Sonic Waveform Data
Site: Lamont-Doherty Earth Observatory, Palisades, NY
Well: Lamont Test Well 3 (TW-3)
Date: 10/4/2013
Logging Company: Schlumberger
Nominal well diameter (bit size): 6.25 in.
Depth range: 0 -1512 ft
Log Sampling interval: 0.5 ft (6 in)
TOOL USED: Sonic Scanner
Recording modes: Monopole P&S Far (low and medium frequency), Lower and Upper transmitter (medium frequency), Cross Dipole.
Remarks about the recording: none.
Acoustic data are recorded in DLIS format. Each of the eight waveforms generally consists of 512 samples, each recorded every 10 (monopole P&S) and 40 microsec (dipolemodes), 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 and gif images.
Number or rows: 2985 (main)
Number or rows: 1876 (repeat)
Number of columns:
lower/upper monopole: 3329
far monopole: 6657
lower monopole/azimuth: 13313
far monopole/azimuth: 26625
cross dipole: 9920
The following files have been created:
Main Pass from Sonic Scanner/PPC-B/GPIT/EDTC-B
TW3_far_mono_lf_main.bin: 360-1512 ft
TW3_far_mono_mf_azi_main.bin: 360-1512 ft
TW3_far_mono_mf_main.bin: 360-1512 ft
TW3_lower_mono_mf_azi_main.bin: 360-1512 ft
TW3_lower_mono_mf_main.bin: 360-1512 ft
TW3_upper_mono_mf_main.bin: 360-1512 ft
TW3_X_cdip_cl_main.bin: 360-1512 ft
TW3_X_cdip_il_main.bin: 360-1512 ft
TW3_Y_cdip_cl_main.bin: 360-1512 ft
TW3_Y_cdip_il_main.bin: 360-1512 ft
Repeat pass from Sonic Scanner/PPC-B/GPIT/EDTC-B
TW3_far_mono_lf_rep.bin: 574.5-1512 ft
TW3_far_mono_mf_azi_rep.bin: 574.5-1512 ft
TW3_far_mono_mf_rep.bin: 574.5-1512 ft
TW3_lower_mono_mf_azi_rep.bin: 574.5-1512 ft
TW3_lower_mono_mf_rep.bin: 574.5-1512 ft
TW3_upper_mono_mf_rep.bin: 574.5-1512 ft
TW3_X_cdip_cl_rep.bin: 574.5-1512 ft
TW3_X_cdip_il_rep.bin: 574.5-1512 ft
TW3_Y_cdip_cl_rep.bin: 574.5-1512 ft
TW3_Y_cdip_il_rep.bin: 574.5-1512 ft
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 drilling and logging operations can be found in the Operations and Downhole Measurements sections of the expedition report, Proceedings of the Integrated Drilling Program, Expedition 3.
For any question about the data or about the LogDB database, please contact LogDB support: logdb@ldeo.columbia.edu.