Abstract: 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.

Abstract: 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).

Abstract: The liquid slug projector apparatus is entirely pneumatically operated. It comprises a generator having a main housing whose main port fluidly communicates with a liquid body. A first shuttle and a second shuttle are slidably mounted inside the main housing. The first shuttle forms with the main housing a slug chamber for confining therein a liquid slug. A pneumatic source together with a pneumatically-operated valve cyclically cause the shuttles to move relative to or in locked condition with each other, thereby applying during each cycle of operation an abrupt propulsion force to the confined liquid slug which becomes expelled as a very high-velocity liquid jet through the main port.

Abstract: A quantity of a solution of a long-chain polymer is injected into the water around an air gun. The resulting dilute solution of the long-chain polymer tends to reduce turbulence surrounding the air bubble that is created when the gun is fired.

Abstract: The invention is a device known generically as an "air gun" suitable for producing a shock wave in a subsea environment during seismic prospecting. It is made up of a central chamber holding pressurized gas. The gas is released explosively into the water by moving a double acting shuttle. The shuttle seals the central gas chamber at each end of its stroke. A novel pneumatic actuator is also shown.

Abstract: An armored umbilical and termination housing is disclosed for towing a sub-array of seismic air guns used in marine seismic surveying comprising a single air hose for supplying all the high pressure air to the individual air guns surrounded by all the electrical control cables needed to operate the air guns in the sub-array. Protective coatings are applied around the electrical control cables and stress members for carrying the laod of towing the sub-array are incorporated within the umbilical. A termination housing is provided on the end of the umbilical for terminating the single air hose and all the electrical control lines to common connectors so that individual electrical control lines and air hoses can run from the termination housing to each individual air gun in the sub-array. Air shut off valves are provided so that the high pressure air can be shut off to the individual air guns within the sub-array remotely from the survey vessel.

Abstract: A gun shot control unit for a seismic exploration system compensates for the inherent delay between the shot command signal and the actual occurrence of the seismic pulse. A digital clock is synchronized with an external source. Timing pulses occurring at a time preceding the timing pulse upon which the occurrence of a seismic pulse is desired are produced by the clock. These timing pulses start a digital counter at a time preceding the desired time of occurrence of the seismic pulse. This counter is adjustable so that the delay which interposes between the timing and the actual occurrence of the seismic pulse can be minimized.

Abstract: An air gun of the reciprocating shuttle type includes a split-ring sleeve valve that is expandable against the inner wall of a firing chamber. The sleeve valve encircles the shuttle body. The shuttle body and the sleeve valve include a set of air release orifices that are alignable with a corresponding set of air exhaust ports of the firing chamber.

Abstract: A seismic method and apparatus utilizes two point sound sources located at the same location on the earth to produce sound waves at different amplitudes and times. The reflections of the sound waves are analyzed to determine the acoustic properties and rock boundaries within the earth.

Abstract: In order to determine the signature of an array of n seismic sources 21 to 27, for instance marine seismic sources in the form of air guns, the array is actuated and the emitted pressure wave is measured at n independent points whose positions will respect to the array are known by hydrophones 31 to 37. The measurements are processed to produce n equivalent signatures of the n sources taking into account the interactions therebetween. The signature of the array is then determined merely by superposing the n equivalent signatures.

Abstract: A sleeve shuttle air gun is described which can be fired by a solenoid valve without dumping compressed air into the ambient prior to firing, thereby avoiding the generation of premature impulses caused by such dumping and avoiding the heavy duty complex solenoid dump valves and two-stage dump valves of the prior art. The sleeve shuttle is automatically returned to its initial closed and sealed position after each firing of the airgun by the refilling flow of only one level of pressurized air without a separate low level pressure source to control the sleeve shuttle. A long acceleration path is provided so the sleeve shuttle attains velocity prior to opening the discharge ports for producing a sudden, powerful discharge. The end of the sleeve shuttle travels completely beyond the discharge ports, and is then damped by interaction with damper ports located beyond the discharge ports.

