Mechanisms of hydraulic fracturing induced seismicity

大规模的水力压裂在允许经济地开采北美巨大的致密石油和天然气储量方面已经变得无处不在。微震活动通常伴随着水力裂缝的增长，是在受刺激的储层岩石体积中预先存在的裂缝和断层上的动态滑动的表现。这种滑动可能导致剪切裂缝的扩张，以及储层岩石与水力裂缝（HF）的渗透性和连通性的相关增加，并且因此改善最终产量。在极少数情况下，由水力压裂引起的动态滑动已知会发展成小型到中型地震。这在一些国家禁止压裂的决定中发挥了作用。因此，重要的是要研究由于传播HF引入的应力和孔隙压力扰动而引起的动态和准静态断层滑动的机制，以便能够更好地理解a）它如何影响储层性质和“激发岩石体积”; B）从非地震向动态滑动的转变，以及动态破裂失控（地震）的可能性。

Hydraulic fracturing on a massive scale has become ubiquitous in allowing to economically tap vast tight oil and gas reserves in North America. Microseismicity, which usually accompanies growth of hydraulic fractures, is a manifestation of dynamic slippage on pre-existing fractures and faults in the stimulated reservoir rock volume. This slip may lead to dilation of sheared fractures, and associated increase of permeability and connectivity of the reservoir rock to the hydraulic fracture (HF), and, therefore, improvement to eventual production. On rare occasions, dynamic slip induced by hydraulic fracturing is known to grow out into a small-to-moderate size earthquake. This has played a role in some countries' decision to ban fracturing. It is therefore important to study mechanisms of both dynamic and quasi-static fault slip due to stress and pore pressure perturbations introduced by a propagating HF to be able to better understand a) how it impacts reservoir properties and "stimulated rock volume"; b) the transition from aseismic to dynamic slip, and potential for dynamic rupture run-away (an earthquake).