Data

The logging data was recorded by Schlumberger in DLIS format. Data were processed at the Borehole Research Group of the Lamont-Doherty Earth Observatory in October 2009.

Logging Runs

Tool string	Pass	Top depth (m WMSF)	Bottom depth (m WMSF)	Pipe depth (m WMSF)	Notes
1. DIT/HLDS/HNGS	Downlog	0	248	120	Invalid HLDS
	Pass1	103.5	250	120
	Pass 2	0	250	120	Reference
2. FMS/GPIT/HNGS	Downlog	0	222	120	Caliper closed
	Pass 1	148	250	Open hole
	Pass 2	0	250	120

The hole was drilled to a total depth of 3388.4 m DRF and then conditioned for logging by performing a wiper trip and displacing with 56 bbl of barite mud (10.5 ppg). The 9-7/8" RCB bit was released at the bottom of the hole and the pipe was set at 3256.9 m DRF . The logging operations included three passes with the DIT/HLDS/HNGS tool string followed by three passes with the FMS/GPIT/HNGS tool string.

The sea was relatively calm with a peak-to-peak heave of ~ 1.2 m or less. The wireline heave compensator was used during the entire logging operations.

The depths in the table are for the processed logs (after depth shift to the sea floor and depth matching between passes). Generally, 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 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 shift to sea floor and depth match. The original logs were first shifted to the sea floor based on the logger's sea floor depth of 3133 m WRF (step oberved on the GR log at the mudline). This differs 5 m from the driller's sea floor depth (3138 m DRF). The depth-shifted logs were then depth-matched to those of the DIT/HLDS/HNGS pass 2 (reference).

Depth matching is typically done in the following way. One log is chosen as reference (base) log (usually the total gamma ray log from the run with the greatest vertical extent and no sudden changes in cable speed), and then the features in the equivalent logs from the other runs are matched to it in turn. This matching is performed manually. The depth adjustments that were required to bring the match log in line with the base log are then applied to all the other logs from the same tool string.

Environmental corrections. The HNGS and HLDS data were corrected for hole size during the recording.

High-resolution data. Bulk density (HLDS) data were recorded at sampling rates of 2.54 cm in addition to the standard sampling rate of 15.24 cm. Because the short-spaced detector of the HLDS tool did not work properly, the bulk density and photoelectric effect data presented in the database are from the long spacing sensor only. As a consequence, the vertical resolution may not be optimal, since the short-spaced data has better vertical resolution,.

Acoustic data. No acoustic data were acquired.

Quality Control

The quality of the data is assessed by checking against reasonable values for the logged lithologies, by repeatability between different passes of the same tool, and by correspondence between logs affected by the same formation property (e.g. the resistivity log should show similar features to the sonic velocity log).

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.

Hole diameter was recorded by the hydraulic caliper on the HLDS tool (LCAL) and by the FMS tool (C1 and C2). A wide (>12") and/or irregular borehole affects most recordings, particularly those that require eccentralization and a good contact with the borehole wall (HLDS). The caliper logs indicate that the upper part of the borehole (above 185 m WMSF) was washed out to the degree (>14-19") where it may adversely affect the tool response. Thus, density logs in this depth interval should be used with caution.

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 reports, Proceedings of the Integrated Drilling Program, Expedition 324. For further questions about the logs, please contact:

Tanzhuo Liu

Phone: 845-365-8630

Fax: 845-365-3182

E-mail: Tanzhuo Liu

Cristina Broglia

Phone: 845-365-8343

Fax: 845-365-3182

E-mail: Cristina Broglia