Logging-While-Drilling
Data Processing
IODP logging
contractor: CDEX
Hole: C0002G
Expedition: 332
Location: Nankai Trough (NW Pacific Ocean)
Latitude: 33° 18.0126 ' N
Longitude: 136° 38.15' E
Logging-while-drilling date: November 16-20, 2010
Total penetration: 2946 m DRF (980 m DSF)
MWD/LWD data were acquired by Schlumberger Drilling and Measurements. Depth-shifting was performed by CDEX-JAMSTEC logging Services.
The
downhole logs were recorded using the LWD/MWD
(Logging-While-Drilling/Measurement-While-Drilling) system, which employs
instruments that are part of the drill string itself. The advantages of this
technique include being able to log in formations that would not provide a
stable hole for wireline logging (e.g. the upper section of sedimentary
formations) and logging a hole during drilling, so that it is in
good condition and largely free of wash-outs. The data is recorded in the
tool' s memory and downloaded when the drill string returns to the rig floor. A
small subset of the data is transmitted up to the ship during drilling.
Logging Operations Summary
A summary of drilling and logging operations is provided in Table 1. A 12-1/4 in LWD/MWD/BHA string (Figure 1) was initially used to 2858 m DRF, followed by cleaning and sweeping of the hole. This was followed by the 10-/1/2 in LWD/MWD/BHA string, which initially relogged the 2785 m DRF and 2830-2858 m DRF intervals. Drilling resumed at 2858 m DRF to a total depth of 2946 m DRF, followed by a repeat section upward from 2859 to 2830 m DRF.
A composite section consisting of Runs 1, 4 and 5 was produced prior to depth-shifing, which covers the entire hole. All data was depth-shifted to the sea floor (-1966 m DRF).
The data acquired at Hole C0002G are of good quality and allowed for correlation with data acquired during expedition 314 at Hole C0002A.
Additional information about the drilling and logging operations can be found in the Site Chapter of the expedition report, Proceedings of the Integrated Drilling Program, Expedition 332. For further questions about the logs, please contact:
For any question about the propcesing, please contact:
sio7-info@jamstec.go.jp
For any web site-related problem please contact:
E-mail: logdb@ldeo.columbia.edu
