Transient pulse test and morphological analysis of single rock fractures
Transient pulse test and morphological analysis of single rock fractures
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DOI：
10.1016/j.ijrmms.2016.11.016
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发表时间：
2017
影响因子：
7.2
通讯作者：
Yanlin Zhao;Lianyang Zhang;Weijun Wang;Tan Jingzhou;Hang Lin;W. Wan
中科院分区：
文献类型：
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作者：
Yanlin Zhao;Lianyang Zhang;Weijun Wang;Tan Jingzhou;Hang Lin;W. Wan
在不同围压条件下对单个岩石裂缝进行了瞬态脉冲试验。提出了一种新的基于多项式拟合的数据分析方法来研究流速与水力梯度的关系。采用三维激光扫描定量分析断口在瞬态脉冲试验后或在水-力耦合作用下的形态变化。结果表明：在水力很低时，流速与水力梯度数据梯度呈非线性关系，可能是由于固水相互作用较强，但在水力梯度足够大后，流速与水力梯度数据梯度呈近似线性关系。单个裂缝的渗透率对围压非常敏感。随着围压的增加，当围压低于某一数值时，渗透率首先显著降低，当围压高于某一数值时，渗透率降低的速度要慢得多。随着围压的增大，机械和水力孔径均呈减小趋势。裂缝粗糙度对渗透率的影响与围压大小有关。在低围压条件下，粗裂缝的渗透率较低；但当围压足够高时，情况可能正好相反。当围压超过一定值时，粗糙度不再是影响渗透率的关键因素。
Transient pulse tests were performed on single rock fractures at different confining pressures. A new data analysis method based on polynomial fitting was introduced to investigate the relationship between flow velocity and hydraulic gradient. 3D laser scanning was used to quantify the morphological changes of the fracture surface after the transient pulse test or under the hydro-mechanical coupling effect. The results show that the flow velocity versus hydraulic gradient data gradient shows a nonlinear relationship at very low hydraulic, possibly due to strong solid-water interaction, but becomes approximately linear after the hydraulic gradient is high enough. The permeability of a single fracture is sensitive to the confining pressure. As the confining pressure increases, the permeability first remarkably decreases when the confining pressure is lower than a certain value and then decreases at a much lower speed when the confining pressure is higher than that value. Both mechanical and hydraulic apertures decrease at a decreasing rate with the increase in confining pressure. The effect of fracture roughness on the permeability is related to the magnitude of the confining pressure. Rougher fractures have lower permeability at low confining pressures; but the opposite can be true when the confining pressure is high enough. Roughness is no longer critical to permeability when the confining pressure is over a certain value.