Calculable fluid–rock interactions
Calculable fluid–rock interactions
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DOI：
10.1144/gsjgs.156.3.0501
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发表时间：
1999-05
影响因子：
2.7
通讯作者：
S. Crampin
中科院分区：
文献类型：
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作者：
S. Crampin
本文介绍了一种岩石变形模型（各向异性孔隙弹性或 APE），可以计算流体饱和岩石在压裂之前对变化条件的响应。变形的驱动机制是流体沿相邻晶间微裂纹和应力场不同方向的孔隙之间的压力梯度迁移。控制微裂纹几何形状变化的参数也控制地震剪切波的分裂（双折射），因此可以通过分析几乎所有岩石中观察到的剪切波分裂来直接监测变形的变化。对地壳中剪切波分裂和 APE 模型的分析表明，地壳中大部分为粒间裂缝的分布在几何上总是接近于断裂，这意味着剪切波分裂对相对较小的应力变化和原位条件的较小变化很敏感。这对岩体的临界状态具有重要意义，因此，在较大地震之前，在适当的源-接收器几何形状与适当的地震活动一致的少数情况下，观察到了剪切波分裂的变化。 APE 对于监测碳氢化合物采收期间储层条件的变化也具有重要意义。
This paper introduces a model of rock deformation (anisotropic poro-elasticity or APE), where the response of fluid-saturated rock to changing conditions, prior to fracturing, can be calculated. The driving mechanism for deformation is fluid migration along pressure gradients between neighbouring intergranular microcracks and pores at different orientations to the stress field. The parameters that control changes to microcrack geometry also control the splitting (birefringence) of seismic shear-waves, so that changes in deformation can be directly monitored by analysing the shear-wave splitting which is observed in almost all rocks. Analysis of shear-wave splitting in the Earth's crust and APE-modelling show that distributions of, mostly intergranular, cracks in the crust are always geometrically close to fracturing with the implication that shear-wave splitting is sensitive to comparatively minor changes of stress and minor changes of in situ conditions. This has important implications for the state of criticality of the rockmass and, as a consequence, changes in shear-wave splitting have been observed before larger earthquakes on those few occasions when suitable source–receiver geometry coincides with appropriate seismic activity. APE also has implications for monitoring changing conditions in reservoirs during hydrocarbon recovery.