Abstract: A seismic pulse generator comprises a body 1 having an internal gas-pressurizable first chamber 2 adjoining a second chamber 6 for containing a fluid. A flap valve member 21 is rotatable about a pivot axis for closing a bore 24 communicating with the first chamber. A latch 22 releasably retains the flap valve member in the closed position and a gas operated piston 13 slidably moves within an associated cylinder 12. When the first chamber 2 is pressurized with gas and the flap valve member 21 is released from its closed position to uncover the bore 24, the piston 13 moves to cause communication between the chambers 2,6 and generation of a shock wave in the second chamber. The second chamber has outlet means 7 to permit a pulse of energy to be transmitted from the second chamber in response to the shock wave generated in the second chamber.

Abstract: A towed streamer having a buoyant core, a data bearer layer surrounding the buoyant core, an inner jacket layer formed of a resilient material surrounding the data bearer layer, and an outer jacket layer surrounding the inner jacket layer, wherein a series of longitudinally positioned strength members are embedded in the inner jacket layer to extend along the streamer to transmit tension along the streamer while the streamer is held in the inner jacket layer.

Abstract: A fastening device for fixing seismic circular devices is designed with a rigid, split, annular clamp (4) with an open void facing the seismic device (1) for insertion of at least one shock absorbing member (7) in the void. Such a clamp (4) is provided in the region of the device which is most subjected to strain, where a concentric securing ring (8) is also mounted, about which the clamp is fitted with a shock absorbing member (7) on each side of the ring. One more such clamp is provided on the seismic device (1) in order to distribute the load. This arrangement is especially suitable for use in connection with seismic airguns which are to be fixed at predetermined mutual distances in a frame structure (2).

Abstract: The invention is an apparatus for distributing a lubricant to the air guns in a single airline seismic air gun subarray which utilizes an air-lubricant mixture to operate and lubricate the air guns in the subarray. The air-lubricant mixture from the single airline is supplied to each air gun through a separate adapter and a cut-off valve. The lubricant tends to accumulate near the first several air guns, which wind up using most of the lubricant contained in the mixture while leaving no or very little lubricant for the remaining air guns. To prevent this uneven distribution of the lubricant, a lubricant metering device is placed in certain adapters to control the amount of the lubricant supplied to their associated air guns. Using the lubricant metering device to control the lubricant supply to the air guns in a subarray ensures that all the air guns receive adequate lubricant supply.

Abstract: A compact, marine acoustical source is disclosed. More specifically, the present invention relates to a marine acoustical source capable of producing a strong primary pulse while substantially suppressing or eliminating undesired secondary pulses derivative from said primary pulse.

Abstract: A dual shuttle air gun for generating maximum acoustic output for seismic testing having a housing with an air chamber formed therein and a chamber opening that opens 360 degrees around the periphery of the body is disclosed. The two shuttles are positioned around the housing axially displaced from each other, but close enough to allow the end faces of each shuttle to come into close proximity with each other. When the air gun is fired by the activation of a solenoid, compressed air flows into a firing chamber formed between the first shuttle and the housing causing the first shuttle to begin opening. When the first shuttle moves, the end faces of the two shuttles are exposed to the compressed air from the primary chamber. This causes the two shuttles to rapidly move away from each other providing for very quick release of the stored compressed air. When the solenoid is deactivated, the two shuttles are forced back into a prefire condition over the 360 degree opening.

Abstract: Method and apparatus for converting tube waves into body waves downhole for seismic exploration are disclosed, comprising a rotary valve tube wave source for producing swept frequency tube waves that are injected into a tubing or wellbore. The tube waves are converted to body waves by an elongate tube wave converter located at a selected position downhole. The tube wave converter comprises an elongate body that preferably substantially fills the wellbore or tubing and has a preferred shape in order to convert efficiently the tube waves to body waves at the selected position downhole.

Abstract: The present invention is directed to a method of modifying or reshaping the acoustical signature created by the explosive, underwater release of a highly pressurized gas. More specifically, the present invention is directed at a method for modifying the asymmetric and cuspate nature of the acoustical signature derivative from the generation of a primary pulse so as to allow for the beneficial superimposition of a second wavelet of opposite phase.

