Wireline Sonic Waveform Data
IODP logging
contractor: CDEX-JAMSTEC
Hole: C0009A
Expedition:
319
Location: Nankai Trough (NW Pacific Ocean)
Latitude: 33° 27.4704' N
Longitude: 136° 32.1489' E
Logging date:
Sea floor
depth (driller's): 2082.3 m LRF
Sea floor
depth (logger's): 2081.1 m WRF
Total
penetration: 3686 m DRF (1603.7 m DSF)
Total core
recovered: 74.7 m
Oldest
sediment recovered:
Late Miocene
Lithologies: Silty mud and mudstone with rare sand and volcanic ash interbeds, abundant wood/lignite fragments
TOOL USED: Multimode Array Sonic Service Tool (MAST)
Recording mode: Upper, Lower, Far Monopole P&S, X-dipole and Y-dipole (online and crossline).
Remarks about
the recording: none.
UPPER/LOWER/FAR MONOPOLE P&S
MODES: measure compressional and hard-rock shear slowness from upper, lower and far monopole transmitters. The transmitters are excited by a high-frequency pulse, which reproduces conditions
similar to previous sonic tools.
X-DIPOLE
and Y-DIPOLE MODES: use alternate firings of upper and lower dipole transmitter, thus allowing
acquisition of orthogonally polarized data for anisotropy studies.
Acoustic
data are recorded in DLIS format. Each of the thirteen waveforms generally
consists of 512 samples in far monopole mode, 763 in X-dipole and Y-dipole modes, and 256 in upper and lower monopole modes, each recorded every 10
(monopole P&S modes) and 40 microsec (X- and Ydipole 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 run through a GeoFrame module that applies a gain correction and then converted into ASCII and finally binary format.
Each
row of the binary file is composed of the entire waveform set recorded at each depth, preceded by
the depth. In the general case of
13 waveforms with 256 samples per waveform, this corresponds to 1 + 4x512 = 3329
columns (6657 columns for 512 samples/waveform, 9920 columns for 763 samples/waveform). In this hole, the specifications of the files are:
Number of
columns:
Number of
columns:
Number of
columns:
Number of
rows: 948 (main run)
Number of rows: 363 (repeat run)
The following
files were converted:
Sonic Scanner from
FMI/GPIT/EMS/MAST/GR/HNGS (Main, casing at 2785 m WRF)
319-C0009A_Xdip_cl_main.bin: 2844.85-2900.02 m WRF
319-C0009A_Xdip_il_main.bin: 2844.85-2900.02 m WRF
319-C0009A_Ydip_cl_main.bin: 2844.85-2900.02 m WRF
319-C0009A_Ydip_il_main.bin: 2844.85-2900.02 m WRF
319-C0009A_lower_mono_main.bin: 2844.85-2900.02 m WRF
319-C0009A_upper_mono_main.bin: 2844.85-2900.02 m WRF
319-C0009A_far_mono_main.bin: 2844.85-2900.02 m WRF
Sonic Scanner from
FMI/GPIT/EMS/MAST/GR/HNGS (Repeat, open hole)
319-C0009A_Xdip_cl_rep.bin: 2844.85-2900.02 m WRF
319-C0009A_Xdip_il_rep.bin: 2844.85-2900.02 m WRF
319-C0009A_Ydip_cl_rep.bin: 2844.85-2900.02 m WRF
319-C0009A_Ydip_il_rep.bin: 2844.85-2900.02 m WRF
319-C0009A_lower_mono_rep.bin: 2844.85-2900.02 m WRF
319-C0009A_upper_mono_rep.bin: 2844.85-2900.02 m WRF
319-C0009A_far_mono_rep.bin: 2844.85-2900.02 m WRF
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 NOT depth-shifted to the seafloor or depth-matched to a reference run. Please refer to the DEPTH SHIFT section in the
standard data processing documentation file for further information about depth-shifting and depth-matching..
NOTE: For users interested in converting the data to a format more suitable for their own purpose, a simple routine to read the binary files would include a couple of basic steps (here in old fashioned fortran 77, but would be similar in matlab or other languages):
The first step is to extract the files dimensions and specification from the header, which is the first record in each file:
open (1, file = *.bin,access = 'direct', recl = 50) <-- NB:50 is enough to real all fields
read (1, rec = 1)nz, ns, nrec, ntool, mode, dz, scale, dt
close (1)
The various fields in the header are:
- number of depths
- number of samples per waveform and per receiver
- number of receivers
- tool number (0 = DSI; 1 = SonicVISION; 2 = SonicScope; 3 = Sonic Scanner; 4 = XBAT; 5 = MCS; 6 = SDT; 7 = LSS; 8 = SST; 9 = BHC; 10 = QL40; 11 = 2PSA)
- mode (1 = Lower Dipole, 2 = Upper Dipole, 3 = Stoneley, 4 = Monopole)
- vertical sampling interval *
- scaling factor for depth (1.0 = meters; 0.3048 = feet) *
- waveform sampling rate in microseconds *
All those values are stored as 4 bytes integers, except for the ones marked by an asterisk, stored as 4 bytes IEEE floating point numbers.
Then, if the number of depths, samples per waveform/receiver, and receivers are nz, ns, and nrec, respectively, a command to open the file would be:
open (1, file = *.bin, access = 'direct', recl = 4*(1 + nrec*ns))
Finally, a generic loop to read the data and store them in an array of dimension nrec × ns × nz would be:
do k = 1, nz
read (1, rec = 1+k) depth(k), ((data(i,j,k), j = 1,ns), i = 1,nrec)
enddo
This report was prepared at the Borehole Research Group of the Lamont Doherty Earth Oservatory, based on the processing notes and information provided by the logging staff scientists of Expedition 319. Additional information about the drilling and logging operations can be found in the Operations and Downhole Measurements sections of the expedition reports, Proceedings of the Integrated Drilling Program, Expedition 319.
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