Wireline Standard Data Processing

ODP logging contractor: LDEO-BRG

Hole: 1189C

Leg: 193

Location: Manus Basin (Bismarck Sea)

Latitude: 3° 43.242' S

Longitude: 151° 40.524' E

Logging date: December 29, 2000

Bottom felt: 1700 mbrf

Total penetration: 166 mbsf

Total core recovered: no recovery (LWD hole)

Logging Runs

Logging string 1: DIT/HLDS/HNGS (2 passes)

Logging string 2: FMS/GPIT/NGT (2 passes)

This hole was drilled and logged with the RAB LWD tools to 166 mbsf. Next, a third party memory temperature tool was sent down the hole, recording a maximum temperature of 40°C; this tool could not pass below 70 mbsf. Subsequent wireline logging of the same hole stopped at the same point. The APS tool was left off the DIT/HLDS/HNGS to speed up the rig-up process and decrease the tool string length.

The wireline heave compensator was used to counter ship heave.

Bottom-hole Assembly

The following bottom-hole assembly depths are as they appear on the logs after differential depth shift (see "Depth shift" section) and depth shift to the sea floor. As such, there might be a discrepancy with the original depths given by the drillers onboard. Possible reasons for depth discrepancies are ship heave, use of wireline heave compensator, and drill string and/or wireline stretch.

DIT/HLDS/HNGS (pass 1 and 2): Bottom-hole assembly at 10 mbsf

FMS/GPIT/NGT (pass 1 and 2): Bottom-hole assembly at 18 mbsf

Processing

Depth shift: The original logs were depth-matched to the GR log from the LWD. The logs were then shifted to the sea floor (-1700 m). The sea floor depth is determined by the step in gamma ray values at the sediment-water interface. It is the same as the "bottom felt" depth given by the drillers (see above).

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 then the features in the equivalent logs from the other runs are matched to it in turn. This matching is performed automatically, and the result checked and adjusted as necessary. 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.

Gamma-ray processing: NGT data have been processed to correct for borehole size and type of drilling fluid. The HNGS data were corrected for hole size during the recording.

DIT data: The SFLU log contains anomalous spikes, due to tool malfunction.

High-resolution data: Bulk density data were recorded at a sampling rate of 2.54 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 is smoothed to match the long-spacing one, 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.

Quality Control

null value=-999.25. This value generally replaces recorded log values or results, which are considered invalid.

Large (>12") and/or irregular borehole affects most recordings, particularly those that require eccentralization (HLDS) and a good contact with the borehole wall. Hole deviation can also affect the data negatively; the FMS, for example, is not designed to be run in holes deviated more than 10 degrees, as the tool weight might cause the caliper to close.

Data recorded through bottom-hole assembly should be used qualitatively only because of the attenuation on the incoming signal.

Hole diameter was recorded by the hydraulic caliper on the HLDS tool (LCAL) and on the FMS string (C1 and C2).

Additional information about the logs can be found in the "Explanatory Notes" and Site Chapter, ODP Leg 193 IR volume. For further questions about the logs, please contact:

Cristina Broglia
Phone: 845-365-8343
Fax: 845-365-3182
E-mail: Cristina Broglia