Standard Wireline Data Processing

IODP logging contractor: USIO/LDEO

Hole: U1354C

Expedition: 317

Location: Canterbury Basin (SW Pacific Ocean)

Latitude: 44 °50.8487' S

Longitude: 171° 47.2080 ' E

Logging date: January 2, 2010

Sea floor depth (driller's): 125 m DRF

Sea floor depth (logger's): 122 m WRF (DIT/DSI/GPIT/HNGS main pass)

Total penetration: 509.2 m DRF (384.2 m DSF)

Total core recovered: 133.37 m ( 42 % of cored section; no coring 0-65 m DSF)

Oldest sediment recovered: late lower Pliocene (4.0-4.3 Ma

Lithologies: mud, sandy mud, muddy sand, marl, sandy marl, clay

Data

The logging data were recorded by Schlumberger in DLIS format. Data were processed at the Borehole Research Group of the Lamont-Doherty Earth Observatory in January 2010.

Logging Runs

Tool string	Pass	Top depth (m WMSF)	Bottom depth (m WMSF)	Pipe depth (m WMSF)	Notes
1. DIT/DSI/GPIT/HNGS	Downlog	0	383	109
	Main	0	383	109	Reference
	Repeat	317	383	Open hole

The hole was drilled to a total depth of 509.2 m DRF (384.2 m DSF) and then conditioned for logging by sweeping with 50 bbl of high viscosity sepiolite/attapulgite mud and displacing with 320 barrels of heavy mud (~ 10.5 ppg). Due to time constraints and hole conditions, a modified triple combo tool string (DIT/DSI/GPIT/HNGS) was used. The HLDS was not run because of concerns about running an eccentralized tool in the same string as a centralized tool (DSI). The wireline heave compensator was used during logging for data collection puroposes, as sea conditions were calm, with peak-to-peak heave of ~ 0.4 m.

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 122 m WRF, which differs 3 m from the driller's sea floor depth (125 m DRF). The sea floor depth was determined by the step in gamma ray values observed on the main pass. The depth-shifted downlog and repeat pass were then depth-matched to the DIT/DSI/GPIT/HNGS main pass (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.

Acoustic data. The dipole shear sonic imager (DSI) was run with the medium frequency monopole, the standard frequency upper dipole and the low frequency lower dipole for downlog, and with the standard frequency monopole (others remain unchanged) for both repeat and main passes. Because of the slow formation, the automatic picking of wave arrivals in the sonic waveforms did not provide consistently reliable results. Reprocessing of all the original waveforms was performed to validate the original data or extract meaningful compressional and shear velocities. The most reliable shear velocity value is the one derived from the lower dipole (VS1), where the lower source frequency used generated more cohert waveforms.

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.

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 317. For further questions about the logs, please contact:

Cristina Broglia

Phone: 845-365-8343

Fax: 845-365-3182

E-mail: Cristina Broglia

Tanzhuo Liu

Phone: 845-365-8630

Fax: 845-365-3182

E-mail: Tanzhuo Liu