Wireline Standard Data Processing

ODP logging contractor: LDEO-BRG
Hole: 806B
Leg: 130
Location: Ontong-Java Plateau (tropical NW Pacific Ocean)
Latitude: 0° 19.11' N
Longitude: 159° 21.69' E
Logging date: February, 1990
Bottom felt: 2531 mbrf (used for depth shift to sea floor)
Total penetration: 743.1 mbsf
Total core recovered: 666.4 m (89 %)

Logging Runs

Logging string 1: DIT/SDT/NGT
Logging string 2: ACT/GST/HLDT/NGT (upper and lower sections)
Wireline heave compensator was used to counter ship heave; seas were calm.

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, use of wireline heave compensator, and drill string and/or wireline stretch.
DIT/SDT/NGT: Bottom-hole assembly at ~90 mbsf
ACT/GST/HLDT/NGT: Bottom-hole assembly at 90 mbsf.


Depth shift: Because of the low signature of the NGT logs (< 10 API units) and the uniformity of the lithologies encountered, no depth match between runs is possible. The original logs have been depth shifted to the sea floor (- 2531 m).

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

Acoustic data processing: The array sonic tool was operated in standard depth-derived borehole compensated mode, including long-spacing (8-10-10-12') logs. The sonic logs are of excellent quality and do not need processing; compressional velocity has been computed from the delay times.

Quality Control

null value=-999.25. This may replace invalid recorded log values or results.
During the processing, quality control of the data is mainly performed by cross-correlation of all logging data. Large (>12") and/or irregular borehole affects most recordings, particularly those that require eccentralization (HLDT) and a good contact with the borehole wall.  The HLDT is particularly affected by the large hole in the 290-320 mbsf interval; more low-density readings in the 180-290 mbsf intervals are also he result of poor contact with the borehole wall.
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 hydraulic caliper on the HLDT tool (CALI) by the 3-arm Mechanical Caliper Device (MCD); the HLDT caliper reached its maximum extension (18 inches) above 350 mbsf, thus giving little information about the true conditions of the hole.

Additional information about the logs can be found in the “Explanatory Notes” and Site Chapter, ODP IR volume 130. For further questions, please contact:



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