Abstract: A downhole electro-hydraulic vertical shear wave seismic source places the reaction mass internal to the source cylindrical housing and isolates the actuator from the wellbore fluid and pressure. The clamping system of this source uses two serrated pads radiused to match the inside diameter of the casing. Hydraulic cylinders which are retracted by internal compact stacks of spring washers are used for actuating the serrated pads. A device for keeping the reaction mass in a "floating" position with actuator piston centered within the actuator cylinder is provided by suspending the reaction mass from a compact and soft urethane spring. A threaded guide rod passing vertically through this spring allows spring compression to be adjusted until the actuator piston is precisely centered with no differential hydraulic pressure across the piston.

Abstract: An apparatus for generating vibrational energy in a borehole including an elongated mass having a surface of diameter less than the borehole, a rotary source for suspending the cylindrical mass in a borehole and a system to cause frictional contact between the surface of the mass and the borehole wall, the cylindrical mass being rotatable about its rotational axis in one direction to cause the mass to backward whirl in the opposite direction within the borehole, the cylindrical force of the whirling mass serving to generate vibrational energy in the borehole.

Abstract: The SH wave generating apparatus includes a driving plate (1) of increased rigidity; a fixing device (6) provided on the bottom of the driving plate for fixing the driving plate onto the earth's surface; a plurality of hydraulic actuators (2) mounted on the driving plate, which have reaction masses and act tangentially on the same circumference from the center of the driving plate; and a driving device (4,5) for reciprocating the plurality of hydraulic actuators (2) at a controlled frequency, thereby generating transverse waves. The plurality of hydraulic actuators (2) are equidistantly mounted on the driving plate (1), and each include a cylinder (2) and a piston rod extending therethrough. The said piston rod is mounted at both ends on supports (3) fixed to the driving plate (1) and the cylinder acts as a reaction mass. Alternatively, the piston rod extending through the cylinder 2 may be provided at both ends with reaction masses.

Abstract: A downhole seismic energy source for use in generating a seismic signal in a borehole including an elongated mass having a generally cylindrical surface of diameter less than the borehole, an actuator suspending the cylindrical mass in the borehole wherein the cylindrical surface thereof is in frictional contact with the borehole wall, the cylindrical mass being rotatable about its rotational axis to cause the mass to whirl within the borehole in the direction opposite the direction of the rotation of the mass, the mass cylindrical force serving to create a seismic energy signal.

Abstract: A method and an apparatus for mass retrieval for an acoustic pulse generator are disclosed herein. In an impulse type seismic generating apparatus an air spring, mechanical spring, controlled pressurization of an air spring or other energy storage medium is employed to use potential energy to raise the impact mass to a resting position above an earth contacting baseplate as quickly as possible after the impact mass strikes the baseplate.

Abstract: A seismic source for emitting vibrations through rotation of a set of eccentric weights. Two pairs of angularly out-of-phase weights (A1, A2 and C1, C2) rotate in the same direction. One pair of weight (B1, B2) of twice the mass of each of the first pairs of weights (A1, A2 or C1, C2), also angularly out of phase in relation to one another, rotates in the direction opposite to that of the first pairs of weights and at the same speed. All the weights are rotated by electric motors. An electronic set (ME1, ME2) receives control signals (cp1-cp6 and ac1-ac3) representative at any moment of the position of all the weights and out of direction of the generated resulting vibration, and produces electric currents (IMA1-IMA6) driving the motors, as well as currents (ICH, EV) necessary for controlling a hydraulic plant to secure the source against an application wall. The electronic set automatically controls the vibration in order to obtain the desired oscillation direction, frequency and intensity.

Abstract: Apparatus is described for placement in a borehole in the earth, which enables the generation of closely controlled seismic waves from the borehole. Pure torsional shear waves are generated by an apparatus which includes a stator element fixed to the borehole walls and a rotor element which is electrically driven to rapidly oscillate on the stator element to cause reaction forces transmitted through the borehole walls to the surrounding earth. Logitudinal shear waves are generated by an armature that is driven to rapidly oscillate along the axis of the borehole relative to a stator that is clamped to the borehole, to cause reaction forces transmitted to the surrounding earth. Pressure waves are generated by electrically driving pistons that press against opposite ends of a hydraulic reservoir that fills the borehole. High power is generated by energizing the elements at a power level that causes heating to over 150.degree. C.

