Abstract: A seismic vibrator is configured to operate close to resonance for range of actuating frequencies. The vibrator has a baseplate, a reaction mass coupled to the baseplate via an elastic coupling mechanism and an actuator configured to displace the reaction mass with an actuating frequency. The vibrator also has a frequency-adjusting system configured to adjust a natural frequency of the elastic coupling mechanism and the reaction mass, to track the actuating frequency so that to achieve resonance.

Abstract: Earth vibrators, such as servo-hydraulic vibrators, are improved to produce more output force and less distortion at very low frequencies by capturing mass from the vehicles which carry them, adding sufficient inertial mass to the reaction mass without adding much vehicle and equipment weight while also avoiding increases to the servo-hydraulic vibrator's stroke length. In particular, improvements to servo-hydraulic vibrators, at low frequencies, will couple some mass from the carrier vehicle frame and its load using non-rigid coupling only when additional mass is needed using dampers connected between the reaction mass and the carrier vehicle's frame, with the added damping being applied by a control system at very low frequencies of output where the vibrator is otherwise unable to produce force equal to its hold-weight.

Abstract: The invention relates to a hydrophone housing. The housing comprises an outer casing with an exterior shape being in close contact with sediment when buried therein and having a deflectable wall part. Solid material partly fills the casing to define an outer chamber behind the deflectable wall part, a cavity shaped so that an inner chamber is defined immediately surrounding a hydrophone sensing element held therein, and a first duct for liquid flow communication between the outer chamber and the cavity or an internal volume of the hydrophone sensing element. Thereby, a hydraulic coupling is provided so that an acoustic pressure causing small radial displacements of outer surface of the housing will, via liquid in the first duct, cause large radial displacements of the hydrophone sensitive element.

Abstract: A dipole source for borehole acoustic logging includes a cylindrical shell, a center beam coupled to the cylindrical shell, a movable projector inside the cylindrical shell to impact the center beam, and a cavity acoustically insulating the interior of the cylindrical shell from the exterior of the cylindrical shell. An acoustic logging tool for making measurements of a substrate surrounding a borehole with a body insertable in the borehole is also provided. The body includes an acoustic detector and a dipole source as above, along the axial length. The acoustic logging tool may include a control unit to process data collected from the acoustic detector and obtain information about the substrate surrounding the borehole.

Abstract: An apparatus is provided for compacting the ballast bed of a track, comprising a machine frame which is movable on the track with a stabiliser unit which runs on rollers on the track and is equipped with a vibration drive for producing a vibration in a plane parallel to the track. The stabiliser unit is preferably equipped with tension rollers engaging around the rail head. The stabiliser unit is linked in a height-adjustable manner to the machine frame with an adjusting drive and can be moved against the track under load. In order to provide advantageous constructional conditions it is provided that the vibration drive comprises at least one cylinder vibrator which is formed by a hydraulic cylinder and is triggered via a proportional or servo valve.

Abstract: A method to induce pressure transients in fluids for use in hydrocarbon recovery operations by inducing the pressure transients in a fluid by a collision process. The collision process employs a moving object (103,203,303,403) that collides outside the fluid with a body (102,202,302,402) that is in contact with the fluid inside a partly enclosed space (101,201,301,401). Furthermore, the pressure transients must be allowed to propagate in the fluid. The fluid may be one or more of the following group: primarily water, consolidation fluid, treatment fluid, cleaning fluid, drilling fluid, fracturing fluid and cement.

Abstract: According to an embodiment of the instant invention there is provided a method for collecting a blended source seismic survey that utilizes new approach to determining a random time separation between successive shots. The random time separation may be drawn in some embodiments from a distribution of uniformly distributed numbers, with ?>1/(2 f), where ? is the half-width of the uniform distribution and f is the lowest frequency of interest in the survey.

Abstract: An air gun for use in generating seismic energy impulses operable at pressures below 1000 psi that reduces high frequencies and cavitation around the discharge of the air gun in order to mitigate damage to the marine environment, the air gun providing a sliding seal at the firing piston, an extension of port widths beyond the diameter of the firing piston and capability to control the speed of the shuttle assembly to reduce and eliminate some of the possible causes of the objectionable high frequencies and cavitation.

Abstract: Various implementations described herein are directed to a method of performing a seismic survey operation. The method may include receiving a target acoustic output for a seismic survey. The method may include selecting an operating chamber liner for an airgun to be used in a seismic survey that corresponds to the target acoustic output. The method may also include performing a seismic survey using the airgun having the selected operating chamber liner.

