem of two-phase oil/water seepage through fractures in the surrounding rock mass, so it is necessary to consider both oil and water displacements to addressing this challenge. In this study, seepage visualization experiment and numerical simulation were carried out on fractured natural granite. The fracture roughness was quantified by fractal analysis, and transparent fractures with different roughness values were prepared by 3D printing. Physical model test was carried out by using the home-built single-fracture multiphase-seepage visualization device, and fluid displacement in rough fractures was studied by numerical simulation. Difference in the mobility ratio (water to oil) leads to different two-phase (oil-water) flow dynamics, where the oil-flooding front moves as piston flow while water-flooding front as fingered flow. In oil displacement, the increase of fluid pressure or fracture width can significantly improve oil displacement efficiency, whereas increasing fracture roughness hinders oil flow and impedes oil displacement. Considering the relevance of fracture roughness and oil viscosity, safety requirements for water sealing are not adequate if only fluid pressure is considered. Due to Jamin effect, it is difficult to remove oil completely from rock fractures by water flooding, or to recover leaked oil. The research results provide a reference for understanding two-phase seepage in rough fractures in rocks and water sealing mechanism in underground caverns. © 2023 Science Frontiers editorial department. All rights reserved.
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页码：465 / 475
页数：10
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