Experimental investigation of the influence of slip velocity and temperature on permeability during and after high-velocity fault slip
Experimental investigation of the influence of slip velocity and temperature on permeability during and after high-velocity fault slip
复制标题
高速断层滑动过程中及滑动后滑动速度和温度对渗透率影响的实验研究
DOI：
10.1016/j.jsg.2011.08.013
复制
发表时间：
2012
影响因子：
3.1
通讯作者：
O. Tadai
中科院分区：
文献类型：
--
作者：
W. Tanikawa;H. Mukoyoshi;O. Tadai
我们使用旋转剪切仪，通过实时测量不同滑动速率的空心砂岩柱体剪切过程中和剪切后的气体流量，研究了断裂带流体运移性质的变化。我们的仪器测量滑动带和围岩中平行于滑动面的渗透率。在所有情况下，渗透率都随着摩擦力的增加而迅速下降，但在滑移后不久就恢复了，并在几十分钟内达到稳定状态。随着滑移速度的增加，渗透率下降的速度增大。渗透率在低速(约0.0019米/S)试验后没有恢复到滑移前的水平，但在高速(约0.29万米/S)试验后恢复到超过滑移前的水平。气体在滑移面的摩擦加热增加了气体的粘度，从而增加了气体的流速，从而产生了明显的渗透率增加。低速试验的不可逆渗透率变化是由于滑动表面的磨损和光滑而形成的断层。高速测试后渗透率的增加是由于温升过快引起的中尺度压裂所致。与剪切变形引起的渗透率变化相比，孔隙流体粘度的变化对流量变化的贡献更大，尽管不同岩石和孔隙流体的测试结果可能有所不同。
We used a rotary shear apparatus to investigate changes of fluid transport properties in a fault zone by real-time measurement of gas flow rates during and after shearing of hollow sandstone cylinders at various slip rates. Our apparatus measures permeability parallel to the slip plane in both the slip zone and wall rocks. In all cases, permeability decreased rapidly with increasing friction, but recovered soon after slip, reaching a steady state within several tens of minutes. The rate of reduction of permeability increased with increasing slip velocity. Permeability did not recover to pre-slip levels after low-velocity (ca. 0.0019 m/s) tests but recovered to exceed them after high-velocity (ca. 0.29 m/s) tests. Frictional heating of gases at the slip surface increased gas viscosity, which increased gas flow rate to produce an apparent permeability increase. The irreversible permeability changes of the low-velocity tests were caused by gouge formation due to wearing and smoothing of the slip surface. The increase of permeability after high-velocity tests was caused by mesoscale fracturing in response to rapid temperature rise. Changes of pore fluid viscosity contributed more to changes of flow rate than did permeability changes caused by shear deformation, although test results from different rocks and pore fluids might be different.