Wireline Sonic Waveform Data

Science operator: CDEX

Hole: C0002P

Expedition: 348

Location: Nankai Trough (NW Pacific Ocean)

Latitude: 33° 18.0507' N

Longitude: 136° 38.2029' E

Logging-while-drilling date: December 26, 2013-January 2, 2014

Sea floor depth (as seen on logs): 1967.5 m LRF

Total penetration: 5025.6 m LRF (3058.1 m LSF)

ACOUSTIC TOOL USED: XBAT (Sperry/Halliburton Azimuthal Sonic and Ultrasonic LWD Service)

Acoustic data are recorded in DLIS format. Each type of waveform (monopole and dipole) consists of respectively 512 and 700 samples, recorded by six receivers along four arrays (a, b, c, d) every 10 microsec at irregular depth intervals (approximately 8 cm). The original LWD data in DLIS format was first uploaded using GeoFrame software. The waveform data were then exported into ASCII and finally converted into binary format.

Each row of the binary file is composed of the entire waveform set recorded at each depth for a particular array, preceded by the depth. For example, in the case of 6 waveforms with 512 samples per waveform, this corresponds to 1 + 6x512 = 3073 columns. 

In this hole, the specifications of the files are:

Monopole waveforms:

Number of columns: 3073 (512 samples/waveform)

Number of rows: 10124 (appx 8 cm vertical sampling interval)

Dipole waveforms:

Number of columns: 4201 (700 samples/waveform)

Number of rows: 10118 (appx 8 cm vertical sampling interval)

The following files were converted:

348-C0002P_mono_a.bin: 2136.1666-3031.3672 m LSF

348-C0002P_mono_b.bin: 2136.1666-3031.3672 m LSF

348-C0002P_mono_c.bin: 2136.1666-3031.3672 m LSF

348-C0002P_mono_d.bin: 2136.1666-3031.3672 m LSF

348-C0002P_dip_a.bin: 2136.2569-3031.3727 m LSF

348-C0002P_dip_b.bin: 2136.2569-3031.3727 m LSF

348-C0002P_dip_c.bin: 2136.2569-3031.3727 m LSF

348-C0002P_dip_d.bin: 2136.2569-3031.3727 m LSF

The binary files are depth-shifted to the sea floor (- 1967.5 m).

The depth and the data are stored as 4-bytes ieee floating point numbers.

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 and more detailed information about the drilling and logging operations and the quality of the measuremets performed can be found in the Operations and Logging sections of the expedition report, Proceedings of the Integrated Drilling Program, Expedition 348.

For questions about the online database, please contact:

Cristina Broglia

Phone: 845-365-8343

Fax: 845-365-3182

E-mail: Cristina Broglia

For questions about the procesing of the resistivity images, please contact:

Tanzhuo Liu

Phone: 845-365-8630

Fax: 845-365-3182

E-mail: Tanzhuo Liu

For questions about the logs, please contact:

[if !supportEmptyParas]   [endif]

Yoshinori Sanada

E-mail: sanada@jamstec.go.jp