Abstract: A new circuit is added to the old electrical circuit including two electrodes underwater positioned very close to a gas exhausting gun gaseous exhaust such as an air gun, wherein the exhaust from the firing gas exhausting gun momentarily blows away the conductive sea water from one or both of the electrodes to produce a high voltage pulse due to the large increase in resistance in the circuit indicating the precise moment of firing of the gas exhausting gun.This new circuit added to the above circuit is a circuit polarity reversing circuit which includes particularly a positive current generator, a negative current generator, and a sea ground for forming a third electron source when any of the two electrodes becomes defective, thus forming a fail-safe system.

Abstract: New methods are disclosed for detecting the instant of firing of a gas exhausting gun such as an air gun which reduce plating action on two closely spaced apart electrodes submerged underwater very close to the gas exhausting gun exhaust comprising the basic steps of passing a current through the two electrodes, and periodically reversing the current to the two electrodes responsive to a polarity reversing circuit means after (1) a predetermined period of time or (2) after each firing of the gas exhausting gun.Likewise new methods for forming and assembling a fail-safe gas exhausting gun firing detection circuit are set forth in detail.

Abstract: A robust air gun fire time sensor consists of a housing to which is secured a protruding nonmagnetic internal barrel having a bore. The bore is closed at one end by a magnetic end cap defining an air chamber and the bore is in fluid communication with the firing chamber of an air gun. A generator coil surrounds the barrel. A bar magnet is floatingly mounted inside the bore and is urged against a shoulder formed in the end cap. When the air gun is charged with compressed air, some of the air becomes entrapped in the air chamber. When the air gun is fired, the entrapped compressed air in the air chamber pushes the bar magnet away from the shoulder. The collapsing magnetic field creates a transient electric pulse in the generator coil.

Abstract: The present invention provides a method for determining the spacing and size of air guns in a tuned air gun array. Volume ratios are calculated based upon a predetermined maximum volume for any individual air gun. The volumes are cross-referenced to spacings for optimum air gun interaction. The resulting air gun array operates as a broadband high-energy point source.

Abstract: A compressed-gas seismic energy source suitable for underwater prospecting. The device has two gas storage cylinders placed at the opposite ends of a shuttle. The shuttle seals both storage cylinders when seated at the end of its stroke and releases gas for the desired sonic pulse from both cylinders during its stroke. Design of the device provides for simplicity of operation, ready modification of the sonic signature, and reliability of moving parts.

Abstract: Methods and devices are disclosed for generating acoustic pulses in a water or land medium, e.g., for use in seismic investigations. The pulse amplitudes, waveshapes, and frequencies can be controlled by signals that may originate at a remote location. Compressed gas is confined at high pressure in a valve chamber (12, 194). An initiating signal causes the opening of a passage (54, 56, 192) from the chamber into the medium to initiate the rise of a pressure pulse therein. A second signal causes the closing of the passage in a manner such that the initial rise of the pressure pulse is limited by the closure of the passage. In one device, the passage is opened by one sleeve valve member (60) and closed by another sleeve valve member (58). In another device the passage is opened by a sleeve valve member (196) whose motion to open the passage is arrested substantially instantaneously by transferring its momentum to a momentum exchange sleeve (246) that is then gradually decelerated.

Abstract: Disclosed herein are improvements in a recoil reducing system of a gas gun which create pulses in a liquid medium by introducing therein gas under high pressure. The release of high pressure gas from the barrel of such a gas gun causes recoil of the barrel. To reduce recoil, a reaction plate is attached to the barrel by metal rods so that the high pressure gas will impinge upon the reaction plate before escaping into the medium, and the force exerted on the reaction plate by the impinging gas will at least partially balance the force of recoil. In a preferred embodiment of this invention, a layer of shock absorbent material is interposed between the reaction plate and the impinging gas to absorb some of the energy of the gas. Flexing of the metal rods is thereby reduced and the life of the rods is extended. Alternatively, the flexing of the rods is reduced by connecting each rod to the reaction plate through a chain link type of connection comprising two rings, each ring passing through the other ring.