Abstract: The method and apparatus for providing elliptical polarized shear waves in a marine environment in which a shear wave source penetrates the surface sediment of a water bottom includes dual actuator/reaction mass system mounted inside a structural ring of a conical housing section. A cross shaped structure at the top of the apparatus serves as a passive reaction mass and as a moment arm support for reversibly motor driven propellers enclosed in shrouds at the outer ends of the cross shaped structure. A thruster system provides dynamic positioning. The cross shaped structure and housing section are connected by a structurally stiff member, such as a vertical tube. Pistons provide actuation of two reaction masses located within the housing structure, and the motions of the reaction masses generate shear waves which propagate in the subsurface formations.

Abstract: An anti-bounce device for a mass striking a target element, with the device including a counter-mass and an arrangement for holding the counter-mass spaced from the mass at a predetermined distance and for braking the mass and the counter-mass to delay the counter-mass so as to put the counter-mass in a phase opposition with the mass as the mass bounces after impact thereby dissipating any bouncing forces. The linking and braking arrangement may include a volume of fluid in a chamber provided between the mass and the counter-mass or a layer of damping material interposed between the mass and counter-mass.

Abstract: A downhole hydraulic seismic generator system for transmitting energy wave vibrations into earth strata surrounding a borehole. The system contains an elongated, unitary housing operably connected to a well head aboveground by support and electrical cabling, and contains clamping apparatus for selectively clamping the housing to the walls of the borehole. The system further comprises a hydraulic oscillator containing a double-actuating piston whose movement is controlled by an electro-servovalve regulating a high pressure hydraulic fluid flow into and out of upper and lower chambers surrounding the piston. The spent hydraulic fluid from the hydraulic oscillator is stored and pumped back into the system to provide high pressure fluid for conducting another run at the same, or a different location within the borehole.

Abstract: An apparatus for generating SH waves comprises a casing, a rotor, stator, a flywheel connected to the rotor and a controller for controlling the rotation of the flywheel. The flywheel is first rotated at a predetermined speed, and then its rotation speed is decreased or increased continuously or intermittently, thereby to generate the SH wave onto an objective solid body.

Abstract: An anti-bounce device for a mass striking a target element, with the device including a counter mass and a linking arrangement for holding the counter mass spaced from the mass and a braking arrangement for delaying the counter mass so as to put the counter mass in phase opposition with the mass as the mass bounces after impact thereby dissipating any bouncing force. The linking arrangement may take the form of a volume of fluid in a chamber provided between the mass and counter mass, and the linking arrangement and braking arrangement may also include a layer of a damping material or deformable or flexible elements acting by friction.

Abstract: Seismic signal generating apparatus of the impact type that includes a signal generator having an impact mass therein, a base plate or coupling member that is engaged by the impact mass to generate the signal, a housing attached to the generator that encircles the impact mass and extends toward the base plate, and means for excluding water from within the housing so that the impact mass travels only through gas prior to engaging the anvil. The apparatus also includes control means for positioning the generator angularly and azimuthally.

Abstract: A downhole seismic generator that can be located in various positions in the well including being located in engagement with the bottom of the well bore and that includes a large striker mass driven by compressed gas into engagement with an anvil having one end located in engagement with the medium in which the seismic signals are to be set up. Retractor means is provided to return the mass to the ready position so that a series of seismic signals can be provided as desired. Optional baffle means connected to the generator prevent waves from traveling through the well bore which would otherwise diminish or confuse the seismic shock wave initially generated.

Abstract: A compressible fluid powered oscillating downhole seismic source device capable of periodically generating uncontaminated horizontally-propagated, shear waves is provided. A compressible fluid generated oscillation is created within the device which imparts an oscillation to a housing when the device is installed in a housing such as the cylinder off an existing downhole tool, thereby a torsional seismic source is established. Horizontal waves are transferred to the surrounding bore hole medium through downhole clamping.

Abstract: An apparatus and method for maximizing the shear wave energy imparted into the soil upon the impacting of a base plate by an impact mass from a seismic generator. A seismic generator is disposed at an angle relative to a line generally perpendicular to the surface to the ground. The angle varies with soil conditions and the angle is determined by locating an accelerometer on the base plate of the generator and observing the horizontal acceleration rate as indicated by the accelerometer. If the acceleration rate exceeds a predetermined value, the anguular disposition of the generator s changed to decrease the angle either manually or automatically until the acceleration rate no longer exceeds a predetermined value.

