Data

The logging data were recorded by Schlumberger in DLIS format. Data were processed at the Borehole Research Group of Lamont-Doherty Earth Observatory in March, 2022.

Logging Runs

Tool string	Pass	Top depth (m WMSF)	Bottom depth (m WMSF)	Pipe depth (m WMSF)	Notes
1. VSI/EDTC	Downlog	0	225	76.5	No VSI data

After the completion of coring operations, the VSI/EDTC tool string was first deployed for logging, followed then by the MSS/HNGS/DSI/HLDS/EDTC toolstring. Due to some technical problems encountered during the logging operation, however, only the VSI downlog pass was made to the depth of 225 m WMSF in the open hole; no VSI data were acquired as a result for this hole.

Sea condition was intermediate with ship's heave in the range of 2 to 3 m. The wireline heave compensator (WHC) was not used while logging due to some technical issues.

The depths in the table are for the processed logs (after depth shift to the sea floor). Discrepancies may exist between the sea floor depths determined from the downhole logs and those determined by the drillers from the pipe length. Typical reasons for the depth discrepancies are ship heave, wireline and pipe stretch, tides, and the difficulty of getting an accurate sea floor from a 'bottom felt' depth in soft sediment.

Processing

Depth match and depth shift to sea floor. Since there was only one downlog pass for this hole, no depth match was made for the log.

The original logs were depth-shifted to the sea floor. The sea floor depth was determined by the step in gamma ray values at 4603.0 m WRF observed on the VSI/EDTC downlog. This value differs for 0.4 m from the sea floor depth given by the drillers (see above).

Gamma ray logs recorded through bottom hole assembly (BHA) and drill pipe should be used only qualitatively, because of the attenuation of the incoming signal. The thick-walled BHA attenuates the signal more than the thinner-walled drill pipe.

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 and Downhole Measurements sections of the expedition report, Proceedings of the International Ocean Discovery Program, Expedition 392. For further questions about the logs, if the hole is still under moratorium please contact the staff scientist of the expedition.

After the moratorium period you may direct your questions to:

Tanzhuo Liu

Phone: 845-365-8630

Fax: 845-365-3182

E-mail: Tanzhuo Liu

Gilles Guerin

Phone: 845-365-8671

Fax: 845-365-3182

E-mail: Gilles Guerin