Standard Wireline Data

Science operator: University of Puerto Rico, Lamont Doherty Earth Observatory

Logging operator: Halliburton

Hole: Toa Baja 01

Location: Toa Baja (Puerto Rico Northern Coast)

Puerto Rico grid coordinates: X= 171716.2097, Y=66428.5937)

Logging date: November, 1989

Kelly bushing: 32 ft

Ground elevation: 15 ft

Casing depths: 505 ft ( 13.375 in), 2968 ft (9.625 in)

Total penetration (from kelly bushing) : 8872 ft

Cores: 2127-2151 and 3096-3131 ft

Older sediment recovered: Lower Eocene

Lithology: resedimented volcanic material, limestone, and lava flows

Data

The logging data was recorded by Halliburton in LIS format in September (upper section) and November (lower section) 1989. All the data channels were subsequently renamed by Schlumberger using acronyms that were close to the original Halliburton acronyms. The digital data was received from David Larue in January 2021 and reviewed at the Borehole Research Group of the Lamont-Doherty Earth Observatory in February 2021. The dataset included the upper part of the hole (main and repeat) and a merge of the upper and lower sections. The dipmeter was not included. Subsequently, additional data that included the Dipmeter were loaded from 4-mm DAT tapes in DLIS format that were part of the LDEO-BRG archive.

Logging

Geophysical logging in the Toa Baja hole was carried out in two phases: the upper section was logged first from the casing at 505 ft to 2970 ft. After installing another casing at 2968 ft and deepening the hole to the total depth of 8872 ft, the lower part of the hole was logged as well. The logging suite included gamma ray, electrical resistivity (dual induction and laterolog), caliper, spectral density, dual-spaced neutron porosity, long-spacing sonic, spontaneous potential, temperature, and dipmeter. The lower part of the hole (below 2600 ft) was also logged with the Borehole Televiewer (low-frequency tool) and the Halliburton Dipmeter tool. No BHTV was obtained in the upper part, because of poor signal response through the heavy gel mud and the large hole diameter. The BHTV data, which were processed at Stanford University, is not available on the LogDB web site. The logging operations at Toa Baja were completed with a Cement Bond log (CBL) in order to assess the quality of the cementing job. Only an analog blueprint of the CBL is available at LDEO, as well as a complete set of the original blueprints for all other logs.

Summary of the Halliburton logging runs:

DIL/LL3/LSS/GR

SDT/DSN/SP/GR

DIPMETER/GR

CBL/GR

The following tools are available in digital form: DIL/LL3/LSS/SP/GR/SLD/DSN/TEMP/DIPMETER.

Processing

Depth match. The original logs were compared using the gamma ray log to evaluate any possible mismatch. Only the DIPMETER logs needed to be depth-matched. The logs were depth-matched to the spliced gamma ray log from the main pass of the DIL/LSS/GR tool string. Depth matching was done by comparing features on the gamma ray curve. The depth adjustments that were required to bring the match log in line with the base log are then applied to all the other logs from the same tool string.

Acoustic data. Velocity was computed from the long spacing sonic delay times DT and DTL. The data is generally of good quality. A synthetic seismogram was generated at LDEO in 1989 and the resulting figure is available on the web site.

Quality Control

The quality of the data is assessed by checking against reasonable values for the logged lithologies, by repeatability between different passes of the same tool, and by correspondence between logs affected by the same formation property (e.g. the resistivity log should show similar features to the sonic velocity log). The logs of the Toa Baja hole are of very good quality.

The gamma ray logs was recorded open hole and through casing above 505 ft. The data acquired in the cased section should be used only qualitatively, because of the attenuation of the incoming signal.

A wide and/or irregular borehole affects most recordings, particularly those that require eccentralization and a good contact with the borehole wall (SLD, DSN). Hole diameter was recorded by the hydraulic caliper on the SLD (CALI) and Dipmeter (C1, C2) tools. The data shows a generally good hole, with a few local washouts.

A null value of -999.25 may replace invalid log values.

Additional information about the Toa Baja Project can be found at https://doi.org/10.1029/91GL00406 and https://doi.org/10.1029/91GL00405

For further questions about the logging data please contact:

Cristina Broglia

Phone: 845-365-8343

Fax: 845-365-3182

E-mail: Cristina Broglia