IODP-MSP drilling and logging contractor: ESO
Hole: M0036A
Expedition: 325
Location:
Latitude: 19 40.34388° ' S
Longitude: 150° 14.63781' E
Logging
date:
Sea floor depth (driller's): 103 m DSL
Sea
floor depth (logger's): 122.82 m WRF
Total
core recovered:
8.91 m (26.21 % of cored section)
Lithologies:
The logging data was
recorded by the
Tool string |
Pass |
Top depth (m WMSF)
|
Bottom depth (m WMSF)
|
Pipe depth (m WMSF)
|
Notes |
1. ASGR 512
|
|
|
|
Recorded through pipe |
|
2. DIL45 |
Downlog |
0 |
25.8 |
8 |
|
3. DIL45
|
Uplog |
0 |
25.8 |
8 |
|
4. 2PSA |
Uplog |
7.5 |
|
8 |
|
5. ASGR 256
|
Uplog |
0 |
|
8 |
|
6. EM51 |
Downlog |
0 |
|
8 |
|
7. EM51 |
Uplog |
0 |
7.5 |
8 |
|
8. 2PCA |
Uplog |
- |
- |
8 |
|
Downhole logging was conducted through an Advanced Petroleum Institute (API) hole, the diameter of which is beyond the maximum working size for the acoustic and optical borehole televiewers (ABI40 and OBI40).
The depths in the table are for the processed logs (after applying a depth shift to the sea floor).
Depth
shift: The
original logs were corrected for tool zero (ASGR512: +0.07 m, DIL45: +0.12 m, 2PSA; +0.01 m, ASGR256: +0.08 m, EM51: +0.11 m ) and shifted to the sea floor (-122.82 m). At this hole, each tool was run on an individual string with no repeated measurements between
strings; the open hole (OH) gamma ray log was matched to the gamma ray log measured through pipe, and then the pipe depth kick in all other logs were matched to the pipe kick of the OH gamma log (additional small shifts were made to specific logs: deep conductivity: +0.83 m, medium conductivity: +0.72 m, magnetic susceptibility DL: +0.62 m, magnetic susceptibility UL: +0.65 m, IL DL: +1.05, IL UL: +1.07 m, FWS sonic: -0.09 m). Due
to shallow water and hole depths and maintaining a
fixed zero position at the top of the drill pipe, depth discrepancies between
logs are minimal.
Environmental
corrections: None were applied.
Acoustic data: The 2PSA tool was run at a frequency of 20 kHz . The data was filtered (frequency filter) in such a way that only the energy around the induced frequency (source) was analyzed. Waveform picking was done manually in the LogCrucher software package to ensure good quality data. Time picks were saved and the acoustic velocities were calculated (using the receiver spacing of 1 ft).
The quality
of the data is assessed by checking against reasonable values for the logged lithologies and by correspondence between logs affected by the same formation
property (e.g. the resistivity log should show similar features to the acoustic
log).
A wide and/or irregular borehole affects most recordings, particularly those that require eccentralization and a good contact with the borehole wall. The 2PSA centralizers were undersized, so the tool would fit through the API bit; therefore, the tool was not optimally centralized in the hole and as a result errors were introduced into the measurements.
A null
value of -999.25 may replace invalid log values.
Additional
information about the drilling and logging operations can be found in the
Operations section of the Site Chapter in IODP Proceedings of Expedition 325.
For further questions about the data, please contact:
Dr Louise Anderson
University of
Leicester
Phone:
011-44-116-252-3327
Fax:
011-44--116-252-3918
E-mail: IODP-UK
For any
web site-related problem please contact:
E-mail: Database Manager