Abstract: A seismic source array includes a first source and a second source. The first source has a first spectral output and the second source has a second spectral output different than the first spectral output. The first source has a first total volume different than a second total volume of the second source.

Abstract: A source element for generating seismic waves includes a housing; a partitioning element placed inside the housing and configured to split the housing in a closed chamber and an opened chamber; and a valve in fluid communication with the closed chamber and configured to supply high-pressure air to the closed chamber to make the partitioning element oscillates. An oscillation of the partitioning element generates low-frequency seismic waves.

Abstract: Techniques are disclosed herein relating to distribution of fluids. These techniques may be useful in, for example, supplying pressurized air to seismic sources (or arrays of seismic sources), such as those used in marine seismic operations. Some embodiments of this disclosure include a pipe that passes through a fluid distribution block. The pipe may be configured such that it is able to slide along and/or twist about a longitudinal axis of the distribution block. This technique may reduce the effects of the various stresses that may operate on marine seismic source equipment as it is towed through a body of water.

Abstract: An air gun for use in generating seismic energy impulses operable at pressures below 1000 psi that reduces high frequencies and cavitation around the discharge of the air gun in order to mitigate damage to the marine environment, the air gun providing a sliding seal at the firing piston, an extension of port widths beyond the diameter of the firing piston and capability to control the speed of the shuttle assembly to reduce and eliminate some of the possible causes of the objectionable high frequencies and cavitation.

Abstract: A seismic source array includes a first source and a second source. The first source has a first spectral output and the second source has a second spectral output different than the first spectral output. The first source has a first total volume different than a second total volume of the second source.

Abstract: A seismic source signal apparatus for generating a seismic source signal may include a seismic source component for coupling a reaction mass to the earth; a controllable valve operatively connected to the seismic source component; and a controller controlling the controllable valve with a primary control signal generated by using a model of a response of the controllable valve over a selected operating range. The model is used to reduce nonlinearity in flow versus displacement response of the controllable valve.

Abstract: A seismic energy source includes an inlet aperture and an inlet pipe in fluid communication with an outlet of the inlet aperture at an inlet end of the inlet pipe. The inlet pipe is in fluid communication with an accumulator at an outlet end of the inlet pipe. An outlet pipe is in fluid communication with the accumulator at an inlet end of the outlet pipe and is connected to an outlet valve at an outlet end of the outlet pipe. The outlet valve is actuated by fluid pressure in the outlet pipe. An actuation pressure of the valve, and diameter, length and material properties of the outlet pipe are selected to cause a reflected water pressure wave resulting from closure of the valve to travel within the outlet pipe at a selected velocity. Motion of the seismic source through the water provides water pressure to operate the source.

Abstract: A method for attenuating out of band energy emitted from a seismic source used in a marine seismic survey. The method includes disposing the seismic source in a body of water and releasing a gas into a volume of water surrounding the seismic source. The released gas may be configured such that it displaces the volume of water surrounding the seismic source at a rate less than 2.9×106 cubic-meters per cubic-second.

Abstract: A method for attenuating out of band energy emitted from a seismic source used in a marine seismic survey. The method includes disposing the seismic source in a body of water and releasing a gas into a volume of water surrounding the seismic source. The released gas may be configured such that it displaces the volume of water surrounding the seismic source at a rate less than 2.9×106 cubic-meters per cubic-second.

Abstract: A seismic vibrator has a base plate with at least four isolators isolating a frame from the base plate. Each of these isolators is offset from the plate's footprint on shelves to free up area on the plate's top surface. An accelerometer disposed directly on the base plate detects the acceleration imparted to the plate. To reduce flexing and bending, the plate has an increased stiffness and approximately the same mass of a plate for a comparably rated vibrator. The accelerometer disposes at a particular location of the plate that experiences transition between longitudinal flexing along the plate's length. This transition location better represents the actual acceleration of the plate during vibration and avoids overly increased and decreased acceleration readings that would be obtained from other locations on the plate.

Abstract: A hybrid water cannon that can be configured in either a recoil mode or recoilless mode. A first barrel is attached to a breech block. Either a second barrel or breech plug is also attached to the breech block on a side opposite the first barrel. With the breech plug attached, the water cannon is in a recoil mode. With the second barrel attached, the water cannon is in a recoilless mode. A chamber containing a propellant charge is in communication with both the first and second barrels. Upon ignition, the propellant charge pushes a charge of water from both barrels simultaneously and in opposite directions. The discharge from the first barrel is used to disable the target ordnance. The discharge from the second barrel counters the recoil. The propellant charge is ignited using an ignition charge in a port intersecting the chamber at an angle other than 90 degrees.

