Geophysical Company of Norway A.s.

Eldar K Lien

Clive T Snook

Otto Benestad

Sverre Caspersen

Eigil Larsen

An arrangement in a piezoelectric hydrophone that is provided with a protective outer housing enveloping a waterproof closed casing (2). Said casing is provided with two mutually opposed and parallel diaphragm wafers (3) on the insides of which piezoelectric crystals (4) being metal coated on their outsides are respectively attached. A connecting wire is extended from said case through its hollow central portion (6). Said central portion (6) is formed by at least two ceramic elements (7) joined along a plane parallel with the diaphragm wafers and provided with a metalization (11) in the mutual contact areas (9, 10). In the cavities (12) respectively of the two elements (7) stiffening ceramic disks (8) are provided and attached to the elements (7) by the aid of a matching projection (13). The inward facing poles of the piezoelectric crystals are conductively connected with the metalization in the contact plane of the elements, and an additional wire (5) is provided from the metalization (11) on the outside. The poles facing outward of said crystals are connected via said diaphragm wafers (3) on the outside of the casing (2). The ceramic material used is Al.sub.2 O.sub.3 having a degree of purity of more than 85%.

Arrangement in hydrophone

A cable for towing air or water guns behind a seismic vessel is constructed with a reinforced air hose in the center region. The air hose (1) is a Kevlar fiber reinforced high pressure air hose with low air diffusion. Outside the hose, signal conductors are placed which are individually insulated with watertight coating and arranged substantially in a single layer of cylindrical elements (2) that are wound around the air hose (1). The interstices between the elements are filled with a water-repelling lubricant. Outside the layer of cylindrical elements (2) is a protective intermediate jacket (3) not intended primarily to have a water-sealing effect, and this is followed by tension-relieving elements (4) preferably disposed in two layers twisted in opposite directions around the intermediate jacket. An outer protective jacket (5) for the entire cable can be provided on the exterior. A cable constructed in this way provides a solution of the water-sealing problem. It is especially intended for digital data transmission.

Cable for towing air/water guns behind a seismic vessel

A means for terminating of splicing a cable intended for towing air-water guns behind a seismic vessel. The end of the cable, or of each cable section, is guided into the housing of the termination member. The termination is formed with separately located connection sites for the cable components. The cable's tension-relieving wires (3) are guided into a first chamber (I) in the housing and fastened to the supporting structure of the chamber (I), i.e., the housing. The chamber (I) is filled with a water-repellant lubricant. The cable's conductors (9) are guided individually through the first chamber (I) and through a sealed passage (10) in a wall (14) defining a second, watertight chamber (II) which is filled with an electrically insulating, hydrophobic, water-emulsifying liquid. The chamber (II) is also provided with a pressure compensator (8). The conductors (9) are guided further to underwater connectors (15) disposed in the diametrically opposed end wall (13) of the housing, optionally with an intermediate connection of electronics circuitry (16). The compressed air hose (17) of the cable is conducted through the first chamber (I) and through a central separate channel (18) in the second chamber (II) to a coupling (19) outside the housing.

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Hosle, Norway

Eldar K Lien