US3434104A - Hydrophone cable - Google Patents

Description

United States Patent Ofice 3,434,104 Patented Mar. 18, 1969 1 Claim ABSTRACT OF THE DISCLOSURE This invention provides a new type of hydrophone cable section wherein a body of cellular material such as foamed polyurethane is provided with cavities in its exterior surface, in which crystal detectors are recessed, and the body is enclosed by a waterproof jacket. Flotation liquid is contained in the space between the outer jacket and the body, and strain members and electrical conducting wires are enclosed within the body, the combination producing a cable section which will not lose its entire flotation ability nor its ability to protect the crystal detectors and wires even though the outer jacket may be ruptured by contact with external bodies.

This invention relates to a hydrophone cable and more particularly to a hydrophone cable constructed of a plurality of sections which are so constructed and arranged as to provide maximum protection to the sensing devices carried thereby.

It is a general object of the present invention to produce a new and improved hydrophone cable section of the character described in the preceding paragraph.

It is a more specific object of the invention to provide a hydrophone cable section which includes a cellular interior body possessing flotation characteristics and in which a plurality of crystal detectors are located in recessed portions of the body so as to be protected from damage by encounter with external objects.

Hydrophone cables, often of considerable length, are utilized rather extensively in the seismic exploration for offshore oil deposits. The ordinary cable section is provided with a waterproof exterior cover which encloses a flotation liquid, usually kerosene, and also encloses the electrical sensing devices such as crystal detectors and accompanying wiring. Additionally, a strain member usually in the form of a wire cable, extends through the sections in order to bear the strain when towing long lengths of hydrophone cable through the water. In the event a cable section of the type just described encounters a foreign object so as to rupture the outer cover, the flotation liquid is lost and, additionally, water is allowed to enter, damaging the components and also destroying the flotation characteristics of the cable through loss of the flotation liquid. As a result, the hydrophone cable may sink to the bottom of the body of water being explored and be further damaged or lost.

According to the present invention, however, the hydro phone cable section includes a central core or body of cellular material surrounded by an outer waterproof jacket, with kerosene or other flotation liquid being provided in the space between the body and the outer cover. Additionally, the crystal detectors are enclosed in a separate waterproof cover or jacket and the conducting wires pass through the interior of the body. Accordingly, even though such a hydrophone cable section should encounter a sunken object and the outer cover ruptured with the resultant loss of flotation fluid, the inherent flotation characteristics of the cellular body serve to provide buoyancy for the apparatus and the separate waterproof cover enclosing the crystal detectors prevent their damage by entering sea water. The conductor wires extending through a central portion of the body are similarly protected from damage or corrosion by salt water with the result that hydrophone cables constructed in accordance with the present invention exhibit an ability to withstand damage without destruction of the cable and to continue to function efficiently and effectively even after suffering damage which would render inoperable hydrophone cables of other construction.

The foregoing objects and advantages of the invention will be readily apparent from the following description and drawings, in which:

FIGURE 1 is an elevational view of a hydrophone cable made up of a plurality of hydrophone cable sections;

FIGURE 2 is an enlarged plan view of a single hydrophone cable section;

FIGURE 3 is an enlarged vertical longitudinal sectional view of a portion of a cable section;

FIGURE 4 is a horizontal longitudinal section of the cable shown in FIGURE 3; and

FIGURE 5 is a transverse vertical section taken along line 55 of FIGURE 4.

While this invention is susceptible of embodiment in many different forms, there is shown in the drawings and will herein be described in detail a specific embodiment of the invention with the understanding that the present disclosure is to be considered as an exemplification of the principles of the invention and is not intended to limit the invention to the embodiment illustrated. The scope of the invention will be pointed out in the appended claim.

