Abstract: A downhole seismic signal source (vibrational or impulsive) capable of producing a signal of sufficiently high energy to permit the tool to be used in a deep wellbore (exceeding 4000 feet). A piston rod having two pistons reciprocates in an elongated cylindrical housing. An electrohydraulic valve controls the flow of hydraulic fluid to opposite sides of a first piston to control the piston rod's vertical movement. The second piston is positioned between a fluidic spring which balances the pressure of the wellbore fluid and a reservoir of hydraulic fluid which inflates a flexible bladder to produce the seismic signal in the wellbore fluid.

Abstract: An improved inclinable vibratory seismic source arranged to be vehicle mounted including a base plate mounted for movement relative to the vehicle frame and for engagement with the ground. Hydraulic cylinders are provided for raising and lowering the base plate. A shaft is connected to the base plate by a U-Joint and has a vibratory mass located thereon. Also, located on the shaft is a reaction mass that is resiliently coupled to the vibratory mass and tuned so that the reaction mass remains virtually vibration free. Control apparatus is connected to the reaction mass to position the shaft and vibratory mass at a preselected azimuth and inclination.

Abstract: A seismic energy source provides a bias pressure and oscillating pressure force on a piston mounted transversely to the major axis of the well bore and in pressure contact with the wall of the well bore. A seismographic energy wave is generated in the surrounding earth by oscillating the pressure of the piston against the well wall. This apparatus uses the pressure of ambient fluid in the well bore to reduce the power required to provide pressure contact and to oscillate the piston against the wall.

Abstract: A system is provided for transmitting energy to an apparatus, such as a pulsed or vibratory seismic source, lowered inside a well or drill hole. It includes a structure anchorable in a well, mobile means whose linear displacement with respect to the anchorable structure causes the creation of energy and means for accumulating the energy created, a rigid column connected to said mobile means and drive means disposed outside the well for moving the rigid column linearly. The mobile means and the accumulation means may be formed by a weight and a device for raising this latter or else by a hydraulic system including a linear pump.

Abstract: Vibrator apparatus having adjustable cylinder volume by means of a continuously adjustable end sleeve that varies the axial limit of the cylinder. A reaction mass with an axial cylinder bore reciprocates on a double rod piston. Frist and second end sleeves define the cylinder volume and one end sleeve is threaded and axially translatable relative to the piston to vary volume while a position sensing device continually maintains centering of the piston in the cylinder.

Abstract: Apparatus for generating seismic waves including an upstanding hollow cylindrical housing within which an impact piston latched in a cocked position is adapted to be propelled downwardly by high pressure expanding gas in the confined chamber above it within the housing so as to strike a target plate resting on the ground adjacent the lower end of the housing. After each blow against the target, the piston is retracted upwardly by means of hydraulic cylinders which recompress the gas in the chamber to its original pressure. Since there is no need for recharging the pressure chamber after each shot, economical rapid cycle operation is facilitated.

Abstract: A seismic signal generator with a self-adjusting footprint base plate. A signal generator for use on paved or other hard surfaces, has a pair of tread members (preferably urethane) that are laterally slidable with respect to the reaction mass. The tread members are biased outwardly away from the reaction mass. Should slippage from the point of initial placement occur during signal generation, the biasing force will continue to move the tread members outwardly to a more stable position, thereby achieving optimum intimate contact between the generator and the surface of the ground maximizing signal transfer into and through that surface.

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 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: A method and apparatus for downhole source generation of seismic waves of adjustable frequency by isolating a volume of liquid in a bore hole and cyclically varying the volume by a hydraulically operated transforming piston which varies the pressure of the volume thereby displacing the surrounding strata to generate waves.

Abstract: A vibratory seismic surface source includes a single vibrating mass, the energy of which is coupled to the earth through a ground contacting base plate. Means are provided for varying the inclination and azimuth of the vector path traversed by the reciprocating mass, such that any desired combination of compressional and shear waves, both SH and SV type, may be generated and recorded simultaneously at a point on the earth's surface remote from the source.

