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地震过程中相当可观的一部分能量消耗于裂隙的活化与形成,来自汶川地震断裂带科学钻探一号孔(WFSD-1)的随钻流体表明,地震新形成的裂隙对应有较强的流体异常,它们为流体的入侵提供了良好的通道。随钻流体呈非对称性分布于主滑移面的两侧,主要的流体异常带集中在主滑移带下方须家河组顶部120 m范围内,该带中气体的含量以及变动的频率明显高于上部相同的宽度范围以及下部沉积岩层,来自地球物理测井的资料同样显示这一带破碎严重并伴随有大量水的侵入,暗示汶川地震形成的裂隙具有非对称性分布的特征。这一特征可能同时受控于断裂上盘彭灌杂岩与下盘须家河组岩层的力学性质差异以及地震破裂过程中形成的非对称性应力分布。
A considerable part of the energy during the earthquake is consumed in the activation and formation of fractures. The WDM drilling fluid from the WFSD-1 Wenchuan earthquake fault zone indicates that the newly formed fractures of the earthquake corresponded to strong fluid anomalies, They provide a good channel for fluid intrusion. The asymmetry of the fluid along the borehole distributes on both sides of the main slip surface. The major fluid anomalies are concentrated within 120 m of the top of the Xujiahe Formation below the main slip zone, and the gas content and the frequency of fluctuations in this zone are obvious Data from geophysical well logs above the same width of the upper and lower sedimentary formations also show that the belt is severely fractured and accompanied by large amounts of water intrusion, suggesting that fractures formed by the Wenchuan earthquake have asymmetric distributions. This feature may be controlled by both the difference in mechanical properties between the fractured supracrustal and the Xujiahe formation and the asymmetric stress distribution formed during the earthquake rupture.