Sonic Waveform Data
Science operator: Texas A&M University
Hole: U1508C
Expedition: 371
Location: Tasman Sea
Latitude: 34° 26.8905' S
Longitude: 171° 20.2558' E
Logging date: August 31, 2017
Sea floor depth (driller's): 1619.7 m DRF
Sea floor depth (logger's): 1617 m WRF (MSS/HRLA/DSI/HLDS/HNGS/EDTC-B downlog)
Total penetration: 2324 m DRF (704.3 m DSF)
Total core recovered: 163.12 m (66.5 % of cored section)
Oldest sediment recovered: Not specified
Lithology: Gray nannofossil chalk with forminifers
ACOUSTIC TOOL USED: DSI (Dipole Sonic Imager)
Recording mode: Monopole P&S and Upper and Lower Dipole (all passes).
Remarks about the recording: none.
MONOPOLE P&S MODE: measures compressional and hard-rock shear slowness. The monopole transmitter is excited by a high-frequency pulse, which reproduces conditions similar to previous sonic tools.
UPPER DIPOLE MODE: measures shear wave slowness using firings of the upper dipole transmitter.
LOWER DIPOLE MODE: measures shear wave slowness using firings of the lower dipole transmitter.
Acoustic data are recorded in DLIS format. Each of the eight waveforms generally consists of 512 samples, each recorded every 10 (monopole P&S) and 40 microsec (dipolemodes), at depth intervals of 15.24 cm (6 inches).The original waveforms in DLIS format are first loaded on a virtual PC machine using Schlumberger's Techlog log analysis package. The packed waveform data files are run through a module that applies a gain correction. After they are exported from Techlog in LAS format, they are converted into binary and GIF format (images) using in-house software.
Number of columns: 4097
Number of rows: 4280 (downlog)
Number of rows: 2854 (main pass)
Number of rows: 829 (repeat pass)
The following files have been loaded:
DSI from HRLA/MSS/DSI/HLDS/EDTC-B/HNGS (Downlog, drill pipe at m 87.5 WMSF)
371-U1508C_ldip_d.bin: 0-660 m WSF
371-U1508C_mono_d.bin: 0-660 m WSF
371-U1508C_udip_d.bin: 0-660 m WSF
DSI from HRLA/MSS/DSI/HLDS/EDTC-B/HNGS (Main pass, recorded open hole)
371-U1508C_ldip_main.bin: 263-706 m WSF
371-U1508C_mono_main.bin: 263-706 m WSF
371-U1508C_udip_main.bin: 263-706 m WSF
DSI from HRLA/MSS/DSI/HLDS/EDTC-B/HNGS (Repeat pass, recorded open hole)
371-U1508C_dip_rep.bin: 572-706 m WSF
371-U1508C_mono_rep.bin: 572-706 m WSF
371-U1508C_udip_rep.bin: 572-706 m WSF
The sonic waveform files are depth-matched and depth-shifted to the seafloor (-1617 m). Please refer to the 'depth_matches' folder in the hole index page for the depth-matching values and to the "DEPTH SHIFT" section in the standard processing notes for further information.
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 .