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 sound source capable of generating high energy acoustic pulses is lowered into a well borehole. A chamber of high pressure air in the source provides the energy for the pulses. A firing mechanism in the source is armed using increased pressure on the drilling mud in the well borehole. The pressurized mud is stored in a chamber in the source having closable ports. When the firing mechanism is operated, the ports are open, forcing the mud from the source into the borehole mud column and causing a cavitation zone in the mud at the ports. When the cavitation zone collapses, an acoustic energy pulse is formed. Pulses may be formed in this manner at the same depth or a number of depths in the well bore during a single run of the source in the well.

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 method and tool for acoustically logging a wellbore where a transmitter simultaneously generates a plurality of separate acoustical signals having different frequencies, each effectively centered about a different resonance frequency, and then transmits the signals as a composite multi-frequency output signal having an effective broad frequency bandwidth that is capable of exciting pressure waves in a variety of different types of earthen formations.

Abstract: An acoustic transmitter for use in a borehole logging tool employs multiple Helmholtz resonators stacked such that apertures in opposite sides of each of the resonators are in linear alignment so as to provide increased acoustic energy output over a broad band of low frequency seismic frequencies.

Abstract: An ultrasonic logging tool (borehole televiewer) which utilizes a rotating transducer which is exposed directly to the fluids in the borehole during logging operations.

Abstract: Apparatus for simultaneously generating elliptically polarized seismic shear waves and compression waves downhole for coupling energy through the fluid into the borehole wall. The apparatus includes an elongate frame for support in the borehole and the frame includes a drive means energizable to impart an orbital motion to at least a portion of the frame thereby to generate an orbital shear wave.

Abstract: A sonic isolation joint (SIJ) of a sonic well logging tool is disposed between a sonic transmitter section and a sonic receiver section of the tool and attenuates compressional and flexural waves which propagate longitudinally along an axis of the tool when the sonic transmitter transmits a pressure wave into a formation of a borehole. The SIJ comprises a first outer housing, a second outer housing, an inner housing disposed within the first and second outer housings, a first attenuation member disposed between the first outer housing and the inner housing and a second attenuation member disposed between the second outer housing and the inner housing, each of the attenuation members including a plurality of rubber isolating washers, and a plurality of steel washers interleaved with the plurality of rubber isolating washers.

Abstract: A method and apparatus are disclosed for carrying out the seismic exploration of the strata which surrounds a borehole during the drilling of that borehole. A compressional mode jar mechanism is disposed in a drill string above a drill bit. Sufficient weights to cock and actuate the jar are disposed both below and above the jar mechanism respectively. A telescoping joint above the jar prevents the impact on the drill bit from propagating up the drill string and multiple geophones at the surface are utilized to receive the seismic waves generated by the impact of the drill bit within the borehole. In a preferred mode of the present invention, an additional geophone is disposed within the drill string proximate to the drill bit to detect the "first break" of the impact thus generated.

Abstract: The invention is the use of standing waves to generate a well log. By measuring changes in energy dissipation from the standing wave along the well-bore, the formation may be evaluated for permeability variations may be determined. Variations in the tube wave velocity may be determined from variations in the frequency of a standing tube wave having a selected wave length. Shear wave velocity of the surrounding formation may be determined from the tube wave velocity.

Abstract: An assembly is provided for generating seismic signals in the earth utilizing one or more shells. A tubular barrel made of frangible material, such as plastic, has a shell positioned within it, the shell having a head with an electrically actuated primer button. A continuity block is positioned within the barrel providing electrical continuity with the shell and the primer button. Conductors are connected to the continuity block and extending exteriorly of the barrel, the shell being fired by connecting the conductors to a voltage source. The barrel may be elongatd to house a plurality of spaced apart shells, the first shell being electrically fired and the other shells being fired by percussion. Each percussion shell is engaged by a plunger which is actuated by the slug fired from the adjacent shell so that upon firing of the electric shell, the slug thereof fires the first percussion shell and each percussion shell thereafter is fired in sequence.

Abstract: A transmitter for a sonic wall logging tool contains a piston, the plane of the piston being disposed along the longitudinal axis of the tool. The piston moves, in its entirety, transversely with respect to the tool when an alternating current flows in two coils disposed in magnetic fields created by two mangets. Sonic positive pressure waves are created on one side of the piston, and sonic negative pressure waves are created on the other side of the piston. Shear waves are created in the formation, a positive shear wave being created in the formation on one side of the tool, and a negative shear wave being created in the formation on the other side of the tool.

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 inflatable attenuator having an inflatable resilient bladder enclosed by a perforated protective cylindrical housing is positioned in a liquid column in a well below (and if desired another inflatable attenuator is also positioned above) an impulsive energy source in the liquid column. The housing has an exterior diameter slightly less than the interior diameter of the well. The bladder is inflated when in the liquid column by gas supplied from a pressurized gas container attached to the attenuator or is supplied with pressurized gas through a hose line from a source of pressurized gas located on the surface of the Earth near the mouth of the well. A pressure-regulator responsive to the ambient hydrostatic pressure in the liquid column near the pressure regulator serves to maintain the pressure of the gas within the bladder at a regulated pressure at least equal to the ambient pressure in the liquid column where it is located.

