Wireline Sonic Waveform Data
IODP logging
contractor: USIO/LDEO
Hole: U1417E
Expedition:
341
Location: Gulf of Alaska (NE Pacific Ocean)
Latitude: 56°57.5888' N
Longitude: 147° 6.5983' W
Logging date:
Sea floor
depth (driller's):
4199.5 m DRF
Sea floor
depth (logger's):
4200 m WRF
Total
penetration: 4909 m DRF (709.5 m DSF)
Total core
recovered: 146.92 m (42.1
% of 348.7 m; several drilled-down intervals)
Oldest
sediment recovered:
~5 Ma at 400 m DSF
Lithologies: Mud, iceberg-rafted diamict, coarse-grained interval dominated by gravity flows alternate with mud, siltstone and sandstone.
TOOL USED: DSI
(Dipole Sonic Imager)
Recording mode:
Monopole P&S and Upper and Lower Dipole (all passes), Cross-Dipole (online and crossline) and Stoneley mode (pass 1).
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.
CROSS-DIPOLE
MODE: uses alternate firings of upper and lower dipole transmitter, thus allowing
acquisition of orthogonally polarized data for anisotropy studies.
STONELEY MODE:
measures low-frequency Stoneley wave slowness. The monopole transmitter, driven
by a low-frequency pulse, generates the Stoneley wave.
The acoustic data are recorded in DLIS format. Each of the eight waveforms geerally 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 data in DLIS format are first loaded on a Sun system using GeoFrame software. The packed waveform data files are run through a GeoFrame module that applies a gain correction and then converted to ASCII and finally binary format.
Each
line is composed of the entire waveform set recorded at each depth, preceded by
the depth (multiplied by 10 to be stored as an integer). In the general case of
8 waveforms with 512 samples per waveform, this corresponds to 1 + 8x512 = 4097
columns. In this hole, the specifications of the files are:
Number of
columns: 4097
Number of
rows: 3757 (downlog)
Number of rows: 3762 (pass 1, monopole, upper and lower dipole, Stoneley modes)
Number of rows: 1794 (pass 1 1ower, cross dipole mode)
Number of rows: 1971 (pass 1 upper, cross dipole mode)
The following files have been loaded:
DSI from
FMS/DSI/GPIT/EDTC-B/HNGS (Downlog, drill pipe at ~80 m WSF)
341-U1417E_ldip_d.bin: 0-572.4 m WSF
341-U1417E_mono_d.bin: 0-572.4 m WSF
341-U1417E_udip_d.bin: 0-572.4 m WSF
DSI from
FMS/DSI/GPIT/EDTC-B/HNGS (Pass 1, drill pipe at ~82.5 m WSF)
341-U1417E_cd_ldip_cl_p1u.bin: 0-300 m WSF
341-U1417E_cd_ldip_il_p1u.bin: 0-300 m WSF
341-U1417E_cd_udip_cl_p1u.bin: 0-300 m WSF
341-U1417E_cd_udip_il_p1u.bin: 0-300 m WSF
341-U1417E_cd_ldip_cl_p1l.bin: 300-573.16 m WSF
341-U1417E_cd_ldip_il_p1l.bin: 300-573.16 m WSF
341-U1417E_cd_udip_cl_p1l.bin: 300-573.16 m WSF
341-U1417E_cd_udip_il_p1l.bin: 300-573.16 m WSF
341-U1417E_ldip_p1.bin: 0-573.16 m WSF
341-U1417E_mono_p1.bin: 0-573.16 m WSF
341-U1417E_st_p1.bin: 0-573.16 m WSF
341-U1417E_udip_p1.bin: 0-573.16 m WSF
Note: Due to size constraints dictated by the data format conversion software, the cross dipole files have been been split into upper and lower section.
DSI from
FMS/DSI/GPIT/EDTC-B/HNGS (Pass 2, drill pipe at ~80 m WSF)
341-U1417E_ldip_p2.bin: -573.16 m WSF
341-U1417E_mono_p2.bin: -573.16 m WSF
341-U1417E_udip_p2.bin: -573.16 m WSF
All values are
stored as '32 bits IEEE float'.
Any image or signal-processing program should allow to import the files and display the data.
The sonic
waveform files are depth-shifted to the seafloor (-4200 m) but they are not depth-matched to the reference run. 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.
For users interested in reading and
converting the data to a format more suitable for their own purpose, the
fortran declaration used to open the file *.bin would be:
open (1, file = *.bin,access = 'direct', recl = 4*(1+nrec*nsamples))
where nrec is the number of receivers (8 in the case of the DSI) and nsamples the number of samples per waveforms.
If the total number of depths where waveforms were recorded is ndepth (for a 150 m interval with data every 15 cm, ndepth would be 1001), a generic loop to read the data would be
do k = 1, ndepth
...
read(1, rec=1+k) depth(k), ((data(i,j,k), j=1,nsamples),i = 1,nrec))
...
enddo
the first record in each file is a header with some of the file specifications:
- number of depths
- number of samples /trace
- number of receivers
- tool number = 0 (DSI)
- mode (1 = Lower Dipole, 2 = Upper Dipole, 3 = Stoneley, 4 = Monopole)
- vertical sampling interval
- scaling factor for depth
- waveform sampling rate in microseconds
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 Integrated Drilling Program, Expedition 341.
For further questions please contact:
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