Abstract: A process and a device for hydrodynamic sound pulse generation in a liquid, n particular for sound pulse generation at sea for marine geophysics measurements.

Abstract: An uncomplicated, easy to operate, relatively inexpensive, compact and powerful acoustical source hydro gun for use in a liquid environment is particularly effective in a multiple array for marine life management. The powerful output, compactness and non-complex features of this hydro gun enable its advantageous use as a seismic energy source for high resolution marine seismic exploration and for seismic exploration when lowered down into a well in the earth containing liquid. A cylinder containing a free-moving piston has water discharge ports near one end for admitting water when the hydro gun is immersed in water and for discharging water when the hydro gun is activated by a solenoid valve. The solenoid valve is mounted on a cylinder head block containing a small annular high pressure firing chamber charged with pressurized gas and closed by the solenoid valve.

Abstract: The method and apparatus for generating seismic vibrations in a liquid includes an electronically controlled, hydraulically powered generator that includes a piston assembly reciprocally mounted on a cylindrical post in a generator housing. The control apparatus includes a control valve that is located very close to the piston assembly thereby reducing the volume of the passageways extending to the piston assembly so that the cyclic rate of the piston assembly can be very rigid and can be changed accurately and quickly. An extended life is provided by releasing the high pressure fluid driving the piston assembly prior to impact between the piston assembly and the post and by providing a trapped volume of fluid in the chamber to damp the movement of the piston assembly toward the post.

Abstract: A long-life, low-maintenance air gun/hydro gun includes a one-piece, integral shuttle having an unusually long hollow shank with a firing piston whose configuration is the mirror image of the operating piston, except for the slightly smaller diameter "D" of the firing piston. The shank length L is at least 2.5 times D, and the whole shuttle is guided by this shank sliding within a shaft seal and bearing assembly. By virtue of this guidance, the perimeters of the operating and firing pistons are always kept slightly spaced from their respective associated cylinder walls for eliminating contact of these pistons with their cylinder walls for advantageously dramatically increasing the total number of operating firing cycles which can be accumulated in use before the need for replacing any worn parts, except for the operating and firing seals which are inexpensive. Thus, this air/hydro gun offers a low-maintenance feature.

Abstract: The volumetric capacity of the firing chamber of an air gun is discretely quantized by mounting unit-volume inserts interiorly of the firing chamber.

Abstract: A dual chamber seismic air gun which discharges both chambers simultaneously to counterbalance the reactive forces generated by the discharges. The chambers are symmetrical within the housing of the gun so that the movement of the internal parts during operation also counterbalance each other. The gun is mounted coaxially on the air supply of a seismic array to provide a good profile for towing.

Abstract: A transmission from a hydroacoustic source, especially for underwater geophysical exploration, is generated in accordance with two binary codes (provided by two pulse trains or sequences having two levels and which provide a spectrum of harmonically related components). One of these codes has one more or one less harmonic component than the other. The transmission is provided with a frequency spectrum which extends between an upper and lower frequency limit by sweeping the pulse trains over an octave (2:1) frequency range, far shorter than the range of the spectrum, and utilizing one of the codes and then the other of the codes during the sweep. The spectrum of the transmission extends between two arbitrary frequencies which need not be harmonically related, notwithstanding that the sweep is limited to an octave in frequency range.

Abstract: A plurality of submerged control station junction boxes each include a microprocessor having data storage and transmission capability, airgun firing and related electronic circuits to control a predetermined airgun or airgun groups. These junction boxes are towed at spaced positions along an airgun array. An electrical cable and sections of high pressure air supply line are detachably coupled to each junction box. The predetermined airguns to be controlled by a junction box are detachably coupled thereto. Thus, the number of airguns in the towed array can be changed by coupling or uncoupling junction boxes and the associated airguns controlled by them. The junction boxes are automatically cooled on shipboard by increasing low pressure air until a relief valve opens for establishing a continuous cooling flow of low pressure through a protective hose sheath and the junction boxes.

