Abstract: A rapid-fire air gun for generating acoustic pulses in a body of water includes a reservoir of high-pressure air, a shut-off valve, and a throttle valve for admitting air to an attached firing chamber. The firing chamber has an exhaust port that is sealed by a spring-loaded exhaust valve. When the shutoff valve is open, high pressure air is admitted to the firing chamber through the throttle valve at a rate depending upon the effective aperture through the throttle valve. The exhaust valve is set to open at some selected pressure and to close at some lower pressure. When the air pressure in the firing chamber exceeds the pressure setting of the exhaust valve, the valve opens to impulsively release a jet of high pressure air which generates an acoustic pulse. When the air pressure in the firing chamber drops, the valve closes and the air pressure again builds up in the firing chamber. A series of such openings and closings generates a pulse train.

Abstract: Within a stationary upstanding cylindrical housing, a piston and a base member resting on the ground are separated by an expansible detonation chamber. Means are provided for feeding successive charges of a combustible gas mixture into the chamber at a rapid rate and initiating a corresponding series of gas explosions therein. Recoil of the piston following each explosion compresses a first air spring which then forcibly thrusts the piston downwardly. Piston recovery for the next cyclic operation is thereafter slowed by means of a second air spring-dashpot combination.

Abstract: A monopropellant fluid is ignited in a combustion chamber to form a pressurized gas volume which may include the interior of a piston valve opening into the combustion chamber. A first gas path leading out of the combustion chamber conducts gas to surface areas of the piston so as to exert pressure urging the piston valve closed. A second gas path leading out of the combustion chamber conducts gas to other surface areas of the piston so as to exert pressure urging the piston valve to open a plurality of radial exhaust ports which vent the gas out of the combustion chamber and thereby generate a sonic pulse. Periodic opening and closing of the piston valve causes a train of sonic pulses to be generated.

Abstract: This invention concerns a device for emitting shock-waves, with adjustable capacity.Such a device comprises a valve, a barrel with a seat for this valve, barrel and valve being on the same axis, and forming between them an annular combustion chamber, which can be placed in communication with the outside atmosphere by axial movement of the valve, and which comprises means of admitting the oxidant-fuel mixture, the said valve forming a differential piston, one side of which forms a mobile wall of a pressurized fluid chamber, and part of the other side of which forms a mobile wall of the combustion chamber. In this device a fixed wall of the combustion chamber contains at least two regularly spaced apertures at its perimeter, into which fit removable plugs, each of which comprises a cavity opening into the combustion chamber, and which comprise means of admitting fuel and oxidant, and ignition means. The device generates compression waves for seismic exploration.

Abstract: In seismic delineation of sedimentary section below the surface of a seismic energy propagation medium, a new use for an old article is disclosed. It includes a basic method for generating and shaping a seismic energy pulse comprising (1) generating a first energy pulse downwardly through the shortest distance to a point at the lower end of a vertical straight explosive material for forming a compressional forward portion of the seismic energy pulse, and (2) generating a second energy pulse later to form a rarefactional aft portion of the seismic energy pulse. By varying the length of the explosive material the lengths of the forward and aft portions are varied for controlling the shape of the seismic energy pulse, and by varying the position of the point of ignition of the linear explosive material, additional shaping of the seismic energy pulse results.

Abstract: A high-frequency, high-repetition gas detonator is provided which is adapted for shallow seismographic work. The detonator comprises a detonation chamber, a rigid bottom plate adapted to be coupled to the earth, and a top plate positioned over the bottom plate. A plurality of springs resiliently hold the plates together whereby the bottom plate covers a bottom vent port in the chamber when the plates engage. The bottom plate opens the chamber to the surrounding medium when the plates disengage. Fluid conduit means communicate with the interior of the chamber for supplying thereto a pressurized detonating fluid. Means are provided for detonating the fluid thereby causing the bottom plate to move downward and separate from the top plate. The compressive force of the bottom plate sends a downward seismic pulse into the underlying layers of the earth. The products of detonation from the detonation chamber are vented outside through the cavity formed between the top and bottom plates when the plates are separted.

Abstract: A pair of movable pistons are separated within an enclosed, submerged cylinder by an expansible combustion chamber. Piston rods extend from these pistons through the opposite ends of the cylinder. A pair of dish-shaped, circular plates are carried on the respective extremities of these two rods so that their convex surfaces face inwardly toward the ends of the cylinder in spaced relation. Expansion of an explosive gas mixture within the combustion chamber drives the pistons apart so as to accelerate the plates through the water, producing cavitation bubbles at their convex surfaces. Collapse of these bubbles combines efficiently to produce a single energetic acoustic pulse adapted for seismic prospecting.

