Wireline Standard Data Processing

ODP logging contractor: LDEO-BRG

Well name: 703A

Leg: 114

Location: Meteor Rise (central S Atlantic)

Latitude: 47° 03.042' S

Longitude: 7° 53.679' E

Logging date: April, 1987

Bottom felt: 1806.6 mbrf (used for depth shift to sea floor)

Total penetration: 377.4 mbsf

Total core recovered: 192.3 m (50 %)

Logging Runs

Logging string 1: DIT/BHC/GR

No wireline heave compensator was used due to mechanical failure; ship's heave was about 5 m.

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/BHC/GR: Bottom-hole assembly at ~61.5 mbsf.

Processing

Depth shift: No shift necessary because only one run was recorded. The data was depth shifted to the sea floor on board the ship, but the amount is not indicated in the header of the blueprints. It is suspected, however, that it was shifted the water depth amount and not the drillers' "bottom felt depth". For this reason, an additional shift of 10.5 m upward has been applied.

Acoustic data processing: The borehole compensated sonic logs have been processed to eliminate some of the noise and cycle skipping experienced during the recording. Using two sets of the four transit time measurements and proper depth justification, four independent measurements over a -2ft interval centered on the depth of interest are determined, each based on the difference between a pair of transmitters and receivers. The program discards any transit time that is negative or falls outside a range of meaningful values selected by the processor.

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 (ex. processed sonic data).

During the processing, quality control of the data is mainly performed by cross-correlation of all logging data. The data is generally 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 114. For further questions about the logs, please contact:

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