Tsuji Takeshi, Ikeda Tatsunori, Matsuura Ryosuke, Mukumoto Kota, Hutapea Fernando Lawrens, Kimura Tsunehisa, Yamaoka Koshun, Shinohara Masanao
Department of Earth Resources Engineering, Kyushu University, 744 Motooka, Nishi-ku, Fukuoka, 819-0395, Japan.
International Institute for Carbon-Neutral Energy Research (I2CNER), Kyushu University, Fukuoka, Japan.
Sci Rep. 2021 Sep 27;11(1):19120. doi: 10.1038/s41598-021-97881-5.
We have developed a new continuous monitoring system based on small seismic sources and distributed acoustic sensing (DAS). The source system generates continuous waveforms with a wide frequency range. Because the signal timing is accurately controlled, stacking the continuous waveforms enhances the signal-to-noise ratio, allowing the use of a small seismic source to monitor extensive areas (multi-reservoir). Our field experiments demonstrated that the monitoring signal was detected at a distance of ~ 80 km, and temporal variations of the monitoring signal (i.e., seismic velocity) were identified with an error of < 0.01%. Through the monitoring, we identified pore pressure variations due to geothermal operations and rains. When we used seafloor cable for DAS measurements, we identified the monitoring signals at > 10 km far from the source in high-spatial resolution. This study demonstrates that multi-reservoir in an extensive area can be continuously monitored at a relatively low cost by combining our seismic source and DAS.
我们开发了一种基于小型地震源和分布式声学传感（DAS）的新型连续监测系统。该源系统能生成具有宽频率范围的连续波形。由于信号定时得到精确控制，对连续波形进行叠加可提高信噪比，从而能够使用小型地震源来监测广阔区域（多个储层）。我们的现场实验表明，在约80公里的距离处检测到了监测信号，并且监测信号（即地震速度）的时间变化的识别误差小于0.01%。通过监测，我们识别出了地热作业和降雨引起的孔隙压力变化。当我们使用海底电缆进行DAS测量时，在距离源大于10公里处能够以高空间分辨率识别监测信号。这项研究表明，通过结合我们的地震源和DAS，可以以相对较低的成本对广阔区域内的多个储层进行连续监测。