Abstract: An airgun impulsive energy source has an elongated shaft bearing surrounding the shaft of the reciprocatable shuttle for guiding the shuttle and preventing its operating or firing pistons from contacting their respective cylinder walls. The illustrative embodiment of this airgun is proportioned to be self-firing with a fast repitition rate. This airgun has an elongated cylindrical housing with discharge ports in a cylindrical wall positioned between the operating and firing chambers. The shuttle-guiding shaft bearing is positioned in the cylindrical housing between the ports and an operating chamber. This shaft-guiding bearing has a length which is more than 1.

Abstract: A water gun seismic source for use in underwater environments has a sleeve valve (100) for opening a jet aperture (37, 101) to enable jets of pressurized water to be emitted for the generation of a seismic signal. The water is pressurized by a drive piston (3) which is reciprocated to a cocked position for pressurizing the water for the jets. A compressed air operated cocking mechanism (4, 7, 8, 76 or 110-199 or 200-260) is coupled to the piston for cocking it. The cocking mechanism may utilize cocking piston (7) slideable on a shaft (4) connected to the drive piston (3) which cocking piston is returned to a position where any load due to such cocking piston is decoupled from the shaft. The sleeve valve (100) may be biased to close the jet aperture ports (101) by compressed air and opened with high timing resolution when the pressurized water held back by the sleeve valve is applied to actuate it (via 40, 41, 50 & 43).

Abstract: An impact tool for linearly accelerating a mass such as in a jack hammer. The tool includes first and second members respectively mounted in sealing relationships in first and second outlets of a chamber. The chamber is initially pressurized with a first quantity of gas which remains constant during the normal operation of the tool. To begin a cycle, the first member is moved toward the second member to sealingly engage the end portions thereof and entrap a first volume of gas therebetween. The volume of the entrapped gas is then reduced by continuing to move the first member. This raises the pressure of the entrapped gas and opens a one-way check valve to place the entrapped gas in fluid communication with the gas in the surrounding chamber. Forward movement of the first member is then stopped which again seats the check valve wherein movement of the first member is reversed so that it moves away from the second member.

Abstract: A land seismic energy source is provided having a rigid dome-shaped bell containing a substantially imcompressible liquid and an airgun for abruptly releasing pressurized gas into the liquid for generating powerful seismic impulses. The bell has a lower rim with a metal pan positioned below the rim for engaging the surface of the earth below the bell, and it is mounted for upward and downward movement relative to the bell. A resilient, flexible elastomeric diaphragm is mounted on the rim of the bell and extends across the bottom of the bell for retaining the liquid in the bell.

Abstract: The novel method substantially reduces the pressure pulse generated by an implosion of a cavity within a body of water by aborting the implosion. The abortion of the implosion is produced by generating within the cavity an explosion at the instant that this cavity attains its maximum volume.The method can also be used to generate within a body of water an impulsive acoustic signal by generating a first explosion within the body of water to produce therein a powerful pressure pulse and a cavity of very low pressure, and then generating a second explosion within the cavity so as to establish hydrostatic pressure inside the cavity while the volume of the cavity remains within a few percent of its maximum volume.

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: An underwater vibrator is specifically adapted for generating a shear wave in a seabed and includes a frame; locomotion apparatus attached to the frame for moving the vibrator over the seabed; and cable means connected between a surface support vessel and the vibrator. The vibrator also includes buoyancy and apparatus for selectively controlling the buoyancy along with apparatus for selectively engaging the seabed with the vibrator. Apparatus is also carried by the vibrator for viewing the location of the vibrator under the water which includes lights and television equipment.

Abstract: A bi-planar pontoon paravane is towed by a marine vessel and controls the depth and position of a towed seismic source array. The bi-planar pontoon paravane is made up of a buoyant bridge with right and left wings attached to the long sides of the bridge, the wings projecting into the water and, in concert, providing a side force. The paravane is towed by a tow line connected to an adjustable bridle which in turn is connected to the paravane. Remote adjustment of the bridle is provided by an hydraulic valve on the vessel controlling an hydraulic motor and gear arrangement on the paravane to adjust the bridle. Adjustment of the bridle adjusts the angle of attack of the paravane. The paravane provides a housing formed below the bridge and between the two wings for housing the seismic source array. A boom on the vessel is attached to the seismic source array, through the bridge, when the assembly is to be placed in or removed from the water.

