Wireline Standard Data Processing

ODP logging contractor: LDEO-BRG

Hole: 848B

Leg: 138

Location: East Pacific Rise (tropical NE Pacific)

Latitude: 2° 59.634' N

Longitude: 110° 28.791' W

Logging date: June, 1991

Bottom felt: 3867.3 mbrf

Total penetration: 93.8 mbsf

Total core recovered: 97.8 m (104.2 %)

Logging Runs

Logging string 1: ACT/GST/NGT

Wireline heave compensator was not 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.

     

ACT/GST/NGT: Bottom-hole assembly at ~86 mbsf.

Processing

Depth shift: No differential depth shift was necessary as only one logging pass was recorded. Original logs have been interactively depth shifted  to the sea floor (- 3867.2 m).

Gamma-ray processing: NGT data have been processed to correct for borehole size and type of drilling fluid.

Quality Control

Null value=-999.25. This value generally appears in discrete core measurement files and also it may replace recorded log values or results which are considered invalid.

     

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

Additional information about the logs can be found in the "Explanatory Notes" and Site Chapter, ODP IR volume 138.

For any question about the data or about the LogDB database, please contact LogDB support: logdb@ldeo.columbia.edu.