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

Lithologies: limestones.



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: 873 (Main run)

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)



Additional information about the Cajon Pass project is available at:






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