System for marine seismic exploration

Claim 2

An acoustic pulse generator for creating acoustic pulses when submerged in a fluid medium comprising: a. a cylinder having one end closed and one end opened to the fluid medium; b. a piston slidably disposed within and in sealing engagement with said cylinder to provide a chamber of variable volume between the closed end of said cylinder and said piston; c. means for displacing said piston and the closed end of said cylinder to an extended spaced position relative to each other; and d. resilient means in the chamber, for preventing said pisTon from contacting the closed end of said cylinder when said piston or the closed end of said cylinder or both, are accelerated inwardly with respect to the chamber, by the ambient pressure of the fluid medium and for causing said piston or said cylinder or both to rebound outwardly with respect to said chamber to produce an acoustical pressure pulse in the fluid medium surrounding said cylinder.

Claim 3

The acoustic pulse generator of claim 1 wherein the combined mass of said cylinder and the effective water load mass coupled to said cylinder is high with respect to the combined mass of said piston and the effective water load mass coupled to said piston; said cylinder is relatively stationary with respect to said piston; said piston moves to the extended position spaced from the closed end of said cylinder; said piston is accelerated inwardly with respect to the chamber; and said piston rebounds outwardly to produce the acoustical pressure pulse.

Claim 4

The acoustic pulse generator of claim 1 wherein the combined mass of said piston and the effective water load mass coupled to said piston is high with respect to the combined mass of said cylinder and the effective water load mass coupled to said piston; said piston is relatively stationary with respect to said cylinder; the closed end of said cylinder moves to the extended position spaced from said piston, the closed end of said cylinder is accelerated inwardly with respect to the chamber; and said cylinder rebounds outwardly to produce the acoustical pressure.

Claim 5

The acoustic pulse generator of claim 1 wherein the combined mass of said cylinder and the effective water load mass coupled to said cylinder and the combined mass of said piston and the effective water load mass coupled to said cylinder are substantially equal; both the closed end of said cylinder and said piston move when they are being displaced to the extended spaced position relative to each other; both said piston and the closed end of said cylinder, move when they are accelerated inwardly; and both said piston and said cylinder rebound outwardly to produce the acoustical pressure pulse.

Claim 6

The acoustic pulse generator of claim 1 wherein said resilient means is a compressible fluid.

Claim 7

The acoustic pulse generator of claim 5 including holding means for holding said piston and said cylinder in the extended position against the pressure of the fluid medium, and releasing means for releasing said piston and said cylinder from the extended position to permit the pressure of the fluid medium to drive said piston or said cylinder or both inwardly with respect to the chamber.

Claim 8

The acoustic pulse generator of claim 6 wherein said displacing means and said holding means are comprised of a hydraulic cylinder having a plunger connected to said piston.

Claim 9

The acoustic pulse generator of claim 6 including vacuum regulating means for controlling the pressure of the compressible fluid within the chamber.

Claim 10

The acoustic pulse generator of claim 7, wherein said releasing means is comprised of: a. at least one link pivotally connected to the outer surface of said cylinder and pivotally connected to the outer surface of said hydraulic cylinder; b. latch means connected to said link for holding said cylinder and said hydraulic cylinder in one position relative to each other; c. control means for releasing said latch means to permit said link to pivot with respect to said cylinder and said hydraulic cylinder causing said cylinder and said hydraulic cylinder to move relative to one another, whereby the pressure of the fluid medium may accelerate said piston or the closed end of said cylinder or both inwardly with respect to the chamber, and said hydraulic cylinder may move longitudinally with respect to said cylinder.

Claim 11

The acoustic pulse generator of claim 9 wherein said latch means is comprised of an electromagnet and said control means includes an electric circuit which can be deactivated when it is desired to fire the generator.

Claim 12

The acoustic pulse generator of claim 9 including a second link which is pivotally connected to said hydraulic cylinder, and wherein said first link includes a first end which is pivotally connected to said cylinder, and a second end which is pivotally connected to said second link, said second link being aligned at a slight angle to said first link whereby forces, exerted on either said first link or on said hydraulic cylinder, which have a force component parallel to the axis of said first link will tend to pivot said first link and said second link with respect to said hydraulic cylinder.

