Wireline Standard Data Processing

ODP logging contractor: LDEO-BRG

Hole: 1077A

Leg: 175

Location: Low Congo Basin (tropical SE Atlantic)

Latitude: 5° 10.7969' S

Longitude: 10° 26.1960' E

Logging date: August, 1997

Bottom felt: 2391.5 mbrf

Total penetration: 204.5 mbsf

Total core recovered: 209 m (102.2 %)

Logging Runs

Logging string 1: DIT/SDT/NGT

Wireline heave compensator was used to counter ship heave.

Bottom-hole Assembly

The following bottom-hole assembly depths 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 discrepancies are ship heave and drill string and/or wireline stretch.

DIT/LSS/NGT: Bottom-hole assembly at ~77.5 mbsf.

Processing

Depth shift: Original logs have been depth shifted to the sea floor (- 2388.5 m). This value differs 3 m from the "botom felt" depth given by the drillers.

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

Acoustic data processing: The long spacing sonic was recorded in very homogeneous, unconsolidated sediments; because of the extremely low velocity of the sediments, the computed velocity is less than 1.5 km/s and therefore the velocity profile should be used qualitatively only.

Quality Control

null value=-999.25. This value may replace recorded log values or results which are considered invalid.

During the processing, quality control of the data is generally performed by cross-correlation of all logging data. At Hole 1077A, the interval logged consists of very homogeneous sediments without any characteristic lithologic marker; overall, the logs show a rather uniform character.

Data recorded through bottom-hole assembly, such as the NGT data above 77.5 mbsf, should be used qualitatively only because of the attenuation on the incoming signal.

No hole diameter was recorded at Hole 1077A.

Additional information about the logs can be found in the "Explanatory Notes" and Site Chapter, ODP IR volume 175. For further questions about the logs, please contact:

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