Wireline Sonic Waveform Data
IODP logging
contractor: USIO/LDEO
Hole: U1354C
Expedition: 317
Location: Canterbury Basin (SW Pacific Ocean)
Latitude: 44 °50.8487' S
Longitude: 171° 47.2080 ' E
Logging date: January 2, 2010
Sea floor
depth (driller's):
125 m DRF
Sea floor
depth (logger's):
122 m WRF (DIT/DSI/GPIT/HNGS main pass)
Total
penetration: 509.2 m DRF
Total core
recovered: 133.37 m (
42 % of cored section; no coring 0-65 m DSF)
Oldest sediment recovered: late lower Pliocene (4.0-4.3 Ma
Lithologies: mud, sandy mud, muddy sand, marl, sandy marl, clay
TOOL USED: DSI
(Dipole Sonic Imager)
Remarks about
the recording: The DSI was run with the medium frequency monopole, the standard frequency upper dipole and the low frequency lower dipole for downlog, and with the standard frequency monopole (others remain unchanged) for both repeat and main passes.
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 (256 in cross-dipole mode), each recorded every 10
(monopole P&S) and 40 microsec (all dipole and Stoneley modes), at depth
intervals of 15.24 cm (6 inches). The original data in DLIS format is first
loaded on a Sun system using GeoFrame software. The packed waveform data files
are then converted into 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 + 4x512 = 4097
columns. In this hole, the specifications of the files are:
Number of
columns: 4097
Number of
rows: 2839 (downlog)
Number of rows: 2804 (main run)
Number of rows: 670 (main run)
All values are
stored as 'signed short integers' (= 16 bits signed).
Each file can be
viewed directly as an image with Spyglass transform or NIH image on MAcs and
PCs, or Fortner transform or Khoros on UNIX) - where it has to be opened as
either 'raw' or 'binary matrix'. Any image or signal-processing package should
also allow viewing it.
The following
files have been loaded:
DSI from
DIT/DSI/GPIT/HNGS (downlog, pipe at 230.5 m WRF)
317-U1354C_mono_d.bin: 73.152-505.6632 m WRF
317-U1354C_ldip_d.bin: 73.152-505.6632 m WRF
317-U1354C_udip_d.bin: 73.152-505.6632 m WRF
DSI from
DIT/DSI/GPIT/HNGS (main, pipe at 231 m WRF)
317-U1354C_mono_main.bin: 73.152-505.6632 m WRF
317-U1354C_ldip_main.bin: 73.152-505.6632 m WRF
317-U1354C_udip_main.bin: 73.152-505.6632 m WRF
DSI from
DIT/DSI/GPIT/HNGS (repeat, recorded open hole)
317-U1354C_mono_rep.bin: 78.0288-505.206 m WRF
317-U1354C_ldip_rep.bin: 78.0288-505.206 m WRF
317-U1354C_udip_rep.bin: 78.0288-505.206 m WRF
The sonic
waveform files are not depth shifted to a reference run or to the seafloor. For
depth shift to the sea floor, please refer to the DEPTH SHIFT section in the
standard data processing documentation file.
NOTE: 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 = 2*(1+nwav*nsamples))
where nwav is
the number of waveforms (4 or 8) and nsamples the number of samples per
waveforms (see above).
If the total
number of depths where waveforms have been recorded is ndepth (for a 150 m
interval with data every 15cm, ndepth would be 1000), a generic loop to read
the data would be
do k = 1, ndepth
...
read(1, rec=k)
iz, (data(i), i = 1, nwav*nsamples)
z(k)=float(iz)/10
...
enddo
In such a case,
the file dimensions will be ndepth rows by nwav*nsamples+1 columns
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 317.
For further questions about the logs, 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