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: An improvement for the drive control system of a vibratory sound source used in seismic exploration comprising apparatus for generating a feedback signal proportional to the instantaneous acceleration of the reaction mass structure of the sound source's hydraulic drive system. Degenerative feedback of the signal so developed is used to reduce distortion of the vibratory seismic signal imparted into the earth.

Abstract: A hydraulically controlled seismic energy source for impressing individual seismic energy pulses into the ground, wherein the hydraulic pressure forcing the ram downwardly is substantially reduced slightly before the ram contacts the ground, and a continual upward hydraulic force is applied to a downwardly facing surface of the ram, whereby the ram is quickly removed from the ground after a seismic impulse is generated to prevent secondary contact between the ram and the ground.

Abstract: A device for generating pulsed radial stresses to the wall of a well by application of pulses to anchorage shoes of a body lowered in the well, at the end of a cable provided with electric power supply and signal transmission lines. The device comprises hydraulic jacks for controlling the anchorage shoes, a main hydraulic system comprising an accumulator for placing the anchorage shoes in contact with the wall of the well and an auxiliary hydraulic system comprising an accumulator for applying short pulsed radial stresses to the anchorage shoes in the anchorage position. The hydraulic systems are electrically supplied through the cable.

Abstract: A transportable seismic energy source having a baseplate for contacting the earth, an upper master cylinder affixed at its lower end to the base plate and extending uprightly from it, a receiving cylinder of outside diameter less than the internal diameter of the master cylinder and supported coaxially within the upper portion of the master cylinder, the master cylinder and receiving cylinder being filled with liquid, a slug firing gun mounted to the master cylinder and arranged so that the gun muzzle extends coaxially and above the receiving cylinder.

Abstract: A vibratory seismic surface source includes a single vibrating mass, the energy of which is coupled with the earth through a ground contacting base plate. The vibrating mass is connected to the base plate by means of a ball and socket joint which constitutes a universal pivot for the vibratory axis of the mass. Thus, this vibratory axis may be made to assume any vector path with respect to a seismic line. In this manner, any desired combination of compressional and shear waves, both SH and V type, may be generated and recorded simultaneously at a point on the earth's surface remote from the source.

Abstract: A vibratory seismic surface source includes a hydraulic vibrator the energy of which is coupled into the earth through a ground contacting base plate. The vibrator is supported above and independently of the base plate so that it may be pivoted about a first rotational axis within a truck-mounted gimbal-type frame which itself is tiltable about a second horizontal rotational axis perpendicular to the first. After the vibratory axis is oriented in the desired direction the vibrator is lowered so as to contact a suitably contoured upper surface of the base plate. Inclination of the vibrator is accomplished by "push-pull" operation of pairs of oppositely-directed hydraulic cylinders.

Abstract: A device for generating sound pulses in a well by a mobile mass striking against a target element integral with an elongate body anchored in a well by retractable shoes actuated by hydraulic cylinders. The mobile mass which slides in a first chamber in the body is moved away by a piston moving in a second chamber of the body and intermittently locked in the moved away position by a valve. The piston, the valve and also the hydraulic cylinders acting on the anchorage shoes are actuated by a hydraulic system which may be remote controlled from the surface.

Abstract: An apparatus for incremental cylinder length control in a hydraulic vibrator of the type having a reaction mass with a cylinder bore disposed therein, first and second end sleeves disposed in sealed movable position in the ends of the cylinder, a piston rod sealed and slidably disposed through the first and second sleeves with a piston attached to the piston rods where the improvement comprises threading the ends of the cylinder bore and forming mating threads on the first and second sleeves with means for rotating the sleeves with respect to the cylinder so that the sleeves move toward or away from the piston thereby reducing the volume of hydraulic oil between the end of the piston and the end sleeves.

Abstract: A dual mode vibrator assembly for selectively generating either pressure wave or shear wave signals in the earth has a single inertia mass with a plurality of vertically parallel offset cylinder bores and at least one horizontal cylinder bore extending therethrough. Each cylinder bore reciprocably retains a piston member and is in fluid communication with a fluid source. The lower ends of the vertical piston members are connected to a base plate to generate pressure waves. A foot member is connected to each end of the horizontal piston member and interconnected by anti-roll rails in sliding relationship with the inertia mass. Cleats are connected to the bottom of each foot member to engage the earth for generating shear waves. A manifold directs fluid from a servo-valve either to passages leading to the vertical cylinder bores for pressure wave operation or to the horizontal cylinder bore for shear wave operation.

