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: A method of and a system for remotely controlling an adjustable, electrodeless arc discharge acoustic pulse transducer for borehole and underwater operations using high-energy arc discharges to generate high power seismic and acoustic pulses capable of being easily and remotely adjusted in time duration and magnitude such that they can be customized to create waveforms of preferred shapes. The transducer has an insulating ceramic barrier which contains a biconical aperture separating two bodies of electrolyte through which the two zones of liquid make contact and electrically adjustable circuits for switching supplemental amounts of stored electrical energy into the arc discharge circuit at successively delayed time intervals to lengthen the arc discharge current pulse to create the desired waveform shape for detecting variations in the geological features of the formations being probed or for use in ocean acoustic or sonar applications.

Abstract: A hydrogen-oxygen acoustic logging device is provided for generating acoustic waves for logging a subsurface formation when arranged in a borehole through the formation. The device is electrically driven for electrolyzing water to a gaseous hydrogen-oxygen mixture and for firing the gaseous mixture for generating the waves. The device comprises an inflatable compartment to be inflated by the gaseous hydrogen-oxygen mixture. The device further comprises a housing having an outer wall facing and closely fitting to a borehole wall portion, and provided with a recess. The recess contains the inflatable compartment and, when arranged in logging position against said borehole wall portion, defines a substantially closed wave generating chamber.

Abstract: A method of use of a logging tool (1) including a directional emission device (4) and/or reception device (R1, R2) and the achieving of several series of loggings while modifying between each series the orientation of the directivity diagrams. At least one first series is performed by orienting the directivity diagrams towards the top or the wall of a reservoir zone crossed through by the well bore, for example. At least one second series is carried out by orienting the directivity diagrams towards the opposite direction, for example. The recordings are then combined, and the reflected arrivals, which are generally concealed by casing waves, can be easily seen. This facilitates the locating of further discontinuities. The directional selectivity of the emissions and/or the receptions is, for example, obtained by positioning a cover fitted with a window (5) around emitting and/or receiving transducers. The method can be applied to loggings in horizontal well bores, for example.

Abstract: A focused acoustic transducer for use with a borehole televiewer wherein the transducer is provided with a concaved surface designed to focus the acoustic energy and reduce the energy present in the side lobes of the near field.

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: A mud pulser for measurement-while-drilling applications is disclosed which employs piezoelectric transducers to provide for variations in the mud flow through a mud pulser sleeve. The piezoelectric transducers used in the mud pulser are comprised of two piezoelectric elements bonded together in a bender bar transducer configuration, thin metallic sheets to improve the rigidity of the transducer and to protect the ceramic material and electrodes from the effects of abrasive drilling fluid, and simplified mounting means.

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 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 for detecting the presences of fractures in a subsurface formation being penetrated by a drill bit during drilling. Teeth on the drill bit act as individual seismic sources, generating both shear wave energy and compressional wave energy. As the drill bit passes through a formation, the shear wave energy generated by the bit propagates along the formation in a waveguide mode between the adjacent formations. As the shear wave signal passes through a fractured zone of the formation, two shear wave signals are generated, each polarized in relationship to the orientation of the fractures in the formation. As the polarized signals propagate along the formation, secondary shear wave signals are generated which return to the surface and are detected by appropriate sensors. The sensors have a plurality of detectors in order to detect the polarity or direction of particle motion cuased by the polarized wave, providing information that a fracture zone exists in the subsurface.

Abstract: A seismic source for use in a borehole (10) comprises a resonant system (26) which is excited at its resonance frequency while said resonance frequency is caused to vary in controlled manner, thereby performing a frequency sweep. To this end, the pressure inside the enclosure (32) containing the reaction mass (30) of the resonant system (26) is raised to a given initial static pressure by means of a high pressure unit (60), after which the pressure inside the upper chamber (38) of the enclosure (32) is caused to vary according to a substantially sinusoidal law, by means of an electrically controlled valve (52) fed from a low pressure unit (46), while the static pressure is caused to vary regularly via a constriction (74).

