SONIC WAVEFORMS

Drilling operator: Warren George Inc.

Logging operator: LDEO-BRG

Hole: Moodus 1

Location: Moodus Township (Middlesex County, Connecticut)

Latitude: 41° 31.68' N

Longitude: 72° 26.56' W

Logging date: July, 1987

Total penetration: 1458 mbrf (4784 ftbrf)

Total core recovered: Nine 3-m cores were recovered at approximately 150 m intervals

Lithologies: 0-579 m - Granitic gneisses, schists, and granites (Hebron Formation); 579-637 m - Granitic gneisses (Canterbury Gneiss); 637-678 m - Canterbury gneisses interlayered with Tatnic Hill schists ; 678-802 m - Biotite schists and gneisses (Tatnic Hill Formation); 802-1085 m - Granitic gneisses and schists (Waterford Group); 1085-1458 m - Biotite-amphibole gneisses (Lower Avalon Complex)

TOOL USED: SDT (Digital Sonic Tool, also known as Array Sonic)
Recording mode: linear mode (8 receivers)
Remarks about the recording: none

Acoustic data were recorded in LIS format. Each of the eight waveforms consists of 472 samples and is recorded at a sampling rate of 0.1524 m. The original data is first loaded on a Sun system using GeoFrame software. The 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 500 samples per waveform, this corresponds to 1 + 8x500 = 4001 columns. In this hole, the specifications of the file are:
Number of columns: 3777
Number of rows: 4063 (upper section)
Number of rows: 5219 (lower section)
Number of rows: 178 (repeat run, pass 1)
Number of rows: 634 (repeat run, pass 2)
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 to view it.

The following files have been loaded:
SDT from SDT/GR (upper section, fluid level at 83.3 mbrf)
moodus1_u.bin: 66.90-685.92 mbrf
SDT from SDT/GR (lower section, open hole)
moodus1_l.bin: 6567.6-1452.83 mbrf
SDT from SDT/GR (repeat run, pass 1, open hole)
moodus1_r1.bin: 1427.84-1454.81 mbrf
SDT from SDT/GR (repeat run, pass 2, open hole)
moodus1_r2.bin: 638.09-685.92 mbrfi

The sonic waveform files are not depth shifted to a reference run. For depth shift to the sea floor, please refer to the DEPTH SHIFT section in the standard log documentation file.

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

For any question about the data or about the LogDB database, please contact LogDB support: logdb@ldeo.columbia.edu.