Abstract: Alignment restoring apparatus for use with seismic shock generators that includes a support frame, a lift frame supported by the support frame, a seismic generator peripherally supported by the lift frame, and a base plate supported by the life frame and arranged to be impacted by the seismic generator. The alignment restoring apparatus includes biasing means located between the lift frame and the base plate to provide a restoring force upon movement of the frame relative to the base plate whereby the initial relationship between the frame and base plate is re-established assuring that the time lapse from initiating the propulsion of the seismic generator toward the base plate to the time of impact therebetween is repeatable.

Abstract: Apparatus for generating a controlled parameter elliptically polarized shear wave into an earth medium. The apparatus consists of a baseplate for engagement with the earth medium in omni-directionally resistant manner and a reaction mass and actuator assembly affixed thereto and energizable to impart reciprocal lateral forces to the baseplate that exert a predetermined resultant force at a controlled rate of rotation.

Abstract: An anti-bounce device for avoiding the multiple shocks of a moving mass after a first impact against another element. Magnetic arrangements are associated with element for exerting an attractive force on the mass sufficient to prevent possible bouncing. These arrangements comprise, for example electromagnets and circuits for connecting the electromagnets to a current source via a switch. Permanent magnets may also be associated therewith. The direction of the electric current is then chosen so that the electromagnetic forces developed are added to the attractive forces of the permanent magnets or else for cancelling these latter out, which allows the mass to be released.

Abstract: A device for generating acoustic waves in a well by causing a mass falling inside a body to strike a target element and to transmit impacts to the surrounding geological formations by anchoring the body in the well by retractable shoes. A tractive force exerted on the support cable from the surface, after anchorage of the body, causes a support element to move upwards which takes the target element and the mass with it. When the mass is hydraulically locked in its set position, the cable is slackened so that the target element and the support element can come back to the bottom position. In this position, the support element presses on a pusher element which actuates hydraulic locking and releases the mass.

Abstract: A wheeled, self-propelled tractor has a percussion tool or hammer mounted on its forward end and an impact transmitting means carried on the tractor below the hammer. In accordance with one aspect of the invention, the impact transmitting means comprises a metal frame having a strong rigid top plate that is struck by the hammer and a downwardly opening cavity in which wood timbers are mounted to transmit the impact from the plate to a cemetery marker. Repeated blows to the market applied through the impact transmitting means will drive the marker into the ground until it is flush with the ground surface where it will not interfere with mowing. The frame is fastened on the vehicle by a suspension system that includes tension springs which keep the wood timbers in a horizontal plane but permit the frame to move downwardly each time it is struck by the hammer.

Abstract: In a method of seismic exploration using swept-frequency signals, compressional and shear waves are emitted simultaneously. Typically the waves are generated by swinging-weight vibrators acting through a single baseplate. If the frequency of the shear vibration is one-half that of the comopressional vibration, the downward vertical forces can be phased to minimize the horizontal slippage of the baseplate. The sensitive axis of the geophones is inclined to the vertical for detecting both compressional waves and shear waves. For defined ranges of sweep rate, separate compressional and shear records are obtained by cross-correlating the geophone signal separately against the vertical and horizontal emissions.

Abstract: A device for generating elliptically polarized shear waves for introduction into a soft earth medium including marshy and water-covered earth surfaces. The device consists of a shear wave generator coupled to a coupling tube having a conical lower end that is maintained in energy-coupling relationship within the earth medium. Shear waves such as elliptically generated shear waves are introduced into the tube member for travel along the tube and further earth coupling about the bottom cone member as it is progressively driven into the earth medium. Suitable hold-down weight is utilized to maintain most effective coupling pressure on the cone member, and, support equipment, either land or marine vehicle, may include crane and alignment structure for continually maintaining the tubular vibrator member in proper vertical attitude during operation.

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: Apparatus for generating a controlled parameter elliptically polarized shear wave into an earth medium. The apparatus consists of a baseplate for engagement with the earth medium in omni-directionally resistant manner and a reaction mass and actuator assembly affixed thereto and energizable to impart reciprocal lateral forces to the base-plate that exert a predetermined resultant force at a controlled rate of rotation.

