Standard Wireline Data Processing
Science operator: JAPEX-JNOC-GSC
Hole: Mallik-5L38
Location: McKenzie Delta, Northwest Territories, Canada
Latitude: 69° 27' 39.302" N
Longitude: 134° 39' 38.898" W
Logging date: February 21-22, 2002
Total penetration: 1166 m
Permafrost depth: 613 m
Casing depth: 676.5 m
Kelly bushing: 5.6 m
above sea level. Depth reference for all logs.
Ground elevation: 1 m
above sea level.
Gas hydrate zones: 892-930 (A), 9342-993 m (B), 1070-1107 m (C)
Lithologies: Sand, silty sand, and sandy silt with various amounts of clay.
The logging data was recorded by Schlumberger in DLIS format. Data were processed at the Borehole Research Group of the Lamont-Doherty Earth Observatory in October 2020.
| Tool string | Pass
|
Top (m) |
Notes | ||
1. HRLA/MCFL/TLD/HGNS (Platform Express) |
|
open hole |
Permafrost interval. |
||
2. AIT/MCFL/HRLA/TLD/HGNS/SP (Platform Express) |
|
676.5 |
Depth reference run. |
||
open hole |
|||||
3. FMI/SGT
|
676.5 |
||||
open hole |
|||||
4. CMR/HGNS/SGT
|
|
open hole
|
3 additional dlis files available for CMR stations |
||
open hole |
|||||
5. DSI/GPIT/HNGS
|
676.5 |
||||
open hole |
|||||
6. RST/GR |
open hole |
8 original files (DLIS) included in database |
|||
7. CHFR |
cased hole |
œ |
Mallik-5L38 was drilled and logged in 2002. The open-hole logging program consisted of severallogging strings, with the first one acquiring data in the permafrost zone before the installation of the casing at 676.5 m. The RST (Reservoir Saturation Tool) tool string completed the open-hole program. After the lower part of the hole was cased, it was logged with a Cased Hole Formation Resistivity Tool (CHFR), a gyroscopic directional survey, several time-series runs of the RST, and a borehole survey with the Casing Bond tool (CBT; only the CHFR is included in the LogDB database).
Depth match. The original logs were depth-matched to the gamma ray log from the main main pass of the AIT/MCFL/HRLA/TLD/HGNS/SP tool string. Depth matching was done by comparing features on the gamma ray curve from the different runs. 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. The datasets required only minimal depth adjustments.
The processed DSI data were loaded from the available DVD included in the Scientific Results of Mallik-5L38. The data was originally in LAS format and has been depth-matched to the depth-matched original DSI data. The resistivity data recorded through casing (CHFR) have an irregular sampling rate and as such could not be depth matched to the reference run.
All logs depths are referred to the kelly bushing, which is 5.6 m above sea level.
Environmental
corrections. None applied to the resistivity and gamma ray logs.
Sampling rates:
- acoustic data: 1524 cm (DSI)
- caliper data: 15.24 cm (FMI, DSI), 2.54 cm (PEX), 5.08 cm (CMR)
- density data: 2.54 cm
- gamma ray: 15.24 cm and 5.08 cm
- general purpose inclinometer: 15.24 cm
- nuclear magnetic resonance: 15.24 cm
- porosity: 5.08 cm (HGNS)
- resistivity data: 15.24 cm, 7.62 cm (AIT), 5.08 cm (HRLA and MCFL), uneven sampling rate (CHFR, casing)
- spontaneous potential: 15.24 cm
Acoustic data. The dipole shear sonic imager (DSI) was operated in the following modes: P&S monopole, upper and lower dipole, Stoneley, and cross-dipole (main and repat pass). The velocities were computed from the delay times. They are generally of very good quality.
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 data at the Mallik hole is of excellent quality.
Gamma ray logs
recorded through the casing should be used only
qualitatively, because of the attenuation of the incoming signal.
Hole diameter was recorded by the hydraulic caliper on the TLD (HCAL) and CMR tools (HD1, HD2, HD3) and by the FMI tool (C1 and C2).
A null value of
-999.25 may replace invalid log values.
Additional information about the drilling and logging operations can be found in the Geological Survey of Canada Bulletin 585 (https://doi.org/10.4095/220702).
For questions about the logDB database, you may direct your questions to:
Cristina Broglia
Phone: 845-365-8343
Fax: 845-365-3182
E-mail: Cristina Broglia
Tanzhuo Liu
Phone: 845-365-8630
Fax: 845-365-3182
E-mail: Tanzhuo Liu
Gilles Guerin
Phone: 845-365-8671
Fax: 845-365-3182
E-mail: Gilles Guerin