Abstract: A dual chamber seismic air gun which discharges both chambers simultaneously to counterbalance the reactive forces generated by the discharges. The chambers are symmetrical within the housing of the gun so that the movement of the internal parts during operation also counterbalance each other. The gun is mounted coaxially on the air supply of a seismic array to provide a good profile for towing.

Abstract: A seismic source is disclosed which is particularly useful for generating horizontally polarized shear waves in the earth for seismic surveying. It comprises an elongated, hollow, substantially vertical cylinder having an earth-contacting pad pivotally mounted to its lower end by a horizontal pivot shaft extending parallel with the front-to-back centerline of a transport vehicle. The lower surface of this large rigid pad contains multiple, blade-like teeth extending parallel with the pivot shaft for gripping the earth's surface for transmitting powerful horizontally polarized shear stress impulses into the earth. The cylinder contains a slidable piston-like reaction mass. The bottom of the cylinder is a strong upwardly diverging conical surface serving to focus and direct upwardly the discharge blast from each port of an air gun extending horizontally and with the axis of the air gun being oriented parallel with the pivot axis and being located a short distance above the pivot shaft.

Abstract: A seismic air gun has a passage between the stem of its shuttle and a baffle, whereby ambient pressure can reach the back of the operating piston. The gun is fired by dumping a small quantity of pressure air from the operating chamber via a solenoid valve to the ambient surroundings. The firing seal is a lip seal. The shuttle is of unitary construction, while the baffle is diametrically split.

Abstract: A marine air gun is advantageously converted into a hydro gun by substitution of two clamp rings and by convenient addition of various parts, allowing normal air gun firing by triggering with usual solenoid valve. In a presently preferred embodiment, a novel firing chamber is also substituted, providing outwardly-facing piston rings and cylinder encircling this chamber. A special clamp is substituted for that which normally secures operating chamber to firing chamber. An outer-cylinder-defining housing is concentric around the firing chamber, with an annular piston sliding in the annular cylinder space defined intermediate the firing chamber and the new outer housing. This annular piston is propelled by the air blast, suddenly ejecting water slugs from ports in the new outer housing. Also added is a pressure-controlled air-vent valve, responsive to air pressure coupled through passages in an adapter mounted between solenoid valve and air gun.

Abstract: An underwater vibrator apparatus for generating a shear wave into the consolidated seabed has a housing, a horizontally mounted mass attached to said housing for movement along an axis substantially parallel to the surface of the earth and hydraulic apparatus for oscillating the mass along the axis. Substantially all of the vibrator housing comprises a sidewall and a bottom. The sidewalls and bottom form a wedge-shaped surface means with an angled surface of the wedge-shaped surface transverse to the movement of the mass, such that as the mass oscillates the underwater vibrator against the consolidated bottom, the vibrator will settle into the bottom. The vibrator will, however, maintain contact with the bottom even when the consolidated bottom is yieldable under vibrated weight.

Abstract: An acoustic energy source or gun for use in an aqueous environment such as in a borehole, a well, or in open water. The apparatus, when lowered into a water occupied borehole or the like, functions to create a series of acoustic impulses without forming bubbles, as a result of the water rapidly infilling an implosion cylinder or chamber. A piston rod assembly is reciprocally mounted in each acoustic chamber and is actuated by a power source to trigger the desired sound creating series of impulses.

Abstract: An assembly for use in seismic surveys of the sea bed is towed behind a vessel and comprises groups of seismic signal transmitters which are towed through the water, being suspended from float buoys which are combined to form one body which may be formed as a sleeve having limited flexibility. The body is formed with a head member shaped for reducing resistance to the water, and connected to a coupling point for a tow wire to the vessel, which point lies forward of the head member and at the same depth as the transmitters.

