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The Role of Vertical Seismic Profiles in
Core, Log, Seismic Integration
The Role of Vertical Seismic Profiles in
Core, Log, Seismic Integration
Ralph Stephen, WHOICLSI Workshop, Tokyo
October 3-4, 2005
Ralph Stephen, WHOICLSI Workshop, Tokyo
October 3-4, 2005
The first application of borehole seismology on DSDP - the Oblique Seismic Experiment - was to correlate core and logging observations with surface seismic refraction observations of crustal structure.
Head Waves versus Diving Waves (Horizontal Component)
Observed data
Thick layer model of oceanic crust based on head waves.
Gradient layer model of oceanic crust based on diving waves.
Correlation of lithology from cores, resistivity and sonic logging, with offset VSP results from 504B.
Correlation of core-derived lithology with surface seismic reflection data using normal incidence VSP data (Argo Abyssal Plain).
Correlation of Chlorine concentration (salinity), CaCO2 concentration from logging, normal incidence VSP profiles and surface seismic reflection for gas hydrate drilling on the Blake Ridge (ODP Leg 164).
SeisCORK Concept- for time lapse VSPs and offset VSPs- for monitoring micro-earthquake activity
Three basic styles of borehole geophysical measurements: 1) conventional well logging, 2) two-ship borehole experiments (such as offset VSP's that
require the drill ship to be on site) 3) long-term borehole experiments (CORK's, strain installations,
ION broadband seismometers, micro-earthquake monitoring, etc) acquiring data either autonomously or over cable networks (eg ORION).
Scientific Justification for Borehole Seismology
Validating Surface Seismic - Scales of Observation
Validating Surface Seismic - Interference and Multi-path Effects
Extrapolating the Geological Structure Away from the Well
Monitoring Cracking Fronts and Fluid Flow by Micro- and Nano- Earthquake Activity
Monitoring Time-Dependent Effects
Some Typical and Proposed Borehole Seismic Experiments
1) Conventional Well-Logging and Normal Incidence VSP's
2) Two-ship Experiments and Offset VSP's
3) Time-lapse VSP's
4) Long-term Borehole Experiments and "Spin-off"Projects a) Monitoring and locating micro- and nano-earthquakes b) Cross-well tomography c) Broadband Seismometer Installations (ION)