A vertical seismic profiling (VSP) survey conducted in 2010 in the original RRG-9 well at the Raft River geothermal field is to understand the subsurface geologic structures for geothermal reservoir characterization. This survey consists of 40 three-component (3C) geophones deployed in the upper 600 m of the well and 255 vibroseis sources positioned along eight walkaway lines at the surface. We perform elastic-waveform inversion and reserve-time migration of the VSP data to obtain high-resolution subsurface images. We first process the raw walkaway 3C VSP data and separate the upgoing compressional-to-compressional (PP) and compressional-to-shear (PS) wavefields. We then build an initial velocity model based on sonic logging and zero-offset VSP data, update the initial model with first-arrival traveltime tomography, and refine the model using elastic-waveform inversion to reveal high-resolution velocity variations. We finally apply reverse-time migration to the upgoing wavefields to obtain high-resolution PP and PS migration images of the lithologies encountered in the well. The refined velocity models obtained using elastic-waveform inversion improve the subsurface migration imaging results. Our elastic-waveform inversion and reverse-time migration confirm the lithology interfaces revealed from well logs and provide images of subsurface geologic layers away from well RRG-9 at the Raft River geothermal field.

2010年在筏河地热田的原始RRG-9井中进行了垂直地震剖面（VSP）调查，目的是了解地下地质结构，以进行地热储层表征。该调查由40口三分量（3C）地震检波器组成，这些检波器部署在井的上部600 m中，而255个振动源沿地面的八条走动线布置。我们执行VSP数据的弹性波形反演和保留时间偏移，以获得高分辨率的地下图像。我们首先处理未经处理的3C VSP原始数据，并分离上行的压缩至压缩（PP）和压缩至剪切（PS）波场。然后，我们基于声波测井和零偏移VSP数据建立初始速度模型，并使用首次到达的行进时间层析成像技术更新初始模型，并使用弹性波形反演改进模型，以揭示高分辨率速度变化。最后，我们将逆时偏移应用于上行波场，以获得井中遇到的岩性的高分辨率PP和PS偏移图像。使用弹性波形反演获得的精确速度模型改善了地下迁移成像结果。我们的弹性波形反演和逆时偏移证实了测井记录所揭示的岩性界面，并提供了在Raft River地热场中远离RRG-9井的地下地质层的图像。使用弹性波形反演获得的精确速度模型改善了地下迁移成像结果。我们的弹性波形反演和逆时偏移证实了测井记录所揭示的岩性界面，并提供了在Raft River地热场中远离RRG-9井的地下地质层的图像。使用弹性波形反演获得的精确速度模型改善了地下迁移成像结果。我们的弹性波形反演和逆时偏移证实了测井记录所揭示的岩性界面，并提供了在Raft River地热场中远离RRG-9井的地下地质层的图像。