Claim 13

The acoustic pulse generator of claim 11 wherein said latch means is comprised of an electromagnet which attracts one end of said first link of said releasing means to prevent said first link and said second link from pivoting.

Claim 14

The acoustic pulse generator of claim 12 wherein said control means includes sensing means for sensing the presence of the second end of said first link adjacent said electromagnet and for actuating said electromagnet when the presence of said link is sensed.

Claim 15

The acoustic pulse generator of claim 9 including guide means connected to said hydraulic cylinder and to said cylinder for guiding the relative movement of said hydraulic cylinder and said cylinder.

Claim 16

The acoustic pulse generator of claim 9 including a spider mounted at the open end of said cylinder, and a shaft secured to said piston and concentrically mounted in said spider to support and guide said piston during relative movement of said piston and said cylinder.

Claim 17

An acoustic pulse generator for creating acoustic pulses when submerged in a fluid medium comprising: a. a cylinder having one end closed and one end opened to the fluid medium; b. a piston slidably disposed within and in sealing engagement with said cylinder to provide a chamber of variable volume between the closed end of said cylinder and said piston; c. means for displacing said piston to an extended position spaced from the closed end of said cylinder; d. holding means for holding said piston in the extended position against the pressure of the fluid medium; e. releasing means for releasing the piston from the extended position to permit the pressure of the fluid medium to drive said piston inwardly with respect to the chamber; and f. resilient means in the chamber for preventing said piston from contacting the closed end of said cylinder when said piston is accelerated inwardly with respect to the chamber by the ambient pressure of the fluid medium and for causing said piston to rebound outwardly with respect to the chamber to produce an acoustic pressure pulse in the fluid medium surrounding the cylinder.

Claim 18

An acoustic pulse generator for creating acoustic pulses when submerged in a fluid medium comprising: a. a cylinder having one end closed and one end opened to the fluid medium; b. a piston slidably disposed within and in sealing engagement with said cylinder to provide a chamber of variable volume between the closed end of said cylinder and said piston; c. means for displacing said piston to an extended position spaced from the closed end of said cylinder; d. holding means for holding said piston in the extended position against the pressure of the fluid medium; e. releasing means for releasing the piston from the extended position to permit the pressure of the fluid medium to drive said piston inwardly with respect to the chamber; and f. resilient means in the chamber for preventing said piston from contacting the closed end of said cylinder when said piston is accelerated inwardly with respect to the chamber by the ambient pressure of the fluid medium and for causing said piston to rebound outwardly with respect to the chamber to produce an acoustic pressure pulse in the fluid medium surrounding the cylinder.

Claim 19

The acoustic pulse generator of claim 16 wherein said resilient means is a gas and the generator includes vacuum regulating means for controlling the pressure of the gas within the chamber.

Claim 20

An acoustic pulse generator for creating acoustic pulses when submerged in a fluid medium comprising: a. a cylinder having one end closed and one end opened to the fluid medium; b. a piston slidably disposed within and in sealing engagement with said cylinder to provide a chamber of variable volume between the closed end of said cylinder and said piston; c. a hydraulic cylinder connected to said cylinder and said piston for displacing said piston to an extended spaced position relative to the closed end of said cylinder and for holding said piston in the extended position; d. a gas in the chamber for preventing the piston from contacting the closed end of the cylinder when the piston is accelerated inwardly with respect to the chamber by the ambient pressure of the fluid medium, and for causing the piston to rebound outwardly with respect to the chamber to produce an acoustical pressure pulse in the fluid medium surrounding said cylinder and e. vacuum regulating means for controlling the pressure of the gas within the chamber.

Claim 21

An acoustic pulse generator for creating acoustic pulses when submerged in a fluid medium comprising: a. a cylinder having one end closed and one end opened to the fluid medium; b. a piston slidably disposed within and in sealing engagement with said cylinder to provide a chamber of variable volume between the closed end of said cylinder and said piston; c. a hydraulic cylinder connected to said cylinder and said piston for displacing said piston to an extended spaced position relative to the closed end of said cylinder and for holding said piston in the extended position; d. a gas in the chamber for preventing the piston from contacting the closed end of the cylinder when the piston is accelerated inwardly with respect to the chamber by the ambient pressure of the fluid medium, and for causing the piston to rebound outwardly with respect to the chamber to produce an acoustical pressure pulse in the fluid medium surrounding said cylinder and e. vacuum regulating means for controlling the pressure of the gas within the chamber.

