[M-GI31] Drilling Earth Science

[MGI31-05] Monitoring and Modeling of Pore Pressure and Hydraulic Parameters Using Borehole and Geophysical Data

★Invited Papers

*Takeshi Tsuji¹ (1.Graduate School of Engineering, the University of Tokyo)

Keywords:Pore pressure, Monitoring, Modeling, Slow earthquake, Digital rock physics

Pore pressure plays significant role in numerous earth processes such as seismic activity, volcanic phenomena, and landslides. It should be further considered in energy resource and carbon-neutral projects like CCS. Borehole data serves as a reliable source for acquiring precise information on pore pressure and hydraulic parameters. Here we showed the study of pore pressure or stress state estimation in the Nankai subduction zone based on the drilling and geophysical data. The comprehensive analysis allows us to characterize pore pressure conditions in both slow- and fast-earthquake regions along the plate boundary fault. Furthermore, the integration of seismic and drilling data has enabled the interpretation of the role of tectonic backstop that could influence earthquake magnitudes.
The temporal variation of pore pressure or stress state can be also identified by recent monitoring technology. To assess dynamic pore pressure behaviors, we have developed a monitoring system utilizing ambient noise. The monitoring system has been applied to identify changes of pore pressure related to earthquakes and volcanic activities at a high temporal resolution (~1 day). To further enhance spatial resolution for monitoring localized events, we have developed a continuous seismic source that can be installed in boreholes. In this presentation, we also show the results derived from such new monitoring and modeling technologies.