Logging-While-Drilling Data Processing

Coring and logging operator: CDEX

Hole: C0019B

Expedition: 343

Location: Japan Trench (NW Pacific Ocean)

Latitude: 37° 56.3367' N

Longitude: 143° 54.8100' E

Logging-while-drilling date: April 21-25, 2012

Sea floor depth (as seen on logs): 6918 m LRF

Total penetration: 7768.5 m LRF (850.5 m LSF)



Logging Tools


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 immediately 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.


The following services were employed in Hole C0019B :

geoVISION-8 / arcVISION-8 (resistivity, resistivity images, velocity and gamma ray, azimuth, annulus fluid temperature and pressure)


The rate of penetration ranges from 10 to about 75 m/hr.






Depth shift: The original logs have been depth shifted to the sea floor (- 6918 m) by JAMSTEC personnel.

Gamma Ray data processing: Gamma Ray data is measured as Natural Gamma Ray (GR): according to the header of the printouts produced by Schlumberger, the GR has been corrected for bit and tool size and mud weight. There was no potassium in the mud.


Resistivity data: The geoVISION resistivity is sampled with a 0.03048 m (1.2 in) sampling rate. According to the header of the printouts produced by Schlumberger, the resisistivity has been corrected for bit size and mud resistivity.





Quality Control


During the processing, quality control of the data is performed by inter-comparison of all logging data to ensure that reasonable values are returned for expected lithology types and features on the logs reflect true formation characteristics and are not artifacts. The overall quality of the logging data is good.


Additional information about the drilling and logging operations can be found in the Operations and Logging-while-drilling sections of the expedition report, Proceedings of the Integrated Drilling Program, Expedition 343.


For questions about the online database, please contact:


Cristina Broglia

Phone: 845-365-8343

Fax: 845-365-3182

E-mail: Cristina Broglia


For questions about the procesing of the resistivity images, please contact:


Tanzhuo Liu
Phone: 845-365-8630
Fax: 845-365-3182
E-mail: Tanzhuo Liu


For questions about the logs, please contact:


Yoshinori Sanada

E-mail: sanada@jamstec.go.jp


Yukari Kido

E-mail: ykido@jamstec.go.jp


Saneatsu Saito

E-mail: saito@jamstec.go.jp