Abstract: A shuttle valve is slidingly provided within a firing chamber. A shuttle valve actuation control chamber is mounted at each end of the firing chamber. Pressurized air applied to a control chamber at one end of the firing chamber drives the shuttle valve to the opposite end of the firing chamber. An air accumulator chamber having a pressurized-air inlet is mounted adjacent each control chamber. An air passageway having a choke interconnects the firing chamber with the air accumulation chamber. A poppet valve interconnects each accumulator chamber with the adjacent control chamber to selectively apply pressurized air to one or the other of the control chambers. A solenoid vent valve fluidly communicates with each shuttle valve actuation control chamber. A bypass line fluidly interconnects each control chamber with the solenoid vent valve at the opposite end of the firing chamber.

Abstract: There is disclosed apparatus for controlling the precise time of firing of each air gun in an array of air guns employed in marine seismic exploration. For each air gun in the array, the apparatus maintains a record of past measured gun delays, that is the time period expiring between the triggering of an air gun and the time that the gun actually fires. Upon the receipt of a fire command, the apparatus inserts appropriate delays before triggering the individual air guns. In this way the air guns are controlled to fire in a precise predetermined sequence. The air guns may be caused to fire either simultaneously or sequentially so as to exercise effective control over the spectral content and the directionality of the energy generated by the array.

Abstract: The resistive sensor consists of a pair of electrodes separated by an impervious insulating material. The sensor is mounted adjacent to an exhaust port of an airgun, in the path of the air blast that results when the gun is fired. When the air gun is submerged and not activated, the surrounding water creates a low-resistance path between the electrodes. When the gun is fired, the air blast blows the water away from the electrodes and the resistance between them abruptly increases substantially. A bridge circuit detects the instant of resistance change and generates an electrical transient to mark the time that the gun fired.

Abstract: Apparatus for controlling a release of pressurized fluid, to generate an acoustic or shock wave impulse for use in underwater reflection seismic surveys. Compressed air is supplied to the acoustic impulse generator and is used both to provide the compressed air acoustic impulse and to retain two piston members in sealing engagement with each other to maintain the compressed air within the apparatus. The two internal pistons are hollow, open-ended cylindrical members, and are adapted to slide axially within a cylindrical chamber and abutt one another to preclude escape of compressed air. To fine the acoustic impulse generator, compressed air pressure holding the first piston member in position over a series of exhaust ports is suddenly reduced, causing that piston to shift within its chamber, exposing the ports to atmosphere and thereby emitting an acoustic impulse of compressed air.

Abstract: Apparatus for generating an acoustic pulse in a medium including an upstanding cylindrical housing within which an impact piston retained in the upper end of housing by an electrically controlled latch is driven downwardly by compressed gas to strike a target plate positioned adjacent the bottom of the housing. The compressed gas is provided by high volume accumulators interconnected with large area ports penetrating the sidewall of the housing near its top. The tapered upper portion of the piston presses against static seals mounted on the correspondingly tapered housing bore above and below these ports. This taper enables the compressed air to exert a positive break away force on the piston. Quick release of the latch triggers the downward thrust of the piston to deliver a blow against the target plate.

Abstract: Airgun apparatus are disclosed providing high strength, high pressure and large volume capabilities. An integral high-strength cylindrical housing extends for the full length of the airgun and gives a sleek overall cylindrical configuration. The components of the airgun advantageously are assembled within this cylindrical housing in two groups by sliding them in through the upper or lower end, respectively; moreover, either of the groups of components can be removed independently of the other. The components are pressed firmly together in place within the cylindrical housing by a strong screw-jack type of holding action, and tightening and locking apparatus is included on the airgun itself for enabling the mechanic to tighten and lock the holding means with enormous mechanical advantage.

