Wireline Standard Data Processing

ODP logging contractor: LDEO-BRG

Well name: 504B

Leg: 111

Location: Costa Rica Rift (tropical NE Pacific)

Latitude: 1°13.611' N

Longitude: 83°43.818' W

Logging date: September, 1986

Bottom felt: 3474 mbrf (used for depth shift to sea floor)

Total penetration: 1562.3 mbsf

Total core recovered: 26.4 m (12.6 %)

Logging Runs

Logging string 1: Multichannel Sonic (MCS)

Logging string 2: ACT/GST/NGT (before coring operations)

Logging string 3: ACT/GST/NGT (after coring operations)

Logging string 4: DLL

Logging string 5: LDT/CNTG/NGT

Logging string 6: WST

No information available in the shipboard logging report about use of wireline heave compensator to counter ship.

Casing

The casing was set at 274.5 mbsf. The ACT/GST/NGT data recorded before coring were collected through casing.

Processing

Depth shift: Because the gamma ray log had not been recorded on all of the logging runs and due to its low signature, it has not been possible to depth match the different runs. Cross-correlation of all the logs, however, did not reveal any major depth inconsistency. The DLL has been used as a depth reference for Legs 140 and 148 during which Hole 504B was re-entered, deepened, and logged. The logs have been depth shifted to the sea floor (- 3474 m).

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

Acoustic data processing: The acoustic data collected with the Multichannel Sonic Tools were processed at LDEO-BRG; the results include compressional and shear velocities, semblance, and velocity ratio. This data is not included in the on-line database but can be requested to LDEO-BRG.

Porosity data: Different porosity estimates have been obtained from the Dual Laterolog porosity measurements: they include total, primary and fracture porosity, and horizontal and fracture porosity. This data is not included in the on-line database but can be requested to LDEO-BRG.

Geochemical processing: Hole 504B was logged with the geochemical tool during this leg and again during Leg 140; a modified boron sleeve (absent during Leg 111), was introduced during Leg 126. The sleeve helps to reduce the effect of the steel within the tool itself on the iron yield, thus eliminating the need to correct the data. It also contributes to improve the overall response of the geochemical tool. Because of the higher quality of the geochemical data collected during Leg 140, and of some general improvements applied to the processing routines, we refer to Leg 140 for a geochemical profile of Hole 504B. Therefore, Leg 111 geochemical data is not included in the database.

Quality Control

null value=-999.25. This 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. Large (>12") and/or irregular borehole affects most recordings, particularly those that require eccentralization (CNTG, LDT) and a good contact with the borehole wall.

Data recorded through bottom-hole assembly should be used qualitatively only because of the attenuation on the incoming signal.

No hole diameter was measured during Leg 111. A caliper measurement computed from Borehole Televiewer data collected during a DSDP leg is not included in the on-line database but is available upon request.

Additional information about the logs can be found in the "Explanatory Notes" and Site Chapter, ODP IR volume 111. For further questions about the logs, please contact:

Cristina Broglia

Phone: 845-365-8343

Fax: 845-365-3182

E-mail: Cristina Broglia