Wireline Standard Data Processing

ODP logging contractor: LDEO-BRG
Hole: 1167A
Leg: 188
Location: Prydz Bay (Antarctic Ocean)
Latitude: 66° 24.0108' S
Longitude: 72° 17.0511' E
Logging date: February 27, 2000
Bottom felt: 1651.3 mbrf
Total penetration: 447.5 mbsf
Total core recovered: 191.33 m (42.76%)

Logging Runs

Logging string 1: DIT/APS/HLDS/HNGS + TAP tool

Only limited wireline logging was done at Hole 1167A. The DIT/APS/HLDS/HNGS was stuck for an hour going down through the end of the BHA, and then was blocked at 151 mbsf by a bridge. The interval was logged without opening the HLDS caliper arm. The Wireline Heave Compensator was used to counter ship heave.

At the end of wireline logging, Hole 1167B was logged with the CDR LWD tool.

Bottom-hole Assembly

The following bottom-hole assembly depths are as they appear on the logs after 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, drill string and/or wireline stretch, and tides.

DIT/APS/HLDS/HNGS: Bottom-hole assembly at 85 mbsf

Processing

Depth shift: The original logs were shifted to the sea floor (-1649m). The sea floor depth is determined by the step in gamma ray values at the sediment-water interface. This depth differs by 2.3 m from the driller's sea-floor depth; it corresponds to the mudline as seen on the logs.

Gamma-ray processing: The HNGS data from DIT/HLDS/APS/HNGS were not corrected for hole size during the recording. The low gamma ray values below 111 mbsf are likely due to hole washouts.

High-resolution data: Bulk density and neutron porosity data were recorded at a sampling rate of 2.54 and 5.08 cm respectively. 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.

Quality Control

Null value=-999.25. This value may replace invalid log values or results.

Large (>12") and/or irregular borehole affects most recordings, particularly those that require eccentralization (APS, HLDS) and a good contact with the borehole wall. Though the HLDS caliper was not used in this hole (due to the short interval and concerns about hole stability and the risk of material jamming open the arm), the drops in porosity in the interval 111-131 mbsf indicate a correspondingly wide hole. The caliper arm normally ensures good contact between the HLDS sensors and the borehole wall. Despite the absence of this, the density data from 95-111 mbsf look reasonable.

Additional information about the logs can be found in the "Explanatory Notes" and Site Chapter, ODP IR volume 188. For further questions about the logs, please contact:

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