Abstract: Disclosed is a seismic source device, known in the industry as an air gun, having internal sleeve and shuttle control for allowing a predetermined discharge of compressed air into water for purposes of seismic exploration. The shuttle engages an internal sleeve having ports that momentarily align with exhaust ports and then moves past, sealing off the exhaust ports before all of the compressed air in the firing chamber of the air gun is exhausted. By preventing further discharge of air with little or no loss in acoustic output, pulses are greatly reduced, thereby enhancing the operation of the entire system. Further by preventing all the air in the firing chamber from being discharged, the system becomes more efficient and more cost effective.

Abstract: Firing of a seismic source of the type called an air gun is detected by means of a fluid pressure sensor located in the housing of a solenoid actuated control valve. Through a pressurized gas support port the pressure sensor is in fluid contact with a shuttle-operating chamber of the air gun, and the sensor detects a surge in fluid pressure resulting from rapid motion of the shuttle. if a misfire or malfunction of the air gun is detected by means of the fluid pressure sensor, the malfunctioning air gun can be shut down by actuating the solenoid valve, which is a novel dual action solenoid valve, thereby preventing pressurized gas from being supplied to that particular air gun. The valve includes a valve stem with radial gas inlet ports and radial triggering ports. A solenoid plunger is movable to close one or the other of the sets of ports.

Abstract: Disclosed is a seismic source device, known in the industry as an air gun, having shuttle control for allowing a predetermined discharge of compressed air into water for purposes of seismic exploration. The shuttle is controlled by secondary shuttle means for closing the exhaust ports before all of the compressed air in the firing chamber of the air gun is exhausted. This point of closing the exhaust ports before virtually all of the compressed air is discharged differs from prior art air guns. By preventing further discharge of air, secondary pulses are greatly reduced, thereby enhancing the operation of the entire system. Further, by preventing all the air in the firing chamber from being discharged, the system becomes more efficient and more cost effective.

Abstract: Disclosed is a seismic source device, known in the industry as an air gun, having shuttle and external sliding valve control for allowing a predetermined discharge of compressed air into water for purposes of seismic exploration. The shuttle is controlled by air pressure to move it upward, thereby permitting compressed air in the firing chamber to exhaust through exhaust ports. The external sliding valve had been held in a downward position by air pressure supplied from the firing chamber, compressing a spring. As the firing chamber pressure drops, the compressed spring expands, forcing the sliding valve to move upward, closing the exhaust ports. By preventing further discharge of air, secondary pulses are greatly reduced, with little or no loss in acoustic output, thereby enhancing the operation of the entire system. Further, by preventing all the air in the firing chamber from being discharged, the system becomes more efficient and more cost effective.

Abstract: Disclosed is a seismic source device, known in the industry as an air gun, having shuttle control for allowing a predetermined discharge of compressed air into water for purposes of seismic exploration. The shuttle is indirectly controlled by a moveable plate for closing the exhaust ports before all of the compressed air in the firing chamber of the air gun is exhausted. In one embodiment, the plate is freely moveable; in a second embodiment, the plate is attached to the shuttle. By preventing further discharge of air, with little or no loss in acoustic output, secondary pulses are greatly reduced, thereby enhancing the operation of the entire system. Further by preventing all the air in the firing chamber from being discharged, the system becomes more efficient and more cost effective.

Abstract: An improved air gun consists of an elongated cylindrical housing for containing a volume of compressed air that is closed at each end by end plates. A radially-positioned exhaust port is bored into the wall of the housing. A hollow, cylindrical shuttle, is mounted concentrically inside the housing for linear back-and-forth sliding motion in alternate strokes. The ends of the shuttle are closed by end faces. A radially positioned sealing pad has an orifice that is alignable with the exhaust port is supported by the shuttle. When the shuttle is at either end of a stroke, the sealing pad blocks the exhaust port. The space between each shuttle end face and the respective housing end plates form shuttle-actuation control chambers. A small air leak in each control chamber maintains the residual air pressure therein at ambient when the guns is inactive. To fire the gun, a small quantity of air is diverted by valving from inside the housing to one of the control chambers.