Abstract: A device for generating acoustic pulses by driving suddenly into a body lowered in a well a piston having a face in contact with the liquid contained in the well and adapted for sliding inside said body. The device comprises a valve securely fixed to the piston, a second piston and a hydraulic system disposed completely in the body and comprising principally a pump, electro-valves, an equalizing cylinder, a low pressure reservoir and supply circuits, for moving the valve and the piston to a set position and for immobilizing it intermittently.

Abstract: An apparatus and method for generating a shock wave in water comprising a housing capable of containing compressed gas, attachment means fastened to the housing by which the apparatus is oriented in a selected positioned and exhaust means in the housing positioned to release compressed gas in directions other than substantially upward. In a preferred embodiment, a commercially available compressed air gun is modified by blinding off the uppermost exhaust ports.

Abstract: The invention is a multi-port, multi-chamber, tuned, air-powered subsea seismic source. It is suitable for producing a seismic wave in a subsea environment during seismic prospecting. Interconnected pressurized chambers are formed between plates located on a movable shuttle and cylinder walls extending inward from the source housing. The source is fired by moving the shuttle through a stroke and allowing the pressurized air within the air chambers to exit through ports into the surrounding water. A unique seal arrangement in also shown.

Abstract: The invention relates to a method of determining the location in the earth of sub-surface boundaries and/or the acoustic properties of sub-surface features substantially in the absence of the far field source wavelet and noise and with errors due to reflections of sound waves from the water being substantially compensated for. The invention uses point sound sources or arrays thereof at a first depth and then scales the energy, pressure and spacing of a similar source at a second depth to provide data which is used to obtain a seismic record.

Abstract: Mounting structure for a marine seismic vibrator comprising at least three acoustic isolators equally spaced apart about an upper housing of the vibrator. Each of the isolators comprises a pair of spaced mounting pads mechanically secured to the housing. A U-shaped bracket having a base and depending spaced leg portions is attached to the mounting pads by way of a low-pass acoustic filter. A rectangular shaped bracket has a base, a top and a pair of spaced vertical sidewalls. The rectangular shaped bracket is located between the spaced leg portions of the U-shaped bracket and a resilient means is mounted between the bases of the U-shaped bracket and the rectangular bracket to provide a high-pass acoustic filter. Means mechanically connected to the top of the rectangular brackets to the tops of the mechanical brackets secure all the isolators to a common point at the center of the housing.

Abstract: The invention relates to a compact tunable subsea seismic source. The source has multiple seismic radiating plates placed symmetrically about a central housing which contains a hydraulic actuating system. The source is towed to optimize the amount of energy applied to the surrounding water.

Abstract: A seismic source drives one or more jets of high velocity water into an underwater environment and then terminates the jets by means of a valve member, the motion of which is controlled to obtain precisely timed high energy seismic pulses to provide reflected signals from which high resolution seismograms may be obtained when the signals are processed.

Abstract: Apparatus for forming a downwardly directed beam of acoustic wave energy in a body of water, comprising a source of acoustic wave energy such as a water gun, supported at a selected depth in the body of water. Means are provided above and around the source in the form of a series of concentric circular tubes of selected diameters and spacing so that the enveloping surface is a paraboloid. A large number of small perforations are spaced along these horizontal tubes through which compressed gas, which is supplied to the tubes, can escape and form spaced rising columns with small gas bubbles in the volume of water above the paraboloid. The highly reflecting contact surface between the water within the paraboloid and the gas-water mixture above the paraboloid causes downward reflection of seismic energy from the source in the form of plain waves of seismic energy.

Abstract: A seismic energy source air gun has a body with an air chamber formed therein that opens 360 degrees around the periphery of the body. A sleeve-type shuttle covers the opening in a pre-fire condition. When the air gun is fired, the shuttle moves rapidly away from the opening providing a large area for compressed air held in the chamber to escape. This very quick release maximizes the acoustic output. The movement of the shuttle is ultimately controlled by a solenoid which, when activated, causes the shuttle to move away from the 360 degree opening and when deactivated permits the shuttle to move back into the pre-fire position over the 360 degree opening.

