Wireline Standard Data Processing

ODP logging contractor: LDEO-BRG

Well name: 661A

Leg: 108

Location: Sierra Leone Rise (tropical NE Atlantic)

Latitude: 9° 26.81' N

Longitude: 19° 23.166' W

Logging date: March, 1986

Bottom felt: 4023.2 mbrf (used for depth shift to sea floor)

Total penetration: 296.1 mbsf

Total core recovered: 235.1 m (79.3 %)

Logging Runs

Logging string 1: DIT/LSS/GR

An attempt to run the LDT/CNTG/NGT logging string failed.

         No information available about use of wireline heave compensator 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 and drill string and/or wireline stretch.

         DIT/LSS/GR: Bottom-hole assembly at ~70 mbsf.

Processing

         Depth shift: Original logs have been depth shifted to the sea floor (- 4023.2 m).

         Acoustic data processing: The long spacing sonic data were of good quality and did not need further processing.

 

Quality Control

         During the processing, quality control of the data is mainly performed by cross-correlation of all logging data. Log data at hole 661A are of good quality.

         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 3-arm mechanical caliper device (MCD).

         Additional information about the logs can be found in the "Explanatory Notes" and Site Chapter, ODP IR volume 108.

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