Monitoring changes of the reflection response of the SE2 shear zone due to fluid injection into the KTB pilot borehole by an active seismic reflection experiment

在KTB试验井中，定于2004年4月进行一次广泛的注液试验，将持续约12个月。注水将在约4000米深的井眼裸眼段进行。在该深度处，钻孔与一个主要的地壳剪切带--SE2反射层相交。该建议旨在利用这一独特的机会，通过主动地震反射调查来研究孔压波动和流体流动性对地震信号反射响应的影响。将使用GGA-Institute的P波可控震源产生高度可重复性的地震信号。这些信号将由永久安装的3C地震检波器阵列记录下来。根据注射周期的不同，信号将被重复多次，以监测反射反应的预期变化。对随时间变化的反射反应的分析将是该项目的最后阶段。这些结果将为进一步的结论提供基础，例如评价沿海地壳延时测量的实用性，进一步了解孕震过程的物理过程，或与剪切带内与有效应力有关的弹性性质变化的地震成像研究。

In the KTB pilot borehole an extensive fluid injection experiment is scheduled for April 2004 and will last for about 12 months. The injection will take place in the openhole section of the borehole at a depth of about 4000m. At that depth the borehole intersects a major crustal shear zone, the SE2 reflector. The proposal aims at exploiting this unique opportunity in order to study the influence of pore pressure fluctuations and fluid mobility on the reflection response of seismic signals by means of an active seismic reflection survey. Highly reproducible seismic signals will be generated using the P-wave vibrator of the GGA-Institute. The signals will be recorded by a permanently installed 3C-geophone array. Depending on the injection cycle the signals will be several times repeated in order to monitor the expected variations of the reflecion response. The analysis of the time-dependent reflection responses will be the final stage of the project. The results will provide the basis for further conclusions, like for instance an evaluation of the practicability of conshore crustal time-lapse surveys, a further understanding of the physics of the seismogenic process, or studies relating to the seismic imaging of effective-stress related changes of elastic properties within shear zones.