|Logging-while-coring - new technology from the simultaneous recovery of downhole cores and geophysical measurements|
Goldberg, D.; Myers, G.; Iturrino, G.; Grigar, K.; Pettigrew, T.; Mrozewski, S. (2006). Logging-while-coring - new technology from the simultaneous recovery of downhole cores and geophysical measurements, in: Rothwell, R.G. (Ed.) New techniques in sediment core analysis. Geological Society Special Publication, 267: pp. 219-228
In: Rothwell, R.G. (Ed.) (2006). New techniques in sediment core analysis. Geological Society Special Publication, 267. Geological Society: London, UK. ISBN 1-86239-210-2. 266 pp., more
In: Hartley, A.J. et al. (Ed.) Geological Society Special Publication. Geological Society of London: Oxford; London; Edinburgh; Boston, Mass.; Carlton, Vic.. ISSN 0305-8719, more
|Authors|| || Top |
- Goldberg, D.
- Myers, G.
- Iturrino, G.
- Grigar, K.
- Pettigrew, T.
- Mrozewski, S.
A newly developed logging-while-coring system was deployed during Ocean Drilling Program legs 204 and 209 off the coast of Oregon and near the Mid-Atlantic Ridge. The system consists of two existing devices modified to be used together - a Schlumberger Resistivity-at-the-Bit* tool, and a Texas A&M University wireline-retrieved core barrel and latching tool. The combination allows for precise core-log depth calibration and core orientation within a single borehole, and without a pipe trip. These tests, conducted in clay-bearing sediments (Leg 204) and in crustal peridotite and gabbroic rocks (Leg 209), mark the first simultaneous use of coring and logging-while-drilling technologies. Sediment cores were recovered with 33% recovery, on average, and as high as 68% to 75 m depth below the sea floor. Core recovery in crustal rocks was only 1-2%, however, penetrating to 21 m depth below sea floor, which is attributed to a problem with the core catcher. High-resolution logs were recorded in the downhole tool memory over the entire drilled intervals at both test sites. It is anticipated that logging-while-coring systems will be utilized more routinely where rig time constraints may otherwise preclude coring in difficult drilling environments.