Abstract: A dual-mode vibrator for alternately injecting P-waves and S-waves in the earth including a hydraulically driven shaker assembly, a ground-contacting base plate, and a jacking means for raising and lowering the base plate relative to a vehicle. The shaker assembly is supported above, and coupled to the base plate by a supporting means. The supporting means has a first configuration for coupling the shaker assembly to the base plate for generating P-waves and a second configuration for pivotally coupling the shaker assembly to the base plate and to a rigid member associated with the vehicle for injecting S-waves.

Abstract: An apparatus for preventing thermally-induced stress fatigue in a vibrator support housing consists of a stress compensator that absorbs thermal dimensional changes between major structural components made of dissimilar materials. The stress compensator consists of a hydraulic clamp wedged between the free end of a vibrator actuator piston shaft and the supporting housing. Actuated by the substantially-constant system hydraulic pressure, the hydraulic clamp maintains a substantially constant clamping force between the actuator piston shaft and the supporting housing. Thermally-induced stresses are absorbed by the hydraulic system.

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: 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: A seismic source operable in deep bore holes, and especially suitable for acoustic well logging and geophysical exploration, produces a controlled-spectrum seismic impulse. The source has a hammer which is hydraulically cocked through a hydraulic transformer into a hydraulic spring. Upon command, the hammer can be released, converting stored energy in the spring to kinetic energy of hammer motion. The hammer impacts on a liquid impulse shaping spring which couples impulse energy of controlled spectral width to the formation surrounding the hole by means of a balanced piston assembly which can be prebiased against the side walls of the hole.

Abstract: A seismic vibrator source having an hydraulic vibrator coupled to vibrate a ground pad is provided with one or more force transducers such as, for example, load cells, strain gauges, or piezoelectric elements for measuring the force applied to the earth. Signals indicative of the pressure force are applied to a controller for the hydraulic vibrator to adjust control signals to prevent decoupling of the ground pad from the earth during ground seismic operations.

Abstract: In accordance with an embodiment of this invention, voltages are received from the pilot valve torque motor, the main servo valve and the actuator indicating the value of the torque motor current, spool position and actuator displacement. The received voltages are compared to a preselected threshold value. When one or more of the voltages exceed a threshold value, an attenuator control voltage is generated. An attenuator circuit is coupled between the reference driver signal generator and the DC servo amplifier. The attenuator control voltage, if present, is applied to the attenuator circuit and scales down the reference driver signal as a function of the error signal level thereby to limit the torque motor current and consequently the displacements of the main servo valve spool and actuator shaft.

Abstract: The claimed invention is directed to seismic exploration wherein an earth surface vibrator sweeps through a frequency range with varies with time as a function of frequency.

Abstract: A reaction mass and hydraulic cylinder assembly for a seismic transducer. A hydraulic biasing cylinder (76) is formed between a lower piston rod (32) and a reaction mass (44) and is located below a hydraulic drive cylinder (46). The lower piston rod (32) includes a first portion (36) and a detachable second portion (38-40), the detachable second portion forming an upward facing shoulder (42) which partially defines the hydraulic biasing cylinder (76). The hydraulic drive cylinder (46) is formed by a cylinder sleeve (48) and upper and lower cylinder bushings (50 and 52) having lower and upper ends (54 and 56), respectively, concentrically received within the cylinder sleeve (48) to define the upper and lower ends, respectively, of the hydraulic drive cylinder.

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 dual mode vibrator (DMV), in its hydraulic cylinder, automatically provides a shorter stroke for higher frequencies and a longer stroke for lower frequencies. The cylinder contains a pair of sleeves, each sleeve having one diameter portion sufficient to slideably engage the piston and having a smaller diameter portion to slideably engage the piston rod. The sleeves themselves are moveable within the cylinder, such movement being effected by the application of high pressure on one end or the other. When the sleeves are moved together, the stroke is effectively shortened. When the sleeves are moved apart, the stroke is effectively lengthened.