Abstract: A seismic source signal generator includes a mass, a primary accumulator and a secondary accumulator, the secondary accumulator having an internal volume smaller than an internal volume of the primary accumulator. A method for generating a signal using a seismic vibrator includes operating the seismic vibrator using hydraulic fluid, damping hydraulic pressure deviations in the hydraulic fluid using a first accumulator in hydraulic communication with the hydraulic fluid, and damping pressure deviations in the hydraulic fluid using a second accumulator in hydraulic communication with the hydraulic fluid, the second accumulator having an internal volume smaller than an internal volume of the first accumulator.

Abstract: An apparatus for generating seismic body waves in a hydrocarbon reservoir includes a closed-loop borehole source having a resonant cavity for generating resonant energy, a drive source and a control unit. The drive source injects pressure pulses to the resonant cavity at a predetermined or selectable pressure and frequency. The fluid circulates between the cavity and the drive source in a closed-loop fashion. In another embodiment, the borehole source utilizes a smart or controllable material that is responsive to an applied excitation field. The cavity includes an excitation coil for providing an excitation field that changes a material property of the smart fluid. The control unit is programmed to adjust operating parameters to produce seismic waves having a selected frequency and amplitude. In one embodiment, a control unit adjusts operating parameters in response to measured parameters of interest or surface commands.

Abstract: A seismic source signal generator includes a mass, a primary accumulator and a secondary accumulator, the secondary accumulator having an internal volume smaller than an internal volume of the primary accumulator. A method for generating a signal using a seismic vibrator includes operating the seismic vibrator using hydraulic fluid, damping hydraulic pressure deviations in the hydraulic fluid using a first accumulator in hydraulic communication with the hydraulic fluid, and damping pressure deviations in the hydraulic fluid using a second accumulator in hydraulic communication with the hydraulic fluid, the second accumulator having an internal volume smaller than an internal volume of the first accumulator.

Abstract: A shear wave generator for use subsea, including an excitation unit that is fastened to a top plate; a skirt, the upper end of which is fastened sealingly to the top plate and extending downward to an open lower end of the skirt, such that the top plate and skirt form a closed space by lowering to the seabed; and a pump arranged with fluid communication between the space and the surroundings, such that by pumping water out of the space, an underpressure is formed acting to suck the shear wave generator fixedly to and partly into the seabed, and by pumping water into the space, an overpressure is formed acting to lift the shear wave generator up from the seabed. The shear wave generator is distinguished in that the skirt is formed with a larger outer diameter or width at its upper end than at its lower end.

Abstract: A marine seismic source method capable of retaining low frequencies is disclosed. One embodiment of the method comprises a seismic source that generates an up-going wave and first down-going wave with opposite polarity. The up-going wave reflects off the ocean surface as a second down-going wave having the same polarity as the first down-going wave and the first and second down-going waves combine substantially in-phase to form a third down-going wave. A source apparatus to accomplish the method is also disclosed. One source apparatus embodiment comprises a device wherein at least part of the device is below the surface of the water and the device is adapted to cause oscillations below the surface of the water, and means for oscillating the device in the water to create an up-going wave and a first down-going wave and the up-going wave has reverse polarity relative to the first down-going wave.

Abstract: The present invention provides a means for holding the components of the device, a means for storing gas under pressure which is maintained separately from the interior of the device until actuating, a means for releasing pressurized gas from the storage device into the interior of the device, a means for actuating the device upon an external event, a means for retaining the pressurized gas in the interior of the device until a desired internal pressure level is achieved and a means for channeling the pressurized gas that is released upon actuation so that the energy supplied propels a pressurized fluid to explosively pass outside of the device through the conduit.

Abstract: A non-explosive acoustic source utilizes the combustion of aluminum and water to generate an acoustic pulse. The operation of the non-explosive acoustic source relies on a water/aluminum reaction to generate a burst pressure. The source may be deployed as a single charge or as one element of a multiple charge array and is configurable to explode at variable depths with variable energy levels. The inherent safety of the non-explosive acoustic source obviates the necessity for auxiliary safety features or procedures to protect against inadvertent explosion. As a result, the non-explosive acoustic source facilitates the implementation of sonic detection systems and reduces the operational costs associated with such systems.