Abstract: An apparatus for positioning a plurality of marine seismic sources in an array. The marine seismic sources are retained in retaining means which are mounted to a frame so that each source is separated from the nearest other source in the array by a predetermined distance. Shock absorbing means are mounted in the frame intermediate each of the retaining means and each other retaining means mounted to the frame.

Abstract: An underwater acoustic generator comprising a tapered solid positioned in a luid flow to produce a cavitation void. A source of gas supplies the void with gas to produce a resonant gas bubble.

Abstract: A firing system for marine seismic sources 14 grouped and fired in subarrays 18. Each source 14 is provided with a firing circuit 30 including an energy storage device, such as a storage capacitor 32, adapted to pass firing current through the source actuator 24 in response to receiving a low power trigger signal from a source control system 28 located on the ship 16 from which the seismic survey is conducted. The firing circuit 30 corresponding to each source 14 is situated proximate the source 14. An umbilical 20 extends between the control system 28 and each subarray 18. The umbilical 20 includes a trigger signal conductor corresponding to each source, a charging conductor to which the storage capacitors of each firing circuit 30 are connected in parallel and a ground conductor.

Abstract: A towable marine seismic source apparatus for producing a high resolution seismic signal at relatively shallow depths for engineering surveys is disclosed. The apparatus support frame operably mounts a plurality of eight identical chambered air guns in a 2.times.4.times.2 configuration to provide a tapered, heavy centered point source. The cylindrical air guns are positioned in a horizontal orientation at a predetermined depth of 1 to 3 meters and are synchronized to fire substantially simultaneously to achieve maximum peak energy output. Two chamber sizes of individual air guns (4 cu. in. & 10 cu. in.) are in a desired range and may be preferably employed in the array configuration to produce the seismic signal having distinct signature characteristics.

Abstract: The novel method substantially reduces the pressure pulse, generated by a first radial motion of a body of water, by changing the radial motion into axial motion. The change from radial motion into axial motion is produced by generating a second radial motion of opposite phase within the body of water.The method can be used to substantially reduce the pressure pulse, generated by the implosion of a body of water, by generating an explosion in the body of water. It can also substantially reduce the pressure pulse generated by an explosion within a body of water, by generating an implosion of the body of water. The method can further be used to generate within a body of water an impulsive acoustic signal by sequentially generating within the body of water a first explosion and a second explosion. The apparatus comprises a signal chamber which contains a first charge of gas. A normally-closed valve maintains the signal chamber closed and has a discharge port into the water.

Abstract: The present invention comprises an apparatus and method for producing a high resolution acoustic signal from a single point source while achieving a commercially acceptable secondary bubble suppression. More specifically, the present invention comprises first and second explosive generators which sequentially create two explosions or one explosion and injection, within the body of water; said first explosion producing within the body of water a powerful acoustic pulse in an expanding cavity of very low pressure, said second explosion or injection establishing hydrostatic pressure within the cavity about the same time the volume of the cavity reaches its maximum volume, thereby substantially reducing the secondary pressure pulses.

Abstract: The novel method substantially reduces the pressure pulse, generated by a first radial motion of a body of water, by changing the radial motion into axial action. The change from radial motion into axial motion is produced by generating a second radial motion of opposite phase within the body of water.The method can be used to substantially reduce the pressure pulse, generated by the implosion of a body of water, by generating an explosion in the body of water. It can also substantially reduce the pressure pulse generated by an explosion within a body of water, by generating an implosion of the body of water. The method can further be used to generate within a body of water an impulsive acoustic signal by sequentially generating within the body of water a first explosion and a second explosion. The apparatus comprises a signal chamber which contains a first charge of gas. A normally-closed valve maintains the signal chamber closed and has a discharge port into the water.

Abstract: In order to accumulate data from which the signature of an array of n interacting seismic sources 21 to 27, for instance marine seismic sources in the form of air guns, can be determined, 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. Data from the measured pressure wave is stored for subsequent processing 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: The present invention comprises a multi-barrel seismic source air gun module for use in a marine environment, preferably comprising a plurality of air gun barrels symmetrically disposed in a single plane about and rigidly secured to a control head containing means for actuating said barrels.

