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| 微裂缝对致密多孔介质中气体渗流的影响机制 |
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赵建林1,姚军1,张磊1,杨永飞1,孙海1,孙致学1,白玉湖2
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(1.中国石油大学石油工程学院,山东青岛 266580;2.中海油研究总院,北京 100028)
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| 摘要: |
| 采用考虑正则化过程的微尺度格子Boltzmann模型研究微裂缝对致密多孔介质中气体渗流的影响机制。首先采用漫反射滑移边界条件，并考虑正则化过程构建适用于高努森数下多孔介质中气体流动模拟的微尺度格子Boltzmann模型，基于该模型进行二维裂缝性致密多孔介质中的气体流动模拟，研究微裂缝对致密多孔介质中气体渗流的影响，并构建二维并联孔隙模型模拟揭示微裂缝对致密多孔介质气体渗流的影响机制。结果表明：微裂缝的存在能够明显提高致密多孔介质的渗透率，且连通性裂缝的影响更明显；随着压力的升高，微裂缝提高致密介质气体渗透率的作用增强，随着压力减小，基岩与裂缝中的气体流速差别减小，基岩对多孔介质渗透率的贡献增加，当压力极大或极小时，裂缝与基岩中平均流速比趋于定值，微裂缝的影响趋于稳定；微裂缝能够提高致密多孔介质渗透率的主要原因是在压降方向上微裂缝与基岩形成了并联高渗通道。 |
| 关键词: 格子Boltzmann方法 致密多孔介质 微裂缝 微尺度效应 |
| DOI：10.3969/j.issn.1673-5005.2018.01.011 |
| 分类号:TE311 |
| 文献标识码:A |
| 基金项目:国家自然科学基金项目（51234007，51490654，51404291，51504276，51674280，51711530131）；高等学校学科创新引智计划项目（B08028）；中央高校基本科研业务费专项（17CX05003）；中海石油（中国）有限公司综合科研项目（YXKY-2016-ZY-03） |
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| Effects of micro-fractures on gas flow in tight porous media |
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ZHAO Jianlin1, YAO Jun1, ZHANG Lei1, YANG Yongfei1, SUN Hai1, SUN Zhixue1, BAI Yuhu2
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(1.School of Petroleum Engineering in China University of Petroleum, Qingdao 266580, China;2.CNOOC Research Institute, Beijing 100028, China)
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| Abstract: |
| In this paper, a microscale lattice Boltzmann (LB) model with a regularization procedure was adopted to investigate the effects of micro-fractures on gas flow in tight porous media. By adopting a diffuse reflection boundary condition and the regularization procedure, the microscale LB model was established, which is suitable to simulate gas flow in porous media with high Knudsen numbers. The mechanisms of gas flow in fractured tight porous media were also analyzed. Finally, a parallel slit pore model was established to investigate the influencing mechanisms of micro-fractures on gas flow in tight porous media.The simulation results show that the micro-fractures can significantly improve the permeability of the tight porous media and the effects of interconnected micro-fractures are more obvious. With the increase of pressure, the effects of micro-fractures increase, and the effects of micro-fractures tend to be stable at both high pressure and low pressure conditions. With the decrease of pressure, the difference of gas flow velocity in fractures and matrix becomes small, and the matrix contributes more to the permeability of the porous media. At relatively high pressures and low pressure conditions, the average velocity ratio in fractures and matrix also tends to be stable. The micro-fractures behave as high permeable channels parallel to the matrix in pressure decreasing directions, so they can significantly increase the permeability of the porous media. |
| Key words: lattice Boltzmann method tight porous media micro-fractures microscale effect |
