Standard Wireline Data Processing

 

 

Science operator: DOSECC/USGS

Logging operator: Schlumberger, Welex

Hole: Cajon Pass Federal 2-26

Location: Cajon Junction, San Bernardino Mountains, California

1144 ft S and 1982 ft E from NW corner of Sec. 26, Twp. 3N, Rge. 6W

Logging dates:

Upper Section: November 11, 1985 (SDT/GR logs), February 11, 1987 (DLL/MSFL/GR), February 12, 1987 (LDT/CNTG/NGT, ACT/GST/NGT), February 14, 1987 (FMS/GPIT/NGT)

Lower section: March 15, 1988 (DLL/MSFL/GR), March 16, 1988 (SDT/GR, LDT/CNT/NGT, ACT/GST/NGT), March 18, 1988 (FMS/GPIT/NGT) April 6, 1988 (Borehole Geometry with Inclinometry)

Elevation (kelly bushing):1009.2 m (3311 ft)

Elevation (ground level): 994.5 m (3279 ft)

Total penetration (phase 1): 2115 m (6939 ft)

Total penetration (phase 2): 3472 m (11393 ft)

Casing: 13 3/8 in at 250.5 m (822 ft)

Casing: 9 5/8 in at 1828.8 m (6000 ft)

Lithologies: sandstone, granodiorite, granite, gneiss.

Sediment/basement contact: 500 m (1640 ft), from GR log.

 

 

Available data

 

The logging data was acquired by Schlumberger in 1987 and 1988. The Schlumberger data was originally available on 9-track magnetic tapes which was susequently transferred to 4 mm-DAT tapes at LDEO-BRG. The dataset available at the time of this review is incomplete, as it does not include any FMS data, resistivity data below 1829 m (the data is corrupted) and acoustic data above 851 m.

The available data were reviewed for quality control and formatted for upload onto the LogDB database at the Borehole Research Group of the Lamont-Doherty Earth Observatory in March 2021.

 

 

Log data Run type Top depth (m) Bottom depth (m) Casing depth (m) Notes
SDT/GR
Upper section Main Pass
850
1826
SDT/GR
Upper section Repeat Pass 4
759
863
SDT/GR
Lower Section Main Pass Interval 1
1825
2072
open hole
SDT/GR
Lower Section Main Pass Interval 2
2065
2180
open hole
SDT/GR
Lower Section Main Pass Interval 3
2161
2714
open hole
SDT/GR
Lower Section Main Pass Interval 4
2658
2792
open hole
SDT/GR
Lower Section Main Pass Interval 5
2788
3422
open hole
SDT/GR
Upper section Repeat Pass 4
759
863
open hole
DLL/MSFL/GR
Upper Section Main Pass
237
1820
250.5
Depth match reference for upper section
LDT/CNT/NGT
Upper Section Main Pass
237
1825
250.5
LDT/CNT/NGT
Lower Section Main Pass
1823
3426
1828.8
Depth match reference for lower section
ACT/GST/NGT
Upper Section Pass 1
242
1821
250.5
ACT/GST/NGT
Upper Section Pass 2
244
1813
250.5
ACT/GST/NGT
Upper Section Pass 3
241
1817
250.5
ACT/GST/NGT
Lower Section
1827
3417
1828.8

 

 

The Cajon Pass 2-26 hole, located 4.3 km from the San Andreas Fault in the San Bernardino Mountains, was drilled in two phases: phase 1 of drilling, coring and logging began in 1986 and ended in 1987, reaching a depth of 2115 m (6939 ft). Phase 2, started in 1987 and completed in 1988, reached a depth of 3472 m (11393 ft). Casing was set at 250.5 (13 3/8 in) and 1828.8 m (9 5/8 in). Logging was carried out by Schlumberger and consisted of acoustic, resistivity, gamma ray, density, porosity,geochemical, and imaging logs. No FMS data is available in digital form; blueprints and plots of the processed images are available at LDEO-BRG.

 

Quality Control

 

The quality of the data is commonly 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 data of hole Cajon Pass 1-26 is of good quality.

 

Gamma ray logs recorded through the casing 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 (LDT, CNT). Hole diameter was recorded by the hydraulic caliper on the LDT tool (CALI) and the FMS tool. No FMS digital data is available. CP-226 caliper data show a very enlarged hole (values > 20 in) to about 730 m. Values range between 10 and 20 in the remainder of the hole, which exhibits frequent washouts.

 

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

 

Additional information about the Cajon Pass project is available at:

 

https://agupubs.onlinelibrary.wiley.com/doi/epdf/10.1029/GL015i009p00945

https://link.springer.com/content/pdf/10.1007%2F978-3-642-73455-7.pdf

https://agupubs.onlinelibrary.wiley.com/doi/toc/10.1002/(ISSN)1944-8007.CAJONPS1

 


Questions about the data available on line can be sent to:

Cristina Broglia

Phone: 845-365-8343

Fax: 845-365-3182

E-mail: Cristina Broglia

 

Gilles Guerin

Phone: 845-365-8671

Fax: 845-365-3182

E-mail: Gilles Guerin