Abstract: A marine seismic array wherein each air gun in the array is provided with an air supply valve that can be closed remotely to inactivate a particular air gun and then reopened upon command to reactivate the gun without retrieving the array. The valve is comprised of a housing having a ball valve therein which is rotated between an open and closed position by a reversible, electric motor in the housing upon the flowing of current to the motor in either a first direction or in an opposite direction. Limit means are provided in the housing to stop the motor when the ball valve rotates to either a full open or a full closed position.

Abstract: An apparatus for producing acoustic waves in water through sudden ejection of liquid mass from a tubular main housing. A first shuttle and 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 ports in the housing. A calibrated control element for providing the proper pressures to the pneumatically-operated valve ensures proper movement of the shuttles.

Abstract: The disclosure relates to a solenoid valve for an air gun which substantially increases the rate at which maximum air flow is achieved. The new valve structure includes a coil actuated plunger, which is preferably solid and formed of a magnetically permeable material and closes an annular 360 degree port opening between the valve inlet and valve outlet when in the unactuated state. This plunger position is maintained by a biasing spring which forces the forward annular sharp plunger edge against a face seal in the nose of the valve, thereby sealing the valve input port from its output port. Upon actuation of the solenoid valve coil, the plunger is moved against the bias of the spring very rapidly, thereby speedily uncovering the channel between inlet and outlet and permitting rapid 360 degree communication between the inlet and outlet to permit maximum air flow therebetween and out of the outlet port.

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: 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 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: In the art of acoustic well sounding a gas-gun for the sudden discharge of a measured quantity of compressed gas, comprised of two chambers, viz. a discharge chamber closed at one end by a poppet, and on the opposite end by a power-head, the latter a cylinder including a sealed piston, with the poppet connected by sealed piston rod penetrating the cylinder head, and terminated at the piston. The entire assembly to be so proportioned that regardless of the position of the piston of gap remains between the piston and the cylinder-head penetrated by the piston rod. Means for connecting this gap to the inside of the discharge chamber through a check valve permits gas flow from the discharge chamber to the gap, but no in the reverse direction, and means for venting the gap to the atmosphere. A passage from the opposite side of the piston to the axial outlet of the discharge chamber, a spring or a positive locking device for pressing the poppet against the valve seat.

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: A high ambient liquid pressure-resistant electrical connector is shown with an airgun having a solenoid actuated valve mounted on the airgun. A multi-conductor electrical cable is connected by this pressure-resistant connector to a plurality of terminals of the solenoid valve for protecting from ambient liquid the terminals and the adjacent portions of the conductors. This pressure-resistant electrical connector includes a connector housing having an upper end and a lower end, with the lower end of the housing being mounted to the airgun. The connector housing has a fluid sealant chamber for enclosing the electrical terminals and adjacent portions of the conductors connected to the terminals and includes at least one barrier for engaging the cable to protect against ambient liquid seeping past the barrier to the electrical terminals. The connector housing defines a cylindrical space carrying a spring-loaded piston.

Abstract: A float for use in seismic surveys of the sea bed supports a plurality of seismic pulse transmitters (6) which are suspended on lines (7) beneath the float (1). At a distance from the front end of the float (1), on one sidewall thereof, a fastening device for a towing cable and a lead-in for control lines and lines for supplying operating medium to the pulse transmitters are provided. These lines and cables are gathered in a common line (3) which extends behind the tow ship. The line (3), at a distance away from the float (1), is connected to a line (4) which leads to a length-regulating device (12) inside the front section of the float. The float is also provided with at least one motor (10) with a drive shaft (9) leading to hoisting drums (8) for the lines (7) to the respective seismic pulse transmitters (6). Both the motors (10, 12) and the seismic pulse transmitters (6) are connected to the pneumatic supply line.