Abstract: Apparatus for subjecting a test specimen to vibrational forces has a base, a first preselected massmounted for reciprocal movement relative to the base and a second preselected mass elastically coupled to the first mass to produce a resonant condition at a preselected frequency of reciprocal movement.

Abstract: A lightweight rigid housing and baseplate structure for a seismic transducer. The baseplate (12) includes a central hub (26) for receiving a lower piston rod (76). Upper and lower skin plates (32 and 36) extend radially outward from the central hub (26). A plurality of equally angularly spaced reinforcing plates (40) also extend radially outward from the hub (26) and have their upper and lower edges rigidly connected to the upper and lower skin plates. A housing assembly (78) rigidly connects an upper piston rod (74) to the baseplate (12), and includes a frusto-conical section (82). The lightweight rigid housing (78) and baseplate (12) structure provides a seismic transducer having in-phase force distribution over substantially the entire area of the baseplate as it is engaged with the earth.

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: Apparatus for incremental cylinder length control in hydraulic seismic vibrators having increased frequency range. The vibrator apparatus (10) of the type having a reaction mass (38) and axial cylinder bore (42) utilizes hydraulically movable end sleeves (86 and 96) in each end of the cylinder bore (42) so that the end sleeves (86 and 96) can be controllably positioned thereby to alter the cylinder volume and adjust the hydraulic drive system (18) for maximum efficiency relative to operating frequency.

Abstract: A liquid telemetry system is disclosed useful for transmitting data through a fluid body by means of pulses in the fluid. To generate the pulses in the fluid the system utilizes a bi-stable fluid amplifier in conjunction with a vortex valve. Control input signals direct the flow of fluid from the bi-stable amplifier into the vortex valve in such manner as to selectively impede the flow of fluid through the vortex valve. The resulting changes in fluid flow rates generate pulses within the fluid body.

Abstract: A combination of fixed geometry of vibrating masses on a baseplate coupled to the ground, the masses being at a fixed angle to each other and of relatively variable phase, can be controlled to produce both compressional and shear waves simultaneously in a seismic exploration system.

Abstract: A seismic energy generating assembly includes a seismic energy generator positioned within a cage-like frame and adapted for vertical movement within the frame in reaction to the powerful seismic energy impulses that are transmitted downwardly into the earth. The assembly further includes hydraulic catch cylinders for easing the seismic energy generator back down to the ground within the frame after each impulse is generated. Horizontal extensions from this frame ride in guides formed by tubular channels for guiding the entire seismic energy generating assembly when lifted up from the ground by hydraulic lifting cylinders so that the assembly can be readily moved from place to place during seismic exploration. The tubular channels are pivotally mounted to an outer supporting frame on a land vehicle.

Abstract: The present invention relates to means for coupling the horizontally-directed force of a seismic transducer into the earth as a downward going shear wave. The coupling means consists of a plurality of downwardly convergent wedge-shaped earth-engaging cleats mounted on the transducer support means. The cleats differ from each other as to depth and sharpness, the sharper cleats being the deeper ones, so that they contact the earth's surface prior to the blunter ones and penetrate hard surfaces more readily. The blunter cleats, on the other hand, slow the rate of penetration in softer materials and thus prevent bottoming out. The cleats are configured so that the total edge length of the sharper cleats is less than that of the blunter ones, further insuring a high vertical loading on initial contact with hard surfaces. This construction permits efficient coupling into the earth of the horizontal force of a vibrator in soils and other earth materials varying widely in competency while minimizing bottoming out.

Abstract: A telemetry system is disclosed which utilizes a fluid feedback oscillator n conjunction with a flow restricting device in order to generate pulses in a fluid. Means are provided to turn the oscillator on or off or to vary the frequency of oscillation, thereby permitting the transmission of information by means of the fluid pulses.

Abstract: An air gun firing sensor apparatus and system are provided for determining the instant of firing of an air gun by sensing pressure changes within the air gun when it is being fired. A pressure-change-sensitive transducer assembly is inserted into a socket in the housing of a solenoid-controlled valve of an air gun with a passage from the air gun communicating with the transducer for transmitting to the transducer a pressure surge occurring within the air gun whenever it is fired. The transducer assembly has a cylindrical casing with a head mounted at one end. The head includes a plurality of spaced recesses which are adapted to communicate with the passage leading from the air gun.

