High‐Resolution Ambient Noise Imaging of Geothermal Reservoir Using 3C Dense Seismic Nodal Array and Ultra‐Short Observation
High‐Resolution Ambient Noise Imaging of Geothermal Reservoir Using 3C Dense Seismic Nodal Array and Ultra‐Short Observation
复制标题
DOI：
10.1029/2021jb021827
复制
发表时间：
2021-08
期刊：
影响因子：
--
通讯作者：
F. Cheng;J. Xia;J. Ajo-Franklin;M. Behm;Changjiang Zhou;Tianyu Dai;Chaoqiang Xi;J. Pang;Changwei Zhou
中科院分区：
文献类型：
--
作者：
F. Cheng;J. Xia;J. Ajo-Franklin;M. Behm;Changjiang Zhou;Tianyu Dai;Chaoqiang Xi;J. Pang;Changwei Zhou
基于长期环境地震噪声测量的层析成像，主要是来自表面波的相位信息，已被证明是地热储层成像和监测的有力工具。在这项研究中，我们利用来自密集节点阵列（20平方公里内192个3C节点）的地震噪声数据，在超短的观测周期（4.7天）内重建了表面波，并确定了中国浙江农村城镇地下高分辨率（0.2公里）三维（3 - D） S波速结构。我们报告了在抑制由持续源引起的伪到达方面，交叉相干优于相互相关。我们使用环境噪声干涉测量法来检索高质量的瑞利波和洛夫波。在R - R分量干涉图上也观察到体波。我们在瑞利波和洛夫波上应用相速度色散测量，并通过使用机器学习技术自动选择23,000多条色散曲线。深度反演后的三维面波层析成像结果表明，在中部地区，从地表到2公里深度的低速异常（在- 1%到- 4%之间）。结合电阻率剖面上观察到的导电特征，推断该低速异常为高断裂岩石的流体饱和带。基于水平-垂直光谱比（HVSR）测量和附近一口井现有的温度和流体电阻率记录的联合解释表明，在裂缝通道中存在高温地热田。HVSR测量值与S波速度模型之间的强相关性突出了从环境噪声中提取振幅和相位信息的潜力。
Tomographic imaging based on long‐term ambient seismic noise measurements, mainly the phase information from surface waves, has been shown to be a powerful tool for geothermal reservoir imaging and monitoring. In this study, we utilize seismic noise data from a dense nodal array (192 3C nodes within 20 km2 ) over a ultra‐short observation period (4.7 days) to reconstruct surface waves and determine the high‐resolution (0.2 km) three‐dimensional (3‐D) S wave velocity structure beneath a rural town in Zhejiang, China. We report the advantage of cross‐coherence over cross‐correlation in suppressing pseudo‐arrivals caused by persistent sources. We use ambient noise interferometry to retrieve high quality Rayleigh waves and Love waves. Body waves are also observed on the R‐R component interferograms. We apply phase velocity dispersion measurements on both Rayleigh waves and Love waves and automatically pick more than 23,000 dispersion curves by using a Machine Learning technique. 3‐D surface wave tomographic results after depth inversion indicate low‐velocity anomalies (between −1% and −4%) from the surface to 2 km depth in the central area. Combined with the conductive characteristics observed on resistivity profile, the low‐velocity anomalies are inferred to be a fluid saturated zone of highly fractured rock. Joint interpretation based on horizontal‐to‐vertical spectral ratio (HVSR) measurements, and existing temperature and fluid resistivity records observed in a nearby well, suggests the existence of the high‐temperature geothermal field through the fracture channel. Strong correlation between HVSR measurements and the S wave velocity model highlights the potential of extraction of both amplitude and phase information from ambient noise.