Next Section | Table of Contents


Logging Plan

Downhole logging will constrain in situ formation properties and is an essential component for achieving Leg 210 scientific objectives. We are planning three logging runs in each of the cored intervals at proposed Site NNB-01A and other sites that may be drilled: (1) triple combo tool string (including the QSST checkshot tool, pending funding), (2) FMS-sonic tool string, and (3) a checkshot with the WST.

The Leg 210 logging plan for proposed Site NNB-01A has been designed to achieve the following objectives:

  1. Core-log-seismic correlation. A detailed correlation between cores, logs, and the extensive suite of high-quality seismic reflection data is critical for understanding the succession of basement and sedimentary rocks and for compiling a detailed sequence stratigraphy. Accordingly, checkshot (WST) surveys, at ~50 m spacing, will be run.
  2. Detailed description of cored sequences and sedimentary features. Integrated interpretation of the FMS and geophysical logs (triple combo) will provide an essential compliment to cores for describing the lithostratigraphy, particularly in intervals where core recovery is incomplete. Fine-scale sedimentary features like bedding, bioturbation, and slumps can be seen on FMS images and this data will help in understanding the paleoenvironment.
  3. Structural analysis of fracture and fault networks by integrating FMS images, log, and core data.

The characteristics of the logging tools are as follows (additional information on these tool strings can be found at

  1. The triple combo tool string includes the Dual Induction Tool (DITE), which measures resistivity from deep and shallow induction, the Accelerator Porosity Sonde (APS), which measures porosity from epithermal neutron measurements, and the Hostile Environment Litho-Density Sonde (HLDS), which measures bulk density from Compton scattering and provides an indication of general lithology from the photoelectric effect. The Hostile Environment Gamma Ray Sonde (HNGS) is added to the top of this tool string.
  2. The FMS-sonic tool string includes the Formation MicroScanner, which measures resistivity at centimeter-scale resolution on four pads moving along the borehole, the General Purpose Inclinometer Tool (GPIT), and the Dipole Sonic Imager (DSI), which measures compressional and shear wave velocity as well as cross-dipole and Stoneley waveforms.
  3. The WST is a checkshot tool used for zero-offset vertical seismic profiles (VSPs). It consists of a single geophone that is used to record acoustic waves generated by a seismic source located near the sea surface. We have also requested use of the QSST tool to obtain a checkshot at total depth when running the triple combo tool string.

Next Section | Table of Contents