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)