Standard Data Processing

IODP logging contractor: CDEX-JAMSTEC

Hole: C0010A

Expedition: 319

Location: Nankai Trough (NW Pacific Ocean)

Latitude: 33° 12.5981’ N

Longitude: 136° 41.19249’ E

Logging date: August 6, 2009

Sea floor depth (logger's): 2552 m LRF

Total penetration: 3107 m LRF (555 m LSF)

Total core recovered: None (LWD/MWD used)

Data

MWD/LWD data were acquired by Schlumberger Drilling and Measurements. Depth-shifting was performed by CDEX-JAMSTEC logging Services. Image processing was carried out at the Borehole Research Group of the Lamont-Doherty Earth Observatory in 2011. The data presented online are the result of splicing the data acquired during the two separate main drilling phases and the repeat sections. No information is provided by CDEX-JAMSTEC as to the exact depth of splicing.

Logging Operations Summary

The MWD/LWD assembly used at Hole C0010A includes TeleScope MWD and geoVISION, which measure various drilling parameters, formation resistivity and gamma ray (Table 1 and Figure 1 and 2. Upon making up the MWD/GR assembly, a shallow hole test was made while the ship was drifting to the low cureent area. The drilling assembly entered Hole C0010A through the 20-in conductor pipe for 41 meters and began drilling with an average speed of about 16.5 m/hr. After reaching 3034 m LRF (482 m LSF) drilling operations were suspended to move the ship away from a typhoon's path. After the ship was back on location on August 12, the hole was re-entered and drilling resumed from 3034 m LRF (482 m LSF) with a speed of aboutr 30m/hr, eventually reaching the target depth of 3107 m LRF (555 m LSF). Ship's heave (up to 2.5 m) and stick-slip problems affected the quality of the data, so three repeat sections were logged to improve the data quality: 2790-2870 m LRF (238-318 m LSF), 2846-2858 m LRF (294-306 m LSF) and 2900-2970 m LRF (348-428 m LSF).

Processing

Depth shift to sea floor. All data were depth shifted to the sea floor (-2552 m; see Figure 1).

Environmental corrections. The GR from the geoVISIONtool has been corrected for hole size (bit size), collar size, and type of drilling fluid.

Resistivity data: The geoVISION resistivity is sampled with a 0.03048 m (1.2 in) and 0.1524 m (6 in) sampling rate

Quality Control

Stick slip was experienced almost continuously during logging operations. In addition, high (2.2-2.5 m) heave due to a passing typhoon affected data quality. Logs from the repeat section at 2900-2970 m LRF (348-428 m LSF) show large breakouts relative to phase 1 of drilling. Overall, the quality of the data is fair, with data from phase 1 looking better, due to the reduced effects from reaming the hole. Unlike resistivity, gamma radiation exhibits less variability and changes gradually across the unit boundaries.

This report was prepared at the Borehole Research Group of the Lamont Doherty Earth Oservatory, based on the processing notes and information provided by the logging staff scientists of Expedition 319. Additional information about the drilling and logging operations can be found in the Operations and Downhole Measurements sections of the expedition reports, Proceedings of the Integrated Drilling Program, Expedition 319.

For further information or questions about the processing, please contact

sio7-info@jamstec.go.jp

For any web site-related problem please contact:
E-mail: logdb@ldeo.columbia.edu