Abstract: A device for generating in the ground longitudinal and transverse acoustic waves by a mass striking a target element coupled with the surface of the ground. The target element is recessed in a central part thereof and have an inner wall slanted with respect to the vertical in the form of, for example, a truncated cone. The mass is fixed to the end of an arm pivoting with respect to a support structure in the form of a parallelepipedic cage, which is movable by a cylinder between a high transport position and a low position in which the target element is coupled with the ground a drive causes raising of the mass by pivoting the arm with the geometry of the assembly being calculated so that the mass strikes the inner slanting faces perpendicularly thereto, and thus creates both P and S waves.

Abstract: The improved seismic vibration apparatus includes variable length control means located so as to effectively and efficiently position the vibrator relative to the base plate and apparatus to isolate the vibrator from the control system and from the vehicle frame so that effective seismic vibration is imparted into the base plate and consequently into the earth.

Abstract: An electromagnetic vibrator for seismic and civil-engineering applications is provided with a supporting structure fitted with a coupling element, and a reaction mass, which is to be caused to vibrate, with an electromagnetic drive associated therewith and provided at least with electromagnetic coils. The reaction mass is magnetically suspended on the supporting structure by means of one or more magnets with the associated electromagnetic coils and is at the same time caused to vibrate by the electromagnetic drive. The vibration force is exerted on the pole surface of the one or more magnets and the reaction mass is accelerated to at most the acceleration due to gravity.

Abstract: An impact type surface seismic source powered by compressed air includes an elongated piston which moves within the bore of a cylindrical firing tube suitably mounted above an earth contacting target. The firing tube consists of two or more tubular sections slidably joined in telescopic relation. When the piston is allowed to fall from a cocked position, compressed air enters the bore above the piston through side ports and drives the piston downwardly. At the same time, the inner sliding section or sections of the firing tube are exposed to the same air pressure within the bore and are also driven downwardly. In this way, the bore of the firing tube lengthens automatically to provide a longer stroke for the piston and thus a greater attained kinetic energy of impact for a given operating pressure as the piston reaches the target. The apparatus is designed for mounting on a transport vehicle so that the firing tube itself may be raised in operation and lowered for reduced vehicle profile during transport.

Abstract: The invention relates to a nondestructive downhole seismic source capable of generating S.sub.V -waves, S.sub.H -waves, and P-waves alone or in combination to determine information about a surrounding geologic formation. The invention also includes processes of performing crosswell tomography and reverse vertical seismic profiling. The invention also includes a means and process to carry out in hole seismic logging operations.

Abstract: A baseplate assembly for an impulsive, vehicle-transported seismic wave generator for use on rocky, irregular earth surfaces is comprised of a small diameter, earth-contacting, freely movable target member which is laterally confined in the center of a surrounding wide area frame adapted to support vehicle weight directly against the earth. Such a target member may safely be subjected to high dynamic loading per unit area responsive to the impact of a descending mass.

Abstract: An impulsive seismic generator is mounted on a swamp buggy suitable for operations both in a marshy environment and on land. The generator employs a target plate which may be lowered into a body of water or mud beneath the buggy so as to contact subsurfaces of varying degrees of firmness. The submerged components of the generator are surrounded by a water-tight barrier which isolates the space between a descending mass and the receiving target plate from the surrounding fluid.

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: 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 hydraulic vibrator having an adjustable piston rod and a fixed piston rod to vary the cylinder volume for operation at different vibration frequencies. The adjustable piston rod is in threaded engagement with the fixed piston rod and has a piston head adjacent a piston head on the fixed piston rod. Rotation of the adjustable piston rod displaces the two piston heads, thereby varying the cylinder volume of the hydraulic vibrator.

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: The invention relates to a nondestructive downhole seismic source capable of generating S.sub.V -waves, S.sub.H -waves, and P-waves alone or in combination to determine information about a surrounding geologic formation. The invention also includes processes of performing crosswell tomography and reverse vertical seismic profiling. The invention also includes a means and process to carry out in hole seismic logging operations.

Abstract: Device for generating seismic impulses for, for example, seismic prospecting, inside a hole or drilling well by impact of a weight or mass falling onto a target element coupled with a wall of the hole or drilling well. The target element is bound up with a variable volume anchorage element capable of being expanded so that it strikes against the wall of the hole or drilling well and is surmounted by a guiding column along which slides a hammer or weight forming the mass. A cable lifting system and magnetic devices enable the hammer or weight to be hoisted to a particular height above the target element.

Abstract: A stilt structure for a vibrator assembly in which the spider members on each end of the actuator are pivotally coupled to the vertical supports (stilts). The pivotal connection allows rotation of each component thereby eliminating induced bending moments between the spider members and the vertical supports.