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: A transducer for an acoustic logging tool includes a liquid-filled cavity formed by a substantially rigid housing portion of the tool and having a resilient barrier member disposed between liquid in the wellbore and the liquid in the cavity. A magnetic field extends transversely through the cavity and a member, which may comprise a rigid plate, a flexible member or a quantity of electrically conductive liquid trapped between flexible membranes, is disposed in the cavity for movement normal to the magnetic field. A voltage is generated in response to movement of liquid in the cavity which is proportional to the velocity of the plate or member, or the velocity of the conductive liquid, the length of the conductive path and the intensity of the magnetic field in accordance with the principles of the Lorentz force.

Abstract: A piezoelectric seismic vibrator is disclosed which utilizes a hydraulic system to amplify the longitudinal displacement which results from the application of a voltage to a stack of piezoelectric elements. In each disclosed embodiment of the present invention, a stack of piezoelectric elements is mounted so as to bear upon a power piston which in turn acts upon a high bulk modulus substantially incompressible body of fluid, such as mercury. A drive piston is provided having a cross-sectional area which is smaller than the area of the power piston and the pressure within the fluid system acts to amplify the longitudinal displacement of the piezoelectric elements. The movement of the drive piston is then coupled mechanically or fluidically to the earth to generate seismic waves therein. In one depicted embodiment of the present invention each stack of piezoelectric elements is disposed within a fluid filled chamber which is pressurized by means of communication with the borehole fluids.

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: A pack-off locking means for use in downhole geological seismic work. An upper and lower endcap rigidly connected together by a inelastic vertical member which is adapted to hold a seismic energy source. The endcaps have sealing means attached thereto for isolating a cylindrical section of the well borehole, thus, forming a sealed chamber wherein the seismic energy source contained therein transmits acoustical energy in a mostly horizontal and omni-directional plane into geological formations of interest. Minimal acoustical energy is transmitted into the borehole vertical fluid column because the seal-off means prevents communication thereto. Means for pressurizing the chamber formed by the pack-off means and for measuring the pressure thereof.

Abstract: A drill string in a fluid-filled borehole acts as a waveguide for an extensional wavefield that is generated in the drill string when it is excited by the vibrations of a drill bit secured to the lower end of the drill string. The waveguide acts as a distributed acoustic energy source which initiates head waves in the surrounding formation. The head waves are detected at one or more discrete locations near the surface of the earth. The extensional wavefield is detected by a sensing means mounted at the top of the drill string. The detected head waves are cross-correlated with the detected extensional waves to create a cross-correlogram which may be displayed.

Abstract: A sonde is secured to the end of an electrical cable and is inserted is a bore hole by means of the electrical cable. The sonde has a transmitter and receiver. The other end of the cable is secured to apparatus on the surface, and the apparatus includes means for forming a signal transmitting it through the cable to the transmitter, the transmitter emitting the signal from the sonde, that signal bouncing off of the wall of the bore hole and then back to the receiver. The signal is then sent from the receiver through the cable to the apparatus on the ground. That apparatus also has means for recording the results of the signals so formed and mainpulated. The transmitter and the receiver in the sonde are placed together, not more than one half of the wave length of the signal, and to a spacing as small as zero, with transmitter and receiver effectively in one location.

Abstract: A downhole seismic shear wave source is used to generate seismic shear waves a downhole environment. At least one double headed piston rod with a third piston on the center of the rod slides laterally in the downhole tool. Each end piston head is connected to a rolling diaphragm that is secured at its edges around the periphery of the piston receiving cavity. The cavity is filled with a low viscosity non-conducting oil. A servovalve is connected to opposite sides of the center piston head to produce low frequency vibration of the source generator. A veed target rod extends between the end piston heads, past a pair of eddy current transducers (ECTs) to monitor movement of the generator and provide feedback control to the servovalve. A second downhole seismic shear wave source contains a continuous vibrator ring replaces the diaphragm/oil system and a linear variable differential transformer (LVDT) replaces the eddy current transducers as the feedback signal generator.

