Standard Wireline Data Processing
Science operator: Texas A&M University
Hole: U1602E
Expedition: 395
Location: Reykjanes Mid-Ocean Ridge, North Atlantic
Latitude: 61° 11.7150' N
Longitude: 38° 10.7961' W
Logging date: July 22, 2023
Sea floor depth (driller's): 2720.7 m DRF
Sea floor depth (logger's): 2720.7 m WRF
Total penetration: 4085.9 m DRF (1365.2 m DSF)
Total core recovered: 450.39 m (53.9 % of cored section)
Oldest sediment recovered:
Lithology: Sandstone, siltstone, silty claystone with layers of sand and nanofossil chalk
The logging data were recorded by Schlumberger in DLIS format. Data were processed at the Borehole Research Group of Lamont-Doherty Earth Observatory in July 2023.
| Tool string | Pass
|
Top depth (m WMSF) | Bottom depth (m WMSF) | Pipe depth (m WMSF) | Notes |
MSS/HRLA/HLDS/APS/HNGS/EDTC-B
|
|
76 |
Caliper closed. Invalid APS and HLDS. |
After the completion of coring operations, a triple combo tool string of MSS/HRLA/HLDS/APS/HNGS/EDTC-B was deployed for logging. The downlog was collected from below sea floor to a depth of 1277.8 m WMSF without any incident. At 1277.8 m WMSF, the tool string became stuck and the tool fishing operation was initiated. As a result, the subsequent logging operations with the triple combo and FMS/DSI tool strings were cancelled.
The Wireline Heave Compensator (WHC) was used in the open hole interval to counter the ship heave while logging down. Sea condition was low with peak-to-peak heave in the 0.5 m range.
Depth matching and depth shift to sea floor. Since only one downlog was collected for Hole U1602E, no depth matching was needed and the downlog was directly depth-shifted to the sea floor at 2720.7 mbrf determined by the driller.
Environmental corrections. The HRLA log was corrected for hole size during the recording.
High-resolution data. The HRLA data were acquired every 5.08 cm; in the database they were resampled at 15.24 cm, for ease of comparison with the other logs.
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 susceptibility log).
Gamma ray logs
recorded through bottom hole assembly (BHA) and drill pipe should be used only
qualitatively, because of the attenuation of the incoming signal. The
thick-walled BHA attenuates the signal more than the thinner-walled drill pipe.
A wide (>12") and/or irregular borehole affects most recordings, particularly those that require eccentralization and a good contact with the borehole wall (HLDS). For Hole U1602E, no caliper data were collected during the logging operation and the borehole condition was thus difficult to evaluate.
A null value of
-999.25 may replace invalid log values.
Additional information about the drilling and logging operations can be found in the Operations and Downhole Measurements sections of the expedition report, Proceedings of the International Ocean Discovery Program, Expedition 395. For further questions about the logs, if the hole is still under moratorium please contact the staff scientist of the expedition.
After the moratorium period you may direct your questions to:
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