Abstract: A vibrator and method for transmitting seismic signals into the earth to obtain data on various subsurface characteristics. The vibrator is driven with piezoelectric transducers which can operate below 500 Hz, and can produce better signal resolution at higher frequencies than is possible with hydraulic vibrators. The piezoelectric vibrators can be used in various embodiments at the earth's surface, within a borehole, or while permanently buried in the earth.

Abstract: An improved apparatus for generating a seismic wave in a borehole in the earth is disclosed. A portion of the borehole, which may be the bottom of the hole or any other point along its length, is selected as the site for seismic wave generation. A device is provided to oscillate the borehole fluid in a selected portion of the borehole to establish a resonant standing pressure wave of desired frequency within the fluid. The wave is maintained by continuing to supply energy to the fluid to replace losses due to fluid friction, structural losses and radiated acoustic energy. The standing wave thus created is radiated through the borehole wall into the earth and is eventually received by seismic detectors located on the surface.

Abstract: A transverse-wave logging tool consists of a plurality of sets of transducers mounted around a cylindrical mandrel. The transducer active faces are characterized by two orthogonal dimensions, one of which dimensions is a half-wavelength long relative to the acoustic excitation energy applied to a transmitter transducer and the transverse-wave formation velocity. Receiver transducers detect converted-compressional waves resulting from transverse waves that were generated by the acoustic excitation energy.

Abstract: A suspended structure for coupling a seismic source to the walls of a borehole, in particular for underground prospecting purposes, the structure comprising top (14) and bottom (16) elongate plug elements having transverse dimensions substantially equal to the inside dimensions of the borehole (10), defining therebetween a substantially closed space (32), and suspension elements (30, 50) connecting the bottom plug element to the top plug element without isolating said space from the surrounding walls of the borehole, a seismic source (34) suitable for acting in said space, with the top and bottom plug elements opposing said action in the longitudinal direction of the borehole so that said action is applied essentially against the walls (10) of the borehole level with said space.Applicable to underground prospecting together with pick-up means.

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 controlled implosive downhole seismic source having a substantially hollow closed vessel body adapted to be lowered in a borehole and means for selectively causing at least a portion of the vessel body to implode under pressure thereby producing seismic waves.

Abstract: A down hole periodic seismic generator system for transmitting variable frequency, predominantly shear-wave vibration into earth strata surrounding a borehole. The system comprises a unitary housing operably connected to a well head 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 variable speed pneumatic oscillator and a self-contained pneumatic reservoir for producing a frequency-swept seismic output over a discrete frequency range.

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 system for producing pressure or shear-waves in a solid medium uses a wave generator with at least one primary induction coil and at least one short-circuited secondary coil. The short-circuited secondary coil is rigidly connected to the solid medium for directly transmitting to the solid medium the repulsion force generated between the primary and secondary coils by a short-circuit current caused to flow in the secondary coil when electrical power is applied to the primary coil. Thus, the system is a transformer in which the short-circuited secondary coil is directly used as the tool for the wave application.

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: Multiple downhole seismic signals are generated by an apparatus comprising one or more elongated rod segments insertable in a borehole and provide with spaced-apart predetermined lengths of Primacord explosive charge helically wrapped on the exterior of the rod segment and spaced apart by circumferential baffles supported on the rod segment. The charges are selectively fired through a motor actuated selector switch and a switch stepping and firing circuit including only two conductors and blocking diodes for imposing signals of opposite polarity on the selector switch and its actuating motor.

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 bender acoustic transducer has a flat, piezoelectric element affixed to a flat, elongated inert element. The ends of the inert element are hinged on a supporting rectangular frame which has a rectangular opening. Two sides of the elements are exposed so that when a voltage is applied, a dipole acoustic wave is generated by the transducer.

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 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: 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 acuator has a length of about 1 meter.

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 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: Method of instantaneous acoustic logging within a wellbore.The method is characterized in that it consists of locating on drill-pipe and ground recordings elementary recordings corresponding to one and the same depth level of the drilling tool, in grouping these elementary recordings in pairs, then in intercorrelating said recordings of the pairs so as to produce in respect of each pair a correlated signal which is representative of the acoustic energy produced and of the difference in travel times of the waves received on sensors from which the pair of recordings has been obtained.A particular application is for the determination of a seismic wellbore profile.

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: A spark discharge acoustic pulse transducer for borehole operation provides an insulating ceramic barrier which contains a small cross-section aperture separating two bodies of electrolyte through which the two zones of liquid make contact. An electrical arc discharge is caused to occur through the aperture to produce a transient pressure pulse and associated acoustic pulse which is coupled to the geologic formation at the borehole wall. The specific shape and geometry of the aperture channel in the insulating barrier being exponentially shaped provides a means for controlling the waveform and frequency spectrum of the acoustic pulse. The transducer has an elastic outer housing and an elastic inner housing with hydraulic fluid between the inner and outer housings. The pressure of the hydraulic fluid may be increased to expand the outer housing against a borehold prior to a spark discharge. The transducer is also provided with a system for venting gas produced as a result of the spark discharge.