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 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 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 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 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 seismic acoustic source for generating acoustic pulses in both solid rock and sedimentary layers on land and in both water, rock and sedimentary layers at sea comprises: two chambers; a high pressure chamber and a low pressure chamber communicating but separated from each other by, for example, a first diaphragm, the low pressure chamber being closed by, for example, a second diaphragm. The high pressure chamber contains gas e.g. helium at high pressure whereas low pressure chamber contains a gas such as carbon dioxide at a lower pressure. The pulse is generated by bursting the diaphragm separating the two chambers whereupon the shock wave generated in the carbon dioxide then travels to the other end of the low pressure chamber and leaves by over-pressure behind the shock bursting the second diaphragm. Repetitive operation may be achieved by replacing the first diaphragm with a shock wave valve and the second with operable valve means such as an iris diaphragm or full-bore gate valve.

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 far-field pressure signature of an air-gun array is derived from near-field measurements. An array of air guns is deployed in the water at a desired depth. A hydrophone is suspended in the middle of the array at the same depth so that the guns are equidistant from the hydrophone. The lateral spacing between the guns and the sensor is much less than the water depth of the guns. Having fired the guns, the ghost reflection amplitude in the near field will be much less than the amplitude of the direct arrivals and can be ignored. The far-field signature is determined by inverting the observed pressure signature, delaying it in proportion to array depth and adding the inverted, delayed signature back to the original signature.

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: In the art of acoustic well sounding a gas-gun for the sudden discharge of a measured quantity of compressed gas, comprised of two chambers, viz. a discharge chamber closed at one end by a poppet, and on the opposite end by a power-head, the latter a cylinder including a sealed piston, with the poppet connected by sealed piston rod penetrating the cylinder head, and terminated at the piston. The entire assembly to be so proportioned that regardless of the position of the piston a gap remains between the piston and the cylinder-head penetrated by the piston rod. Means for connecting this gap to the inside of the discharge chamber through a check valve permits gas flow from the discharge chamber to the gap, but not in the reverse direction, and means for venting the gap to the atmosphere. A passage from the opposite side of the piston to the axial outlet of the discharge chamber, a spring or a positive locking device for pressing the poppet against the valve seat.

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: 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 air gun is mounted in a reaction mass having an impulse-transmitting ground-contact plate movably mounted below the mass. This mass is in face-to-face contact with the plate over the major portion of the entire upper surface of the contact plate. Confined liquid is not employed. The air gun is charged with pressurized gas and fired, discharging the pressurized gas into the narrow horizontal interface region between reaction mass and plate. Rapid expansion of the discharged gas between mass and plate causes an intensely powerful seismic impulse to be transmitted into the earth. The air gun has a firing chamber for holding a charge of pressurized gas, a movable shuttle for suddenly discharging the pressurized gas, including upper and lower pistons with a hollow member connecting these pistons. A pedestal assembly carrying said shuttle is mounted from above to the reaction mass and extends down into the hollow shuttle member.

Abstract: A plurality of control station, watertight, submerged junction boxes are towed at spaced positions located along an airgun array, each junction box for including a microprocessor and data storage transmission capability, and airgun firing circuits to control predetermined airguns. The electrical cable for the array and the air supply lines, as well as the airguns to be controlled, are detachably coupled to respective junction boxes. Thus, the number of airguns in the towed array can be changed quickly and conveniently by coupling or uncoupling junction boxes and the associated airguns. A protective hose sheath extends between successive junction boxes and this hose sheath contains power lines and a communication bus, detachably connected to terminals in successive junction boxes. This hose sheath and interiors of junction boxes are pressurized with low pressure air during towing for excluding water in the event of a leak.

Abstract: A method and system are provided for well velocity shooting and vertical seismic profiling utilizing mobile seismic land sources for transmitting powerful seismic energy impulses into the earth. A plurality of nesting pairs of tanks are transported on a single vehicle to a well site where the tanks are unloaded and arranged in a suitable array, for example, in a linear array or uniformly spaced around the mouth of the well. The tanks each have a displaceable end portion serving as a diaphragm placed in contact with the ground near the well. Then the tanks are filled with a noncompressible liquid. The total effective mass of the liquid may be increased by adding density-increasing materials thereto. Air guns are suspended in the tanks submerged in the liquid therein. The air guns are fired in a predetermined manner, abruptly releasing pressurized gas into the liquid contained in the tanks for providing powerful seismic impulses which are transmitted into the ground by the displaceable diaphragms.

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.