Wireline Sonic Waveform Data
Science operator: DOSECC/USGS
Logging operator: Schlumberger, Welex
Hole: Cajon Pass Federal 2-26
Location: Cajon Junction, San Bernardino Mountains, California
1144 ft S and 1982 ft E from NW corner of Sec. 26, Twp. 3N, Rge. 6W
Logging dates:
Upper Section: February 11, 1987 (DLL/MSFL/GR), February 12, 1987 (LDT/CNTG/NGT, ACT/GST/NGT), February 13, 1987 (SDT/GR logs), February 14, 1987 (FMS/GPIT/NGT)
Lower section: March 15, 1988 (DLL/MSFL/GR), March 16, 1988 (SDT/GR, LDT/CNT/NGT, ACT/GST/NGT), March 18, 1988 (FMS/GPIT/NGT) April 6, 1988 (Borehole Geometry with Inclinometry)
Elevation (kelly bushing):1009.2 m (3311 ft)
Elevation (ground level): 994.5 m (3279 ft)
Casing: 13 3/8 in at 250.5 m (822 ft)
Casing: 9 5/8 in at 1828.8 m (6000 ft)
Lithologies: sandstone, granodiorite, granite, gneiss.
Sediment/basement contact: 500 m (1640 ft), from GR log.
ACOUSTIC TOOL USED: SDT (Digital Sonic Tool, also known as Array Sonic)
Recording mode: Linear mode, measuring compressional, shear, and Stoneley velocity. Note: the available acoustic dataset is missing the uppermost 500 m of the logged interval.
Each of the nine waveforms
from the upper part of the hole consists of 472 samples, acquired at depth
intervals of 15.24 cm (6 inches). The eight waveforms from the lower part of the hole consist of 490 samples each. The original waveforms are first
loaded on a virtual PC machine using Schlumberger's Techlog log analysis package. The packed waveform data files
are run through a module that applies a gain correction. After they are exported from Techlog in LAS format they are converted into binary and GIF format (images) are converted using in-house software. 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 490 samples per waveform, this corresponds to 1 + 8x512 = 3921
columns. In this hole, the specifications of the files are:
Number of columns: 3921 (Upper section)
Number of
rows: 6441 (Upper section, main pass)
Number of rows: 716 (Upper section, repeat pass #4)
Number of
rows: 1893 (Lower section, interval # 1)
Number of
rows: 775 (Lower section, interval # 2)
Number of
rows: 3644 (Lower section, interval # 3)
Number of rows: 901 (Lower section, interval # 4
Number of
rows: 4239 (Lower section, interval # 5)
The following
files have been loaded:
SDT from SDT/GR (Upper section, main pass)
mono_swfum.bin: 850.83-1832.29 m
SDT from
SDT/GR (Upper section, repeat pass # 4)
mono_swfum.bin: 759.71-868.68 m
SDT from
SDT/GR (Lower section, interval #1)
mono_swfl1.bin: 1787.49-2075.84 m
SDT from
SDT/GR (Lower section, interval #2)
mono_swfl2.bin: 2065,32-2183.28 m
SDT from
SDT/GR (Lower section, interval # 3)
mono_swfl3.bin: 2161.94-2717.13 m
SDT from
SDT/GR (Lower section, interval # 4)
mono_swfl4.bin: 2658.46-2795.62 m
SDT from
SDT/GR (Lower section, interval #5)
mono_swfl5.bin: 2787.54-3433.41 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.
The sonic
waveform files are depth-matched to the reference runs. Please refer to the 'depth_matches' folder in the
hole index page for the depth-matching values and to the "DEPTH SHIFT" section in the standard processing notes for further information.
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://agupubs.onlinelibrary.wiley.com/doi/epdf/10.1029/GL015i009p00945
https://link.springer.com/content/pdf/10.1007%2F978-3-642-73455-7.pdf
https://agupubs.onlinelibrary.wiley.com/doi/toc/10.1002/(ISSN)1944-8007.CAJONPS1
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