摘要
以往的研究多是从宏观层面建立孔隙压缩敏感性与渗透率之间的关系,缺乏砂岩不同尺度孔隙结构改变对渗透率演化规律的认识。从细观孔隙层面来看,不同尺度孔隙在应力作用下闭合程度差异明显,考虑不同尺度下孔隙压缩敏感性对准确预测渗透率演化至关重要。因此,利用多场耦合核磁共振试验平台开展了砂岩渗流-应力耦合试验,获得了不同应力作用下砂岩渗透率以及孔径分布曲线的变化规律,将孔径分成大孔(>1μm)、中孔(0.1~lμm)、小孔(<0.1μm)3类,计算了砂岩不同尺度孔隙压缩系数及其转化因子,提出了考虑不同尺度孔隙压缩敏感性的砂岩渗透率计算公式。结果发现:砂岩不同尺度孔隙的压缩性差异明显,大尺度孔隙的压缩敏感性更强;考虑不同尺度孔隙压缩敏感性的渗透率公式与试验值具有较好的一致性。
Most previous studies focused on establishing the relationship between pore compression sensitivity and permeability at the macroscopic level. However, the effect of different pore-structures at multi-scales on the evolution of permeability characteristics is still not clear. Also, many mesoscopic studies have showed that the closure degree of pores at multi-scales are significantly different under the action of stress. Thus, the pore compression sensitivity at different scales is crucial to predict the evolution of permeability accurately. In this study, the hydro-mechanical experiments of sandstone were performed using a multi-field coupling NMR experimental system to obtain the variations of permeability and pore-size distribution under different stress conditions. The pore diameter is divided into three categories: large pore(>1 μm), middle pore(0.1–1 μm), and small pore(<0.1 μm). The pore compressibility coefficients at different scales and transforming factors were calculated. A calculation formula for sandstone permeability considering pore compression sensitivity at different scales was also proposed. The results show that the compressibility of pores at different scales of sandstone is significantly different. The larger the pores are, the higher the compression sensitivity is.The proposed permeability formula considering the pore compression sensitivity at different scales are in good agreement with the experimental results.
作者
田佳丽
王惠民
刘星星
向雷
盛金昌
罗玉龙
詹美礼
TIAN Jia-li;WANG Hui-min;LIU Xing-xing;XIANG Lei;SHENG Jin-chang;LUO Yu-long;ZHAN Mei-li(College of Water Conservancy and Hydropower Engineering,Hohai University,Nanjing,Jiangsu 210098,China)
出处
《岩土力学》
EI
CAS
CSCD
北大核心
2022年第2期405-415,共11页
Rock and Soil Mechanics
基金
国家自然科学基金(No.51579078)
浙江省山体地质灾害防治协同创新中心开放基金(No.PCMGH-2017-Z-02)。
关键词
渗透-应力耦合
孔径分布
压缩敏感性
砂岩
渗透率演化
hydro-mechanical coupling
pore size distribution
compression sensitivity
sandstone
permeability evolution