Abstract: A device is provided for generating acoustic waves by means of a falling mass striking a target element integral with rectractable anchorage means. The mass moves in an elongate body under the combined action of gravity and resilient means from a raised position to an impact position. Resetting, after the fall, is provided by raising the mass by means of a nut, held against rotation, using a threaded rod connected to reversible drive means and locking it in the high position either by means of a retractable bar tripped by the return of the nut to the low position or else by remote controlled magnetic means. The anchorage means include for example a "packer" and a resilient coupling means.

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: A swinging-weight seismic vibrator is driven by the energy stored in a flywheel. Since the sweep rate is large near the resonance of the vibrator-ground coupling, and small away from resonance, a measure of compensation of the resonance is automatically obtained. Weights of variable eccentricity may be provided. Multiple vibrators may be used, provided that no two vibrators generate the same frequency at times separated by less than the maximum reflection time of interest.

Abstract: This invention is an improved type of shear wave vibrator are carried by a support vehicle and utilizing telescoping tubes for energy engagement within an underlying earth medium. A shear wave vibrator so constructed is particularly desirable for use over marshy or soft surface earth areas. The device consists of a jack assembly supporting a shear wave vibrator relative to a suitable carrier vehicle in vibrationally isolated manner. The vibrator structure consists of a pair of parallel, elongatable telescoping blades for earth penetration and engagement with a passive reaction mass pivotally secured across the top portion of the telescoping blades and an active mass/vibrator system pivotally secured across the lower portion of the telescoping blades adjacent the earth surface.

Abstract: The weight of a transport vehicle and the actuator of an impact type seismic source carried thereby is partially transferred by means of hydraulic lift cylinders to a freely movable earth contacting baseplate positioned beneath the actuator. In operation a mass is propelled by the actuator along a prescribed slant path to strike the baseplate. Shear strain is induced in elastomeric pads sandwiched between the hydraulic lift cylinders and the baseplate if the baseplate shifts sideways under such a slanting blow. The pads then exert a force to restore the vehicle and the actuator to a correct perpendicular alignment over the baseplate. Upper and lower position locator means fixed respectively to the hydraulic lift cylinders and to the baseplate interface with the elastomeric pads and fit slidably within each other so as to transmit vertical force from vehicle to baseplate.

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 preloaded vibrator assembly wherein each leg of a stilt structure is preloaded in compression during construction. The linear actuator is preloaded prior to operation by supplying hydraulic fluid under pressure between one end of the linear actuator piston and the hub of the stilt-structure spider. A structural deflection of the spider away from the piston rod is created by the hydraulic pressure. At a predetermined load, a mechanical lock is engaged, fixing the relative positions of the spider and the piston rod. Hydraulic pressure is removed leaving the structure preloaded.

Abstract: A wheeled, self-propelled tractor has a percussion tool or hammer mounted on its forward end and an impact transmitting means carried on the tractor below the hammer. In accordance with one aspect of the invention, the impact transmitting means comprises a metal frame having a strong rigid top plate that is struck by the hammer and a downwardly opening cavity in which wood timbers are mounted to transmit the impact from the plate to a cemetery marker. Repeated blows to the marker applied through the impact transmitting means will drive the marker into the ground until it is flush with the ground surface where it will not interfere with mowing. The frame is fastened on the vehicle by a suspension system that includes tension springs which keep the wood timbers in a horizontal plane but permit the frame to move downwardly each time it is struck by the hammer.

Abstract: The present invention is a downhole seismic source capable of generating seismic forces in excess of 1000 newtons. The source produces seismic waves for seismic applications, particularly cross borehole measurements and vertical seismic profiling. Coupled with motion sensing devices, the present invention also performs as a seismic logging tool. The source is comprised of an outer housing, a means for clamping the source securely to the wellbore, and a linear electromagnetic actuator which utilizes permanent magnetic material having remanent magnetic field exceeding about 0.9 T such as rare earth permanent magnetics. The source has a diameter of about 12.5 cm to fit within a typical wellbore and the actuator has a length of about 1 meter.

Abstract: An orbital vibratory mass is used for generating seismic signals and the like. An annular reaction mass is mounted on a crank by means of bearing. The reaction mass orbitally oscillates relative to the axis of the crank shaft without rotating. This reduces the internal forces created in the reaction mass by centrifugal force and enables less exotic, less expensive materials to be used in its construction.