Wireline Sonic Waveform Data
Science operator: University of Rhode Island-University of Milano
Logging operator: Schlumberger Italy
Hole: Cismon (APTICORE Program)
Location: Monte Grappa State Road 50 (km 53), Veneto, Italy
Latitude: 46° 2' 43.46" N
Longitude: 11° 45' 46.85" E
Logging dates: January 17-18, 1996
Elevation (ground level): 398 m
Total penetration: 131.8 m
ACOUSTIC TOOL USED: SDT ( Sonic Digital Tool, also known as Array Sonic)
Recording mode: Depth-Derived Borehole-Compensated mode, with a 3'-5'-5'-7' spacing.
Each of the 4 waveforms
consists of 500 samples, acquired at depth
intervals of 15.24 cm (6 inches). The original waveforms were first
loaded on a virtual PC machine using Schlumberger's Techlog log analysis package, then they were exported from Techlog in LAS format and finally converted into binary and GIF format (images) using in-house software. Gain cirrections were applied. 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
4 waveforms with 500 samples per waveform, this corresponds to 1 + 4x500 = 2001
columns. In this hole, the specifications of the files are:
Number of columns: 2001
Number of rows: 378 Repeat run)
The following files have been loaded:
SDT from SDT/NGT (main run)
cismon_m.bin: 8-131 m
SDT from
SDT/NGT (repeat run)
cismon_r.bin: 8-56.54 m
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.
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
Additional information about the Cajon Pass project is available at:
https://riviste.unimi.it/index.php/RIPS/article/view/5330/5382
https://people.clas.ufl.edu/jetc/files/Channelletal2000GSAB.pdf
https://agupubs.onlinelibrary.wiley.com/doi/epdf/10.1029/2009PA001769
Questions about the data available on line can be sent to:
Cristina Broglia
Phone: 845-365-8343
Fax: 845-365-3182
E-mail: Cristina Broglia
Gilles Guerin
Phone: 845-365-8671
Fax: 845-365-3182
E-mail: Gilles Guerin