Abstract: Methods and apparatus for attenuating waves in a bore hole, and seismic surveying systems incorporating the same. In one embodiment, an attenuating device includes a soft compliant bladder coupled to a pressurized gas source. A pressure regulating system reduces the pressure of the gas from the gas source prior to entering the bladder and operates in conjunction with the hydrostatic pressure of the fluid in a bore hole to maintain the pressure of the bladder at a specified pressure relative to the surrounding bore hole pressure. Once the hydrostatic pressure of the bore hole fluid exceeds that of the gas source, bore hole fluid may be admitted into a vessel of the gas source to further compress and displace the gas contained therein. In another embodiment, a water-reactive material may be used to provide gas to the bladder wherein the amount of gas generated by the water-reactive material may depend on the hydrostatic pressure of the bore hole fluid.

Abstract: Methods and apparatus for attenuating waves in a bore hole, and seismic surveying systems incorporating the same. In one embodiment, an attenuating device includes a soft compliant bladder coupled to a pressurized gas source. A pressure regulating system reduces the pressure of the gas from the gas source prior to entering the bladder and operates in conjunction with the hydrostatic pressure of the fluid in a bore hole to maintain the pressure of the bladder at a specified pressure relative to the surrounding bore hole pressure. Once the hydrostatic pressure of the bore hole fluid exceeds that of the gas source, bore hole fluid may be admitted into a vessel of the gas source to further compress and displace the gas contained therein. In another embodiment, a water-reactive material may be used to provide gas to the bladder wherein the amount of gas generated by the water-reactive material may depend on the hydrostatic pressure of the bore hole fluid.

Abstract: One embodiment of the invention provides for an apparatus for detecting geophysical energy. The apparatus includes a receiver configured to receive geophysical energy and to convert the geophysical energy into a signal. The apparatus further includes a signal transport device configured to accept the signal and relay the signal to a remote location. The apparatus also includes a fluid conduit configured to contain a pressurized fluid, a production tubing, and an expansible section disposed inline in the fluid conduit. The expansible section is positioned between the production tubing and the receiver, and is configured to expand in response to an increase of fluid pressure within said conduit. When expanded, the expansible section presses against the production tubing and the receiver and thereby causes the receiver to be moved from a first position to a second position.

Abstract: A sound mitigation system and method reduce the transmission of acoustic output from explosions underwater. The system is submerged to bottom terrain of a body of water and has at a series of gas-generating devices providing volumes of gas that are fed to refractory heat resistant tubing assemblies and flexible general tubing assemblies. The heat resistant and general tubing assemblies extend between adjacent gas generating devices and are provided with at least one row of holes to vent bubbles of gas and form a virtually continuous curtain of bubbles rising to the surface of the water between detonating explosives and areas of interest. The curtain of bubbles mitigates the effects of the explosions on marine mammals and endangered, threatened, or protected species within an area adjacent to the explosions.

Abstract: An axially extended downhole seismic source is disclosed. In one embodiment, the seismic source includes multiple pressure storage chambers, each having an inlet valve and an outlet valve. The inlet valve is coupled between the pressure storage chamber and the interior of the drill string, and the outlet valve is similarly coupled between the pressure storage chamber and the annular space around the drill string. A compressible fluid may be provided in the pressure storage chambers, and pistons may be positioned to contact the compressible fluid. For each pressure storage chamber, an inlet piston contacts the compressible fluid and fluid inside the drill string, while an outlet piston contacts the compressible fluid and fluid in the annular space around the drill string. When the outlet valve is closed, the inlet valve can be opened to allow pressure inside the drill string to compress the compressible fluid inside the pressure storage chamber.

Abstract: There is provided an acoustic source especially for use in seismic studies at sea. The acoustic source has a longitudinal axis and sound emitting surfaces adapted to be put into sound emitting movements towards and away from each other by use of a drive unit. The sound emitting surfaces comprise two curved plate members having upper and lower ends essentially symmetrically positioned in relation to the longitudinal axis of the acoustic source, and forming a convex cross section with their respective upper and lower edges converging towards each other. The upper and lower edges of the sound emitting surfaces, respectively, are connected to each other with two corresponding side elements, the side elements each being connected to at least one hinge stretching along at least a part of the length of the source.

