论文部分内容阅读
我们确定了两类起源不同与分布不同的相互关联而又独立的微裂隙。一类是在实验室与微裂隙随应力增大而张开产生声发射有关的应力单元所测定的典型的高应力裂隙。另一类是间距密集的应力方向一致的流体饱和的微裂隙。横波分裂监测(SWS)表明微裂隙在上地壳、下地壳,以及地幔最上面400公里处的所有岩石中几乎随处可见。在有些情况下这两种类型的微裂隙可能是相互有关而又相似的(因此定名为“种类”),但通常基本性质是不同的,分布不同,其含义也不同。对油气勘探和开采而言,重要的是,横波分裂监测到了在油气藏层中裂隙的排列和流体流动的优选方向,对天然地震而言,其重要意义是小地震上方横波分裂监测到应力增加对遍布的低应力微裂隙分布的影响,以致于地震之前(地震可能是遥远的)的应力积累可以被识别并对即将发生的地震进行应力预测。
We identified two interrelated and independent microcracks with different origins and distributions. One is the typical high-stress fracture measured in the laboratory with stress cells associated with the development of acoustic emission as the microcracks expand with increasing stress. The other is closely spaced fluid-saturated microcracks with closely spaced stress directions. Shear wave splitting monitoring (SWS) shows that micro-fractures are almost everywhere in the upper crust, the lower crust, and all rocks up to 400 kilometers above the mantle. In some cases, these two types of microcracks may be related to each other and similar (hence the name “species”), but usually the basic properties are different, have different distributions, and have different meanings. For oil and gas exploration and production, it is important that shear-wave splitting monitors the preferred orientation of fractures and fluid flow in the reservoir, which is of importance for natural earthquakes, where stress is detected as a result of shear splitting above the small earthquakes The effect on the distribution of low-stress micro-fractures throughout the earthquake is such that stress buildup prior to the earthquake (the earthquakes may be distant) can be identified and stress predictions of upcoming earthquakes occur.