Wireline Standard Data Processing

ODP logging contractor: LDEO-BRG

Well name: 852D

Leg: 138

Location: East Pacific Rise (tropical NE Pacific)

Latitude: 5° 17.550' N

Longitude: 110° 4.537' W

Logging date: June, 1991

Bottom felt: 3871.5 mbrf (used for depth shift to sea floor)

Total penetration: 116 mbsf

Total core recovered: 230.6 m (105.8 %)

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 depth is as it appears 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 and drill string and/or wireline stretch.

ACT/GST/NGT: Bottom-hole assembly at ~ 49.5 mbsf.

Processing

Depth shift: As only one logging run was recorded no depth match between runs was necessary. The original logs have been depth shifted 2.1 m downward to match a carbonate peak from core measurements at 107 mbsf and then to the sea floor (- 3871.5 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 further questions about the logs, please contact:

Cristina Broglia

Phone: 845-365-8343

Fax: 845-365-3182

E-mail: Cristina Broglia