Abstract: A marine seismic source for generating acoustic source energy. A housing has a continuous exterior perimeter which is moveable to displace water. Movement of the housing can be accomplished by providing alternating convex and concave exterior surfaces connected with inflection points. The composite shape provides movement inwardly or outwardly, and can be moved with different types of actuators. Piezoelectric elements can be activated to move the housing surfaces and to change the internal housing volume. The resulting pressure pulse provides acoustic source energy useful for the evaluation of subterranean geologic formations and for other purposes.

Abstract: Acoustic source, especially for use in seismic studies at sea, with sound emitting surfaces adapted to be put into sound emitting movements toward and away from each other by use of a drive unit in a known manner, in which the sound emitting surfaces comprise two curved plate members essentially symmetrically positioned in relation to the longitudinal axis of the source, forming a convex cross section with their respective upper and lower edges converging towards each other, and the respective upper and lower edges of the sound emitting surfaces are flexibly connected to two corresponding side elements positioned between them, and that the source comprises a rigid frame for supporting the drive unit, comprising at least two rigid slide rods stretching through the side elements, and that rigid covers are mounted on the slide rods, covering at least the whole side elements, thus forming rigid, covering surfaces with a constant distance between the covers.

Abstract: A system for seismic prospecting by using reflections of acoustic waves and an operation method thereof. Unprocessed raw data from a plurality geophone sensors and other processed data are stored in a storage unit further processing and analysis. The preferred operation comprises four stages, performing test sweeps no and analyzing results thereof (testing stage), determination of control parameters for the spatial distribution of sensor array and data-collection sweeps based on the analysis of test sweeps (parameter-determination stage), performing data-collection sweeps (data collecting stage), and analysis and processing of the data-collection sweeps (data processing stage). Test sweeps and availability of unprocessed raw data allow optimization of the system to achieve maximal resolution and signal-to-noise ratios.

Abstract: A gas gun is provided for generation of an acoustic pulse and subsequent detection of return reflections from the annulus of a well. The system includes a gas gun and a hand-held gas source. The hand-held gas source comprises: a two-part housing forming a chamber for receipt of a small CO.sub.2 gas cartridge commonly used for CO.sub.2 target pistols; means for piercing the gas cartridge and pressurizing the chamber; a coupling for releasable connection to a delivery assembly; a passageway leading from the chamber to the coupling; and a first valve in the passageway for controlling release of gas from the chamber.

Abstract: An apparatus for oscillating a mass at a plurality of selective frequencies includes a source of compressible fluid and a cylinder having a bore filled with the compressible fluid. The cylinder includes a port opening to the bore, the port being connected to the source of compressible fluid. A piston slides in the bore to define a chamber. The piston is operably connected to the fluid mass to oscillate the mass. An average volume of the chamber is adjusted to change the frequency of the oscillating mass.

Abstract: The invention provides apparatus for shaking structures such as fins in a fluid agitator, shaking tables, shaking screens, conveyors, or the walls of bins or hoppers. The apparatus is driven by a hydraulic driving system in which high pressure pulses are generated by repeatedly creating water hammer within a conduit. The high pressure pulses are directed to a chamber where they act against a wall of the chamber to periodically push on the structure. Preferably, the structure is spring-like so that after a high pressure pulse has passed the wall of the chamber is returned to its equilibrium position. In one embodiment of the invention a water hammer pressure pulse is directed into a reinforced hose in contact with a surface to be vibrated. The high pressure pulse causes the hose to expand and move the surface to be vibrated. Water hammer pulses are generated periodically so that the surface is maintained in continuous vibration.

Abstract: A method and apparatus are disclosed for generating intense acoustic pulses by means of the water hammer effect. The method involves generating a water hammer in a conduit by suddenly interrupting a high velocity flow of fluid through the conduit. The kinetic energy of the fluid flowing in the conduit is converted into a high pressure pulse which propagates along the conduit away from the point where the fluid flow was interrupted. The high pressure pulse deforms the wall of the conduit so as to radiate acoustic energy away from the conduit into a fluid medium surrounding the conduit. The relative amount of energy dissipated in the form of mass flow in the surrounding fluid and acoustic energy in the surrounding fluid can be adjusted by changing the characteristics of the conduit wall. The direction in which acoustic energy is radiated into the fluid medium surrounding the conduit can be set by making the conduit wall asymmetrical or by bending the conduit.