Abstract: Two or a larger even number of compressional wave producing vibrators are symmetrically disposed in two groups on opposite sides of a profile line in closely spaced relationship. The vibrators are energized by the same (or identical) sweep signals, the signals to one vibrator (or group) on one side of the line being separated in phase by 180.degree. from the signals to the vibrator or group on the other side. P-wave components are thereby cancelled, leaving the shear waves to be propagated.

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: A fluid pulsed generator system including an elongated tubular member of uniform elastic parameters constructed for receiving fluid flow therein and abruptly terminating said flow to create an acoustic pulse containing most of its acoustic energy in the zero to 160 Hertz frequency spectrum. The system generates a directionally distinctive acoustic pulse. The system includes a fluid reservoir adapted for supplying a suitably high fluid pressure for driving a fluid through the elongated tubular member with sufficient velocity to generate an acoustic pulse basically of the classical water hammer variety The device is provided in a marine configuration comprising an elongated acoustic radiating conduit containing the water hammer generated pressure pulse adapted for trailing from a vessel beneath the surface of a body of water.

Abstract: The present invention relates to means for coupling the horizontally directed force of a seismic transducer into the earth with a downward going shear wave. The coupling means consists of a plurality of downwardly convergent wedge-shaped earth engaging cleats of differing depth mounted on the transducer support means. The lateral load-bearing surfaces of the cleats have sloping faces equally inclined to the vertical, so that they tend to compact and compress the earth to a similar degree with horizontal vibrator motion. However, on some or all of the cleats these sloping faces are interrupted by horizontal faces in a stair-case fashion so as to vary the overall sharpness of such cleats.

Abstract: Two fluid passages are connected through flow restrictors to a fluid supply. Downstream of the restrictors the fluid supply has a drooping pressure-load characteristic. Venting means for the fluid passages comprises vent openings therein downstream of the restrictors and variable position obstructor means cooperating with vent openings to vary venting and thereby vary fluid pressures in the fluid passages.Fluid conduits connect these pressure outputs to a double acting piston moving in a cylinder whose opposite ends are connected to the fluid conduits. The piston and cylinder form the responder of the system.A receiver is formed by a piston and cylinder or other fluidic motor remotely fluidically connected to the responder, the motor driving a load.A feedback means controlled by the position of the responder piston and/or the load varies pressure in the fluid conduits by variably venting same.

Abstract: A vibratory seismic energy source capable of generating significant energy over a broad frequency band. The vibrating baseplate and associated structure are designed to have minimum weight while still retaining sufficient structural integrity to permit the use of high actuator forces. This, coupled with a large reaction mass results in the generation of significant energy levels in the earth at high frequencies.

Abstract: A linear actuator 10 for use as a seismic vibrator includes a reaction mass 12 having an internal cylinder 14, and containing a double acting piston 20 to which are attached upper and lower pistons 26 and 28. Hydraulic fluid under pressure is applied alternately to the upper and lower faces of piston 20 to reciprocate it in alternate strokes relative to the reaction mass. Rolling diphragm seals 38 and 40, secured between piston shafts 26, 28 and reaction mass 12, prevent external contamination from reaching laminar seals 30 and 32. Shafts 26 and 28 include enlarged portions 44 and 46 that are contactable with nests of conical springs 52 and 54, mounted at the top and bottom of reaction mass 12, at the displacement limits of piston shafts. Said conical springs absorb energy and limit rebound between the reaction mass and the piston shaft.

Abstract: Apparatus for incremental cylinder length control in hydraulic seismic vibrators having increased frequency range. The vibrator apparatus (10) of the type having a reaction mass (38) and axial cylinder bore (42) utilizes hydraulically movable end sleeves (86 and 96) in each end of the cylinder bore (42) so that the end sleeves (86 and 96) can be controllably positioned thereby to alter the cylinder volume and adjust the hydraulic drive system (18) for maximum efficiency relative to operating frequency.