Abstract: A seismic exploration system for use on ice-covered waters is disclosed. The system comprises a housing which contains equipment such as an engine, a compressor, means for boring holes in the ice, and acoustic signal generating means that can be lowered into the water through holes in the ice. The housing is sufficiently lightweight that it easily can be transported from one location to another by helicopter or other aircraft. The heat generated by the engine is sufficient to provide a comfortable working environment for personnel within said housing and helps prevent freezing of equipment located within said housing.

Abstract: An explosive charge for use under hydrostatic pressure comprising high explosive composition in a flexible plastics container closed at one end and having, at the mouth end, a shoulder and a neck defining the container opening, the opening being sealed by a closure cap which provides a central plug to support the neck against internal distortion and an outer annular skirt which supports the neck and shoulder against external distortion.

Abstract: Condensate accumulating in the combustion chamber of a marine gas exploder of the cylinder and piston type is collected by gravity flow in a sump formed in a cylinder side wall or in a face of the piston, depending upon whether the cylinder is oriented horizontally or vertically. One end of an exhaust tube is positioned adjacent the base of the sump so that gaseous combustion products flow through the sump into the exhaust tube so as to collect and remove the accumulated condensate.

Abstract: A method for decreasing the amplitude and period of bubble pulses following a primary seismic energy pulse comprises generating an expanding air bubble around a body and preventing the air bubble from contracting into the body for attenuating the sudden contraction and collapse of the air bubble, and two valve devices on a closed cylinder for carrying out the latter method resulting in minimizing bubble effect and the size of the bubble for decreasing amplitude and period of bubble oscillation for providing a clear, well-defined acoustical wave.

Abstract: This invention concerns a device for emitting mechanical waves in an external medium.This device comprises an annular or axial combustion chamber, shut by a valve, and comprising means of introducing fuel and oxidant, and an ignition system; the valve is composed of a differential piston, one side of which forms a mobile wall of a chamber containing fluid under pressure, and part of the other side of which forms a mobile wall of the combustion chamber.This device is used mainly to generate compression waves for the purpose of seismic exploration.

Abstract: The underwater gun assembly of this invention has an acceleration barrel and a firing gun. Percussion-initiatable cartridges are carried to the acceleration barrel by a stream of water. Each cartridge has an outside diameter which is nearly equal to the inside diameter of the bore in the barrel whose length is such as to allow the water pressure to optimally accelerate each cartridge in its trajectory through the barrel. The firing gun is detachably coupled to the barrel by a quick-disconnect coupling means. The detachable coupling means preferably includes a non-metallic resilient member which absorbs the shock waves from the ambient charge explosions, thereby preserving the integrity of the coupling means in respect of its detachable characteristics.

Abstract: A gas exploder consisting of a rigid cylindrical lower member and a rigid upper member telescoping therein to form a chamber in which a gas explosion can take place is supported beneath the surface of the water from a float by means of low resilience ropes connected to the bottom of the lower member so as to substantially limit its allowable downward movement. The upper member includes a piston downwardly biased within the lower member by an air spring and a hollow pedestal connected to the piston and extending freely through the float above the surface of the water to accommodate fuel, compressed air and exhaust conduits communicating with the interior of the housing. The energy of an explosion in the combustion chamber is expended primarily through rapid upward movement of the piston, which compresses the air spring and then lifts the lower member. Implosion of the resultant cavitation bubble adjacent the bottom surface of the lower member generates a pressure pulse of large peak amplitude.

Abstract: A marine acoustic seismic generator carried on the deck of a boat is coupled to a body of water in which the boat floats by a column of water in a pipe extending between the generator and the body of water. Post explosion oscillations are damped or terminated by venting the pipe of gas, either through an orifice or a valve, at a selected time, to a selected pressure, to the atmosphere or below water.

Abstract: A firing device is provided for initiation of delay type seismic charge assemblies, which comprises means for conveying and guiding the charge assemblies, in the seismic test zone, into electrical initiation contact with one of any number of available pairs of electrical conductor surfaces, insulated from the other and adapted to connect with opposite poles of an external firing current source; and means for directing the thus initiated assemblies from the initiation zone, during the delay period, for subsequent detonation.Also provided are elongated end-recessed seismic charge assemblies initiated in the above device; and seismic exploration system, and method, utilizing said device.