Wireline Standard Data Processing

ODP logging contractor: LDEO-BRG

Well name: 696B

Leg: 113

Location: NW Weddel Sea (Weddel Sea)

Latitude: 61° 50.959' S

Longitude: 42° 55.996' W

Logging date: March, 1987

Bottom felt: 661 mbrf (used for depth shift to sea floor)

Total penetration: 645.6 mbsf

Total core recovered: 156.7 m (27.5 %)

Logging Runs

Logging string 1: DIT/LSS/GR

Wireline heave compensator was 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 depth given by the drillers onboard. Possible reasons for depth discrepancy are ship heave, use of wireline heave compensator, and drill string and/or wireline stretch.

DIT/LSS/GR: Bottom-hole assembly at ~556 mbsf.

Processing

Depth shift: No differential depth shift has been applied, as only one run was recorded. Original logs have been depth shifted to the sea floor (- 661 m).

Acoustic data processing: The long-spacing (8-10-10-12') 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; hole 696B data are generally of good quality. Invalid resistivity and sonic spikes were recorded at 104 mbsf.

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 113. For further questions about the logs, please contact:

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