Referring now to the drawings, there is shown a hydrophone cable 10 which is made up of a number of cable sections 11. Each cable section may be from 300 to 900 feet long and the hydrophone cable 10 is made up of a plurality of typical sections, each approximately 600 feet long, there being some twelve or more sections in each complete cable thereby providing an over-all length in excess of 7,000 feet. In a hydrophone cable of the type shown in FIGURE 1 there are normally about 24 detector circuits plus spare circuits, making a total on all of 30 to 40 circuits. As shown in FIGURE 2, two circuits are provided in each cable section, namely, detector circuits 12 and 13. Each circuit may have from 1 to 30 crystal detectors electrically connected in parallel, in series, or in series parallel. The detectors are connected to the high side of a step down transformer (not shown) and the low side of such transformer is then connected to the appropriate circuit.

The cable section of the present invention includes a body 14 of cellular material (preferably foamed polyrurethane) which extends generally from end to end of the cable section. The body 14 is provided with a central opening 15 through the center of which extends a strain member in the form of a cable 16. The strain members of each section are connected together so that the cable bears the strain of towing the entire hydrophone assembly through the water. A waterproof jacket, preferably of polyvinyl chloride encloses the cable 16.

The wires interconnecting the various circuits are shown as at 18 and surround the jacket 17. A second polyvinyl jacket 19 surrounds the outer periphery of the wires so as to protect them from any salt water leaking into the cable section.

Extending along an exterior surface of the cellular body 14 is a cavity 20 in which is located a crystal detector 21 of usual construction. The detector 21 includes a cavity 22 beneath the detector so as to permit the same to deflect thereinto when pressure waves encounter the hydrophone cable section. From each crystal detector 21 wires 23 extend and are wrapped around a connector 24. The wires eventually extend into and are connected to the circuit wires 18 extending along the interior of the cellular section. A waterproof jacket 25, again preferably of polyvinyl chloride, encloses each of the crystal detectors but is so arranged as to transmit to the crystal detectors shock waves resulting from explosions or the like utilized in seismic exploration.

The outer surface of the hvdrophone section comprises an outer cover 26, again of polvvinyl chloride, which is spaced from the body 14 by means not shown so as to provide a space 27 therebetween. A flotation fluid, usually kerosene 28, fills the space 27 and provides the primary buoyant force.

The hydrophone cable of the present invention is used in the same manner as previous hydrophone cable. However, it will be seen that if the outer cover 26 is ruptured, such as by striking a submerged object, the resulting loss of the flotation liquid 28 will not deprive the cable section of its entire buoyancy, the cellular structure of the body 14 providing reserve buoyancy and thus preventing the entire hydrophone cable from sinking to the bottom. Even though the space 27 be flooded by salt water, the jacket 25 will continue to protect the crystal detectors from salt water and the jackets 17 and 19 protect the wires and cable from the damaging effects of salt water immersion so that the entire hydrophone cable assembly may continue to be used and will continue to function successfully even after suffering damage which would render ordinary hydrophone cables inoperative.

Thus, it will be readily apparent to those skilled in the art to which the invention pertains that the present invention provides a hydrophone cable of unusual durability coupled with the capability of continued functioning even after extensive damage and flooding.

We claim:

1. A hydrophone cable construction comprising a plurality of cable sections, each section including an elongated body of foamed cellular material, an opening extending centrally and longitudinally through the body, a strain cable extending continuously through said central opening, a first waterproof jacket enclosing the cable, a plurality of electrical conductors in said central opening and surrounding said jacket, a second waterproof jacket enclosing said electrical conductors, a crystal detector positioned in a cavity formed in the exterior surface of the body, a waterproof cover enclosing said crystal detector, means electrically connecting said crystal detector to said electrical conductors, a third waterproof jacket enclosing the body and spaced therefrom, and a. fluid having a specific gravity of less than 1 in said space to provide buoyancy to said section.

References Cited UNITED STATES PATENTS 2,864,073 12/1958 Harris 3407 2,923,916 2/1960 Woodworth 3407 3,353,150 11/1967 Jacox 34010 RODNEY D. BENNETT, Primary Examiner.

C. E. WANDS, Assistant Examiner.

U.S. C1. X.R. 340-10

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