IODP Expedition 337, Hole C0020A - Wireline Sonic Waveform Data

Wireline Sonic Waveform Data

IODP drilling and logging operator: CDEX

Hole: C0020A

Expedition: 337

Location: Offshore Shimokita Peninsula (Japan Sea)

Latitude: 41° 10.5983' N

Longitude: 142° 12.0328' E

Logging date: Sep 9-14, 2012

Sea floor depth (driller's): 1208.5 m DRF

Sea floor depth (logger's): 1208.5 m WRF

Total penetration: 3674.5 m DRF ( 2466 m DSF)

Total core recovered: 198.4 m (75.3 % of the 263.5 m cored interval)

Oldest sediment recovered: Oligocene-Early Miocene

Lithologies: Diatom-rich silty clay, shale, sandstone, siltstone, coal-rich horizons

TOOL USED: DSI (Dipole Sonic Imager)

Recording mode: Monopole P&S and Upper and Lower Dipole (thru casing), Cross-Dipole (online and crossline) and Monopole modes (main and repeat runs).

Remarks about the recording: none.

MONOPOLE P&S MODE: measures compressional and hard-rock shear slowness. The monopole transmitter is excited by a high-frequency pulse, which reproduces conditions similar to previous sonic tools.

UPPER DIPOLE MODE: measures shear wave slowness using firings of the upper dipole transmitter.

LOWER DIPOLE MODE: measures shear wave slowness using firings of the lower dipole transmitter.

CROSS-DIPOLE MODE: uses alternate firings of upper and lower dipole transmitter, thus allowing acquisition of orthogonally polarized data for anisotropy studies.

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 (dipole modes), 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.

Each row of the binary file is composed of the entire waveform set recorded at each depth, preceded by the depth. In the general case of 8 waveforms with 512 samples per waveform, this corresponds to 1 + 8x512 = 4097 columns. In this hole, the specifications of the files are:

Number of columns: 4097 (monopole, upper dipole, lower dipole)

Number of columns: 1025 (cross dipole)

Number of rows: 699 (casing, all modes)

Number of rows: 8049 (main, monopole mode)

Number of rows: 1141 (repeat, all modes)

Number of rows: 1971 (main-interval 1, cross dipole mode)

Number of rows: 1971 (main-interval 2, cross dipole mode)

Number of rows: 1971 (main-interval 3, cross dipole mode)

Number of rows: 2062 (main-interval 4, cross dipole mode)

The following files were converted:

DSI from FMI/DSI/EMS/GPIT/EDTC (recorded thru casing; casing at 1252.9 m WSF)

337-C0020A_mono_csg.bin: 1252.9-1297.87 m WSF

337-C0020A_ldip_csg.bin: 1252.9-1297.87 m WSF

337-C0020A_udip_csg.bin: 1252.9-1297.87 m WSF

DSI from FMI/DSI/EMS/GPIT/EDTC (Main run, casing at 1252.9 m WSF)

337-C0020A_mono_main.bin: 1252.9-2466.77 m WSF

Because the original cross-dipole files were too large for the existing software that creates the binary and gif files, they had to be split into four intervals. The resulting filkes are:

337-C0020A_cd_ldip_crossline_main1.bin: 1252.9-1552.9 m WSF

337-C0020A_cd_ldip_inline_main1.bin:1252.9-1552.9 m WSF

337-C0020A_cd_udip_crossline_main1.bin: 1252.9-1552.9 m WSF

337-C0020A_cd_udip_inline_main1.bin: 1252.9-1552.9 m WSF

337-C0020A_cd_ldip_crossline_main2.bin: 1552.9-1852.9 m WSF

337-C0020A_cd_ldip_inline_main2.bin:1552.9-1852.9 m WSF

337-C0020A_cd_udip_crossline_main2.bin: 1552.9-1852.9 m WSF

337-C0020A_cd_udip_inline_main2.bin: 1552.9-1852.9 m WSF

337-C0020A_cd_ldip_crossline_main3.bin: 1852.9-2152.9 m WSF

337-C0020A_cd_ldip_inline_main3.bin: 1852.9-2152.9 m WSF

337-C0020A_cd_udip_crossline_main3.bin: 1852.9-2152.9 m WSF

337-C0020A_cd_udip_inline_main3.bin: 1852.9-2152.9 m WSF

337-C0020A_cd_ldip_crossline_main4.bin: 2152.9-2466.77 m WSF

337-C0020A_cd_ldip_inline_main4.bin: 2152.9-2466.77 m WSF

337-C0020A_cd_udip_crossline_main4.bin: 2152.9-2466.77 m WSF

337-C0020A_cd_udip_inline_main4.bin: 2152.9-2466.77 m WSF

DSI from FMI/DSI/EMS/GPIT/EDTC (Repeat, recorded open hole)

337-C0020A_cd_ldip_crossline_rep.bin: 1865.4-2039.14m WSF

337-C0020A_cd_ldip_inline_rep.bin: 1865.4-2039.14m WSF

337-C0020A_cd_udip_crossline_rep.bin: 1865.4-2039.14 m WSF

337-C0020A_cd_udip_inline_rep.bin: 1865.4-2039.14 m WSF

337-C0020A_mono_rep.bin: 1865.4-2039.14 m WSF

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-shifted to the seafloor ( -1208.5 m). Please refer 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 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 337. For questions about the database, please contact:

Cristina Broglia

Phone: 845-365-8343

Fax: 845-365-3182

E-mail: Cristina Broglia

For questions about the logs, please contact:

Yoshinori Sanada

E-mail: sanada@jamstec.go.jp

Yukari Kido

Email: ykido@jamstec.go.jp

Yuichi Shinmoto:

Email: shinmoto@jamstec.go.jp