Universitety of Bergen (UiB)
Institute of Solid Earth Physics (IFJ)
Allé gt. 41, N-5007 Bergen, Norway
Tel: (+47) 5558 3420 Fax: (+47) 5558 9669
email: elab@ifjf.uib.no
Elab: http://www2.ifjf.uib.no

Revision history

Rev.

Description

Date

By

A

Draft

June 10, 2002

OM

 

 

 

 

 

Instrumentation block diagram and description


Fig. 1. Instrumentation block diagram (high pressure air to guns not shown). Click to see larger version.

 

 Pos.   Instrument / unit, manufacturer  Instrument / unit picture Supplier Qty.

 Links
1 Airgun controller "GUNCO"
Mfr.: Getech, Horten, Norway		  IFJ, UiB 1  Instrument web page 
2 Synchronizing Unit
Interface to Survey Computer
Mfr.: In-house IFJ, UiB		 IFJ, UiB 1  Unit web page
3 Airguns
Mfr: SODERA		   IFJ, UiB 4  Spare parts
4 Signal/air harness   IFJ, UiB  3 complete
 + spares 

+ "XMAS three" 

  One Harness comprising (from gun side): 
  • Signals
    • 1 ea Signal pig tail, green (solenoid), mfr. Sodera, p/n SJ-1-GR
    • 1 ea Signal pig tail, blue (sensor), mfr.: Sodera, p/n SJ-1-BU
    • 1 ea signal Y-split, mfr.: AG Geophysical
    • 2 ea 4-way signal cable, terminated in QXA-4/12 conn.,
      Mfr: Geco-Fjord Instruments, 22 m
  • Air hosing
    • 1 ea Adapter JIC ext/int threading 3/4" - 9/16".
      Supplier: Tess, Bergen, p/n 7515-08-06
      Note: Order galvanized units next time!
    • 1 ea Air pigtail, ca. 3 m. 3/4" threading
      Supplier: Tess, Bergen
    • 2 ea Air hosing, 20 m
      Supplier: Tess, Bergen
    • 2 ea adapter, ext/ext threading, 3/4"
      Supplier: Tess, Bergen

 Spares:

  • Signals
    • 2 ea Signal pig tail, green (solenoid), mfr. Sodera, p/n  SJ-1-GR
    • 2 ea Signal pig tail, blue (sensor), mfr.: Sodera, p/n SJ-1-BU
    • 1 ea signal Y-split, mfr.: AG Geophysical
    • 4 ea 4-way signal cable, terminated in QXA-4/12 conn.,
      Mfr: Geco-Fjord Instruments, 22 m
  • Air hosing
    • 6 ea Adapter JIC ext/int threading 3/4" - 9/16".
      Supplier: Tess, Bergen, p/n 7515-08-06
      Note: Order galvanized units next time!
    • 4 ea Air pigtail, ca. 3 m. 3/4" threading
    • 3 ea Air hosing, 20 m
    • 10 ea adapter, ext/ext threading, 3/4"

 "XMAS Three", for air distribution (IFJ, UiB supply)
5 Airgun towing arrangement   IFJ, UiB NA  Part list, for one gun:
  • D-shackle, standard, 20 mm bolt, galvanized.
    Supplier: John Dahle Skipsutstyr, Stavanger, Norway
  • Bow shackle, galvanized, 14mm bolt
    Supplier: Giertsen Skipshandel, Bergen, Norway. p/n 3260024
  • Rope Thimble ('kause') for 24 mm rope, galv.
    Supplier: Giertsen Skipshandel, Bergen, Norway. p/n 3431016
  • 24 mm rope
    Supplier: Giertsen Skipshandel, Bergen, Norway. p/n 3431016
  • Locking string for shackles
6 Streamer
Mfr: Geco-Fjord Instruments		   GI, UiTų 1  
7 Spare streamer
Mfr.: Teledyne		   GI, UiB 1  Unit web page
8 Recording system
Mfr.: Triton-Elics		   GI, UiTų  1  Unit web page
9 Toolbox   IFJ, UiB 1 Content
  •  
10 Misc.   IFJ, UiB NA
  • 1 ea Log book
  • Paper, pencils, pens
  • 20 ea CD-R, for data backup, mfr.: Kodak, supplier www.komplett.no
  • 8 ea Tape, Geco grey

Legend:

  • IFJ = Institute of Solid Earth Physics

  • GI = Department of Geology

  • UiB = University of Bergen

  • UiTų = University of Tromsų

Acquisition parameters

Seismic second = 1.024 s
1 MByte = 1024 * 1024 = 1 048 576 bytes

Parameter Value
Target depth 1 - 1.5 km
Target sound velocity 18-1900 m/s
Shot interval 50 m ( => 24 s interval at 4 knots ship speed)
Sample interval 2 ms (500 Hz)
Recording duration 12 s
No. of channels 1

8 second recording time should be sufficient. Let's make a worst-case calculation by assuming a water depth of 3600m. This yields a 4.8 s TWT through the water column, leaving 3.2 s TWT for the sediment section. Half this time - 1.6 s - is used to actually reach the deepest reflection point. With a sediment sound velocity of 1800 m/s we thus reach (1800 * 1.6) = 2880 m below the sea bottom (the seismic second is actually a bit longer, providing even deeper imaging).

Survey area, lines, data parameters

Norwegian Sea

Line ID (from south) Distance Mean water depth and TWT,
 [Sound speed = 1510m/s]		 No. of shotpoints
[Shot interval = 50 m]
1 225 km 1400 m (1.9 s) 4500
2 215 km 2500 m (3.3 s) 4300
3 153 km 3000 m (4.0 s) 3060
4 155 km 3300 m (4.4 s) 3100

 

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