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: For use in acoustic logging, an acoustic wave transducer system forming both compression and shear waves is disclosed, the system having the preferred form of a plurality of radially directed magnetostrictive expansion means, being N in number, each having a transducer plate affixed to the outer end thereof and further including means for providing a current to a coil wound thereabout forming flux initiating magnetostrictive expansion and contraction to form compression or shear waves.

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: Method and apparatus for acoustic wave generation and transmission into a subsurface earth formation. A logging sonde adapted to be suspended in a borehole within the formation houses a generator means for simultaneously generating a plurality of acoustic waves traveling in the direction of and spaced substantially evenly about the logitudinal axis of the sonde. An acoustic energy reflector means within the housing reflects the waves radially outwards of the axis and into the formation at angles generally perpendicular to the axis. Detectors within the housing spaced longitudinally from the generator and reflector detect acoustic energy in the formation resulting from the reflected waves.

Abstract: Method and apparatus for acoustic wave generation and transmission into a subsurface earth formation, particularly adapted for use in borehole shear wave logging. A logging sonde adapted to be suspended in a borehole traversing a formation houses a source of acoustic waves. The source simultaneously generates a plurality of acoustic waves propagating generally radially outward from locations within the sonde housing adjacent the vertical central axis thereof and will interfere to produce multipole acoustic waves in the formation. Detector means within the housing spaced longitudinally from the source detect acoustic energy in the formation resulting from the generated waves. In a preferred embodiment, the source includes a cross-shaped rod assembly comprised of two rods perpendicular to each other and joined at their mid-points through which the central axis passes.

Abstract: A down-hole signal generator for a mud-pulse telemetry system comprises an annular impeller surrounding a casing and arranged to be driven by the mud passing along the drill string. The impeller serves to drive a torque control arrangement, and preferably also an electrical generator, within the casing. The torque control arrangement is switchable between two states by a signalling actuator in response to an electrical input signal. In a first state the impeller may be driven relatively easily so that it is rotated at a relatively fast speed by the mud flow, whereas, in a second state, a greater torque is required to drive the impeller so that it is rotated at a relatively slow speed. Thus suitable variation of the input signal may be used to vary the impeller speed to transmit a modulated pressure signal in the mud flow which may be sensed at the surface.

Abstract: A method and apparatus for generating a seismic wave in a borehole in the earth is disclosed. A portion of the borehole, which may be the bottom of the hole or any other point along its length, is selected as the site for seismic wave generation. A device is provided to oscillate the borehole fluid in a selected portion of the borehole to establish a resonant standing pressure wave of desired frequency within the fluid. The wave is maintained by continuing to supply energy to the fluid to replace losses due to fluid friction, structural losses and radiated acoustic energy. The standing wave thus created is radiated through the borehole wall into the earth and is eventually received by seismic detectors located on the surface.

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 electrodeless spark discharge acoustic pulse transducer for borehold operations provides an insulating ceramic barrier which contains a small cross-section aperture separating two bodies of electrolyte through which the two zones of liquid make contact. The specific shape and geometry of the insulating barrier being exponentially shaped provides a means for controlling the waveform and frequency spectrum of the acoustic pulse. The transducer has an elastic outer housing and an elastic inner housing with hydraulic fluid between the inner and outer housings. The pressure of the hydraulic fluid may be increased to expand the outer housing against a borehole prior to a spark discharge. The transducer is also provided with a system for venting gas produced as a result of the spark discharge.

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: Acoustic well logging method and system employing a bender-type transducer as a point source of an acoustic shear wave. The bender-type transducer includes opposed unrestricted planar surfaces mounted within a liquid filled compartment within the tool. The unrestricted surfaces of the transducer are spaced longitudinally along the axis of the tool and exposed to the coupling liquid. One or more bender-type transducers may also be employed as acoustic receivers in the tools. The active surfaces of the receiving transducers are oriented in substantially the same direction as the active surfaces of the transmitting transducer.

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: 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: Apparatus for generation of shear or compressional type vibrations within a borehole wherein oppositely oriented first and second acoustic energy sources are energized to produce output tube waves which, in turn, are equally deflected to propagate energy toward opposite sides of the borehole. Energization of the sources in-phase effects output of compressional wave energy and energization of sources 180.degree. out of phase results in shear wave generation.

Abstract: Apparatus for continuous shear wave logging of a borehole consisting of a sonde instrument having retractable, expandable coupling arms for rigidly engaging the borehole wall to exert repetitive torqueing action while continuously moving uphole. The sonde includes spaced detector coupling arms in continual contact with the borehole wall and polarized for detection of the repetitive propagated shear waves.