The seismic streamer

The GIN-RAS single-channel seismic streamer (Fig.16) was used. The technology is described elsewhere in literature [Edgerton (1963),Ewing and Tirey (1961),Linarski (XXXX)]. However, it was modified to allow high speed data acquisition (8-12 kn) and to increase performance by developping an efficient stretch section made-up by a vacuum-filled polyurethane hose.

figure

Figure 16: Single channel streamer.

The streamer consists of the following parts (from dry-end to tail):

• Tow leader. 120m long Model KG3-40-90 three conductor wires (0.008 Ohm/m) within an armored two layers zinc plated steel shield, breaking force: 4000 kg. .
• Impedance matching. Construction: transformer placed between tow leader and stretch section. Coefficient transformation: 0.2. Magnetic material: permalloj. Resistance of primary: 1.1 kOm, resistance of secondary 40 Ohm
• Stretch section. Construction: GIN-RAS. 10 m long vacuum filled polyurethane hose
• Active section. Construction: the receiver antenna is placed within a polychlorvinil hose filled with diesel fuel. Length of hose: 30 m. Outside diameter of hose: 54 mm. Thickness of hose: 5 mm. Trade mark of ceramic: PDS-21. Number ceramic elements: 50 Step of ceramic elements: 0.5 m. Connection of the ceramics: parallel. Length of the antenna: 25 m.
• Tail Section. Length of the hose: 10 m. Outside diameter of the hose: 36 mm. Thickness of the hose: 4 mm.
• Stabilizer. Rope diameter 10 mm. Length: 30 m.
• Connectors.Construction: GIN-RAS. Designed to keep the conductors in a pressurized environment, to provide stronger waterproofness. Number contacts: 3.Pressure on the contact: 600 bar. Pressure of air within the contact zone: 100 bar.