Abstract: A subsurface seismic source for generating seismic waves comprises a fluid supply conduit section conducting fluid downward and having a seat for receiving a blocking body transported by said fluid. Said body blocks the fluid through said section when forced against said seat by said mud. At least one piston chamber is arranged adjacent to and connected with said section, has in one end wall at one end an opening to said section above said blocking body when forced against said seat, and comprises a biased piston closing said chamber at the other end and being driven to the corresponding other end wall when the blocking body is forced against said seat. Said blocking body is forced through said seat at a predetermined mud pressure level, thereby releasing said piston, the piston colliding against the one end wall and generating seismic waves.

Abstract: An acoustic wave energy generator comprises a body having an internal gas-pressurisable first chamber 1 adjoining a second chamber 2 into which a liquid is introduced to cover a vibratable means 4 which may be a flexible diaphragm and is mounted on the second chamber so as to close an associated opening 5 in the second chamber. After the first chamber 1 is pressurised with a first gas a common closed opening between the chambers is opened to cause communication between the chambers 1,2 to permit a shock wave emanating from the first chamber to impinge on the liquid. As a result, the vibratable means 4 is caused to vibrate so as to produce acoustic wave energy in response to the impingement of the shock wave on the liquid. By using different liquids and/or different heights of liquids in the second chamber the generator may be tuned to provide acoustic wave energy with a relatively narrow chosen frequency range or within a chosen substantially single frequency.

Abstract: A human-portable geophysical energy source is disclosed having an earth-coupling element, a means for providing seismic energy operably connected to that earth-coupling element, a lower container and an upper container connected to the means for providing seismic energy, a framework that minimizes vibrations of the liquid by keeping the upper and lower containers inflexible when they are completely filled with liquid, and a hydraulic pump for filling and removing liquid from the containers. The lower container is located spatially between the earth-coupling element and the means for providing seismic energy. The upper container is located spatially above the means for providing seismic energy. The liquid provides mass to impart energy through the earth-coupling element and to maintain coupling with the earth.

Abstract: Seismic signals are generated in an earth formation at a selected point in a wellbore by apparatus insertable in the wellbore at the distal end of a tubing string. The apparatus is adapted to receive hydraulic pressure fluid from the tubing string for deploying contactor pads in engagement with the wellbore wall and for transmitting seismic signals through the pads to the earth formation. In one embodiment a hydraulic piston is directly connected to linkage for the contactor pads and an oscillatory signal is imposed on the piston for generating vibratory seismic signals. In a second embodiment, a compressed gas-driven impactor is moved to and held in a cocked position by a hydraulically-actuated setting and latching mechanism. Hydraulic control valves and electrical operating circuits are disposed on the apparatus and may be controlled from the surface by way of a wireline cable extending through the tubing string.

Abstract: A displacement amplifier interconnects a piezoelectric actuator with a displacement member and comprises respective bellows members of differential diameter defining first and second expansible chambers which are liquid filled and respond to linear displacement of a stack of piezoelectric disks to provide an amplified linear displacement to the displacement member. The transducer is particularly useful as a signal transmitting or receiving transducer for acoustic wave generation or measurement for wellbore logging tools.

Abstract: Disclosed is an apparatus for generating seismic waves in a well bore, which apparatus includes a tubular expandable and contractible outer anchor wall, a seslf-contained anchor setting hydraulic system to expand the anchor into anchored position in the bore hole, a self-contained vibrator hydraulic system operable to cycle pressure impulses to the interior of the tubular expandable and contractible outer anchor wall effective to produce and radiate seismic waves, a cable including electric lines for locating the apparatus in the well bore, and switch means at the surface for controlling the operation of the apparatus. The apparatus is useful for geophysical investigation including vertical seismic profiling and cross hole tomography.

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: 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: Apparatus including transportation structure for generating elliptically polarized shear waves in soft earth medium. A suitable carrier includes a jack assembly for transporting shear wave apparatus that includes a telescoping tube for earth engagement. The shear wave apparatus, including a major or lower reaction mass and a passive top reaction mass, is raised and lowered by the jack assembly into operative position while the energy-coupling telescoping tube is extendably forced into an earth medium so that, during shear wave generation, the vibration source or reaction mass is continually imparting shear wave energy into the progressively extending telescoping tube to effect continual energy coupling into the surrounding earth medium. The reaction mass is driven by a plural hydraulic actuator system that imparts elliptically polarized vibration to the telescopic tube which, in turn, imparts elliptically polarized shear waves into the surrounding earth medium.

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.