Claim 22

In a method for marine seismic exploration, the steps of: a. submerging, in a body of water, a cylinder having an open end and a closed end with a piston disposed between the ends; b. drawing the cylinder along a predetermined path overlaying the object to be explored; c. periodically establishing a predetermined volume of gas, at a pressure below the ambient pressure of the water, adjacent the closed end of the cylinder; d. permitting the ambient water pressure to accelerate the piston inwardly toward the gas to compress the gas adjacent the closed end of the cylinder, the volume of gas being sufficient to prevent the piston from striking the closed end of the cylinder; e. permitting the compressed gas to cause the piston to rebound against the ambient pressure of the water to produce a large acoustic pressure pulse; and f. monitoring the sequence of acoustical signals reflected from the object.

Claim 23

In a method for marine seismic exploration, the steps of: a. submerging, in a body of water, a cylinder having an open end and a closed end with a piston disposed between the ends; b. drawing the cylinder along a predetermined path overlaying the object to be explored; c. periodically establishing a predetermined volume of gas, at a pressure below the ambient pressure of the water, adjacent the closed end of the cylinder; d. permitting the ambient water pressure to accelerate the piston inwardly toward the gas to compress the gas adjacent the closed end of the cylinder, the volume of gas being sufficient to prevent the piston from striking the closed end of the cylinder; e. permitting the compressed gas to cause the piston to rebound against the ambient pressure of the water to produce a large acoustic pressure pulse; and f. monitoring the sequence of acoustical signals reflected from the object.

Claim 24

The method of claim 19 including the steps of holding the piston and the closed end of the cylinder at an extended position relative to each other while establishing the predetermined volume of gas adjacent the closed end of the cylinder; and when desiring to produce an acoustic pulse, releasing the piston and the cylinder from their extended position to permit the ambient water pressure to accelerate the piston toward the closed end of the cylinder.

Claim 25

An acoustic pulse generator for creating acoustic pulses when submerged in a fluid medium comprising: an expandable and collapsible structure for establishing a chamber or variable volume in the fluid medium; means connected to said structure for displacing said structure to an expanded position to expand the chamber against the ambient pressure of the fluid medium; and resilient means in the chamber for preventing the chamber from complete collapse when said structure is collapsed by the ambient pressure of the fluid medium and for causing said structure to rebound outwardly with respect to the chamber to produce an acoustical pressure pulse in the fluid medium surrounding said structure.

Claim 26

An acoustic pulse generator for creating acoustic pulses when submerged in a fluid medium comprising: an expandable and collapsible structure for establishing a chamber or variable volume in the fluid medium; means connected to said structure for displacing said structure to an expanded position to expand the chamber against the ambient pressure of the fluid medium; and resilient means in the chamber for preventing the chamber from complete collapse when said structure is collapsed by the ambient pressure of the fluid medium and for causing said structure to rebound outwardly with respect to the chamber to produce an acoustical pressure pulse in the fluid medium surrounding said structure.

Claim 27

The acoustic pulse generator of claim 21, wherein said resilient means is a compressible fluid.

Claim 28

The acoustic pulse generator of claim 22 wherein said compressible fluid comprises a gas located in the chamber, the pressure of said gas being reduced to a vacuum pressure less than the ambient pressure of the fluid medium when said structure is expanded.

Claim 29

The acoustic pulse generator of claim 23, including vacuum regulating means for controlling the pressure of the gas within the chamber.

Claim 30

The acoustic pulse generator of claim 21 including holding means for holding said structure in the expanded position against the pressure of the fluid medium, and releasing means for releasing said structure from the expanded position to permit the pressure of the fluid medium to collapse the chamber established by said structure.

Claim 33

The method of claim 26, which includes: regulating the pressure of the compressible fluid in the chamber.