Abstract: A moving seismic source system for the use in water-covered areas comprising a conventional source and streamer cable means with multiple receiver, and additionally includes between the source and receivers a volume of the body of water containing a small percentage of free gas to form a gas-water mixture. The volume of gas-water mixture is of select size and shape to form an interface with the gas-free water to form, for example, a paraboloid which acts to reflect and attenuate acoustic waves that impinge on the interface and so minimizes extraneous seismic noise.

Abstract: An acoustic source for seismic exploration in a water environment consists of an elongated cylindrical housing, closed at both ends and containing laterally disposed exhaust ports. A reciprocable piston and piston follower are slidably mounted within the housing for reciprocal movement. Pressurized hydraulic fluid is admitted to one end of the housing, forcing the piston follower to contact the piston and move towards the opposite end of the housing. A pneumatic latching device retains the piston proximate opposite cylinder end and pressurizes the system. The hydraulic fluid is drained, allowing the piston follower to return to its original position. During the return trip of the piston follower, water is ingested through the exhaust ports to the chamber between the piston and the piston follower. A triggering mechanism then releases the piston that is accelerated towards the piston follower, to impulsively expel the contained water. The ejected water creates a momentary cavity in the surrounding water.

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 disclosed device is a marine seismic source which produces a varying FM signal often in the 10-100 Hertz region of the spectrum. The seismic source uses stiff oscillating radiators to create a signal in the water. These radiators are actuated by hydraulic cylinders which are in hydraulic communication with hydraulic or oleo-pneumatic variable devices acting as springs with a variable spring rate. Variation of the spring rate as a function of the frequency permits the device to be tuned for maximum power output.

Abstract: The disclosed device is a marine seismic source which emits a constantly varying FM signal in the 10 to 100 H.sub.z range. The seismic source utilizes an adjustable length cantilever spring rotatably attached to stiff acoustic radiators, which create a signal in the water. Varying the length of the cantilever spring as a function of the frequency will permit the device to be continuously tuned for maximum power output.

Abstract: An underwater sound generator comprising dual opposed pistons in a housing. Dynamic seal assemblies of flexible waterproof material are compressed against the peripheries of the pistons and the housing and form a watertight seal that allows axial motion. Controllers regulate the delivery of pressurized hydraulic fluid to hydraulic actuators which drive the axial motion of the pistons according to a predetermined variation.

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: The present invention relates to a method for initiating an underwater implosive seismic source which comprises the steps of: measuring the instantaneous pressure at the location of the source; determining, from this measured pressure, the bubble period separating the firing signal from the implosion peak of the shock wave; and initiating the source with a delay or advance of a value equal to the difference between the bubble period corresponding to the instantaneous pressure and that corresponding to the mean pressure. The invention also provides a device for carrying out this method which device comprises; means for measuring the instantaneous pressure in the neighborhood of the source; comparator means (C5) for comparing this pressure with a mean value; and time delay means (C3, C4) for delaying a firing signal (S1) by a value which is a function of the result of this comparison.

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: The disclosed device is a marine seismic source which produces a varying FM signal in the low end of the acoustic spectrum. The seismic source uses stiff oscillating radiators to create a signal in the water. These radiators are attached to devices acting as springs with a variable spring rate. Variation of the spring rate as a function of the frequency permits the device to be tuned for maximum power output.

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: An underwater shear wave vibrator apparatus has a housing with a vibratory generating system mounted inside the housing for generating a force along an axis substantially parallel to the underwater seabed surface. A coupling apparatus which has an attachment surface and an underside surface for engaging the seabed is connected through a pivotal arm to the housing. A hydraulic apparatus is used for positioning the seabed engaging apparatus normal to the force axis of the vibratory generating apparatus by movement about the pivotal attachment so as to maintain contact of the seabed engaging apparatus with the seabed as the vibratory generating apparatus applies force against the seabed. Apparatus is also included for maintaining orientation of the underside surface of the positioning apparatus as the positioning apparatus moves the seabed engaging means.

Abstract: An acoustic source is provided where a high pressure fluid is used to positively control the period an exhaust valve is open. High pressure fluid is introduced to the control chamber at a predetermined instant after the exhaust valve or shuttle has been opened. This results in conservation of air used to fire the acoustic source and also to achieve a desired signature.