MINI-STREAMER, 8 CH (2011)

Click image to enlarge:

8-CHANNEL MINI-STREAMER (2011), SPECIFICATIONS

  Lead-in ..................: 150.00 m
  Active section: 8*6.25m ..:  50.00 m
  Tail .....................:  12.50 m
                              --------
             Total length ..: 212.50 m
             -------------------------

  Deck cable length: 27 m

  Cable diameter, lead-in:  14 mm
  Cable diameter, tail:     32 mm

Power consumption

The streamer is powered by Geometrics DHA-7 Battery Pack, P/N: 0060165-01. It consists of two 5 Amp-hour batteries. Each hydrophone preamplifier draws approximately ±10.8 mA per channel. An 8-channel streamer can be powered continuously for approximately 58 hours (5 Amp-hours divided by 86.4 mA (10.8ma *8 channels)).

STREAMER GEOMETRY REQUIREMENTS

Number of hydrophone groups	8
Group center spacing	6.25 m
Number of hydrophones per group	12
Hydrophone spacing within group	0.5 m
Lead-in length	150 m

RECORDING SYSTEM SPECIFICATIONS

Recording system manufacturer	Geometrics
Model	GEODE
Link to manual with specifications	GeodeNZES-3000ManualRevK4.pdf
Maximum input voltage	2.8 V peak-peak (ref. "Appendix A: Specifications" page 224)
Minimum input voltage	0.2 µV (same reference as above)
Input impedance	20 kohm, 0.02 µF (meaning capacitance in parallell with resistor)
Signal input connector (on cable)	Bendix PT06-24-61S(SR)

This is a voltage input amplifier.

A charge amplifier is normally used with the Mini-Streamer. This is a low-impedance, current input type amplifier, with a fairly low output impedance (suitable for connection to e.g. GEODE and similar types of seismographs).

SEISMIC SOURCE (TYPICAL)

Primary use

The Mini-Streamer will most often be used as a supplement during Ocean Bottom Surveys. In this type of survey, the recording instruments are first put on a gridded line on the ocean bottom. Then the ship turns and fires the seismic energy source over the same line. Operating with offsets (distance between source and first recorder) of tens of kilometres, sometimes several hundred kilometers, the source must be able to output low-frequency, high amplitude signals. In practice, several high-volume airguns are used. The acoustic signal shape of this source is not ideal for the Mini-Streamer, but as a supplementary data acquisition system we just have to make do ...

Number of guns	4
Volume, total	4800 inch³ = 79 Liter
Air pressure	140 Bar
Acoustic output	Primary: 10 Barm Peak-peak: 25 Barm => 248 dB rel. 1 µPa 100 m offset distance between source and first hydrophone -> 40 dB attenuation (spherical spreading), thus 208 dB re. 1 µPa peak-peak at first hydrophone.

Secondary use

Shallow seismics, using sparker as source.

!Reel for mini-streamer

Ebinger hose-reels
- Norwegian representative: Grove Knutsen