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 September 2014.

Logging Runs

Tool string	Pass	Top depth (m WMSF)	Bottom depth (m WMSF)	Pipe depth (m WMSF)	Casing depth (m WMSF)	Notes
1. HRLA/MSS/HLDS/EDTC-B/HNGS	Downlog	0	400	149	177.5	Caliper and HLDS invalid
	Pass 1	208	400	Recorded open hole	Recorded open hole
	Pass 2	0	400	149	177.5	Reference
2. FMS/DSI/GPIT/EDTC-B/HNGS	Downlog	0	400	149	177.5	Caliper and FMS invalid
	Pass 1	190	400	Recorded open hole	Recorded open hole
	Pass 2	0	394	149	177.5

The HRLA/MSS/HLDS/EDTC-B/HNGS was deployed first; it cleared the bottom of the drill pipe and casing without incidents, but it did not pass an obstruction at 3542 m WRF, about 142 m above total depth. After several unsuccessful attempt it was decided to log up from that depth. The second tool string, consisting of the FMS/DSI/GPIT/EDTC-B/HNGS tools also did not pass the obstruction at 3542 m WRF. A downlog and two uplogs were acquired. The wireline heave compensator (WHC) was used throughout the logging operations; due to a tropical storm the sea state was rough with a peak-to-peak heave of ~3 m, particularly during the second tool string deployment.

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 reading 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 (- 3141.5 m). The sea floor depth was determined by the step in gamma ray values at 3141.5 m WRF on the HRLA/MSS/HLDS/EDTC-B/HNGS Pass 2. This differs by 1.5 m from the sea floor depth given by the drillers (see above). The depth-shifted logs have then been depth-matched to the gamma ray log from the second pass of the HRLA/MSS/HLDS/EDTC-B/HNGS tool string.

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, HLDS and HRLA data were corrected for hole size during the recording.

High-resolution data. Bulk density (from the HLDS) data were recorded with a sampling rate of 2.54 cm in addition to the standard sampling rate of 15.24 cm. The enhanced bulk density curve is the result of Schlumberger enhanced processing technique performed on the MAXIS system onboard. While in normal processing short-spacing data are smoothed to match the long-spacing ones, in enhanced processing this is reversed. In a situation where there is good contact between the HLDS pad and the borehole wall (low-density correction) the results are improved, because the short spacing has better vertical resolution. Gamma Ray data from the EDTC-B tool were recorded at sampling rates of 5.08 and 15.24 cm.

Acoustic data. The dipole shear sonic imager (DSI) was operated in the following modes: Upper Dipole in low frequency and P&S Monopole, Stoneley, and Lower Dipole in standard frequency. The sonic velocities were computed from the compressional (DTCO), shear (DT1 and DT2) and Stoneley (DTST) slownesses. Sonic data from the P&S and the lower dipole are generally better than that from the upper dipole and also in agreement with the resistivity data. However, reprocessing of the original sonic waveforms is highly recommended to obtain more reliable velocity results.

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), drill pipe and casing 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 wide (>12") and/or irregular borehole affects most recordings, particularly those that require eccentralization and a good contact with the borehole wall (HLDS). Hole diameter was recorded by the hydraulic caliper on the HLDS tool (LCAL) and by the FMS tool (C1 and C2). The hole is in a slightly irregular shape with most diameter values in the range of 11-1 inches, thus resulting in overall good data.

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 352. 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