Abstract: An apparatus for forcing a member or device, such as a sample tube or seismic or geological instrument, through a material such as soil along a selected line of action. The apparatus includes a derrick with first and second plates mounted thereto, the second plate having a locking dog extending through a hole therein for engaging a collar set in material, and the first plate being provided with a hydraulic cylinder or other device for forcing the member through the material. The first plate is also provided with an extruder head for releasably mounting the sample-containing sample tube thereto, and the hydraulic cylinder is provided with a plunger releasably mounted to the ram thereof, for extruding the sample from the sample tube.The collar positively engages the material to provide an apparatus for transmitting the reactive forces resulting from forcing the member through the material to the material.

Abstract: An acoustic signal transmitter for well logging tools and the like comprising a housing having a generally rectangular opening formed therein and defining a fluid filled cavity in which a compliant sheet transmitter member is disposed and is provided in a relaxed condition with a curvature. Opposite ends of the transmitter member are connected to piezoelectric actuators which are responsive to an electrical signal to elongate to stretch the sheet into a generally planar state to generate a pressure pulse in the cavity for transmission through a fluid filled borehole to a formation for, preferably, measuring the shear wave velocity in the formation material.

Abstract: A low impedance acoustic source suitable for used in down-hole well logging includes a mechanical transformer for impedance matching of the source to the surrounding environment. Elliptically shaped flexible beams are positioned along the long axis of an ellipse, and a pump is oriented along the long axis of the ellipse for driving the flexible beams. In a preferred embodiment the pump comprises first and second stacks of transducers which engage the flexible beams at opposing ends with the two stacks of transducers operating in a push-pull mode of operation. Rigid extension at opposing ends of the flexible beams function as levers in translating the motion of the transducers to the flexible beams. A rigid support rod is positioned along the long axis of the ellipse in engagement with the rigid extensions at fulcrum points, and an adapter associated with each stack of ceramic transducers engages and drives the rigid members about the fulcrum point.

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: The invention furnishes an electrodynamic transducer head for a non-destructive testing of workpieces with electrically conductive surfaces by way of ultrasound. A magnet system is employed for generating of a static or a low-frequency magnet field, and at least one transducer coil is disposed at the front face of the magnet system disposed toward the workpiece. The transducer coil is furnished on the side toward the workpiece with a wear-resistant layer, and the transducer coil exhibits between itself and this front face of the magnet system an intermediate part with an insulating layer, which is solidly connected with the front face and with the coil adjoining at the insulating layer.

Abstract: An electromagnetic source or sources in a sonde in a well bore is caused to emit electromagnetic forces into the well casing. The electromagnetic forces cause displacement of the casing, inducing acoustic waves. The acoustic waves may be either P-waves or S-waves, depending on the type of electromagnetic source used. The response of earth formations to the acoustic waves, once detected, is used to detect fractures in the formations.

Abstract: An acoustin transducer system for a borehole televiewing apparatus is set forth. In the preferred embodiment, a ceramic circular disc is used and is divided by grooves selected thereon into a set of N concentric rings where N is a whole number integer. Each ring has its own associated transmitter and they are fired in a controlled sequence. Each ring operates as a receiver, and they form output signals which are amplified and controlled delay at the respective delay lines, the several output signals are summed. This assures that the illuminated regions of the borehole is in focus and has a greater depth of field. And a method is also described whereby multiple simultaneous electronically formed acoustic beams are utilized in a differential mode to achieve high spatial resolution in time of flight measurements.

Abstract: A monopole transmitter for a sonic well tool includes an axial tube, a piezoceramic cylinder surrounding the axial tube, an endcap disposed at each end of and firmly contacting the cylinder, and an apparatus for holding the endcaps firmly against the axial tube. The endcaps firmly contact the axial tube without simultaneously contacting an upper bulkhead. The apparatus may include spring washers disposed between the bulkhead and at least one endcap, or it may include a spring disposed between a nodal mount and each endcap. A nodal mounting tube may be disposed around the axial tube, a ring being disposed at each end of the nodal mounting tube, each ring being disposed outside of the cylinder, the apparatus including a spring disposed between each ring and an endcap outside of the cylinder for biasing the endcaps in tension against a ring thereby holding each endcap firmly in contact against the axial tube.

Abstract: A sonic well tool includes a transmitter array, including at least one monopole transmitter and at least one dipole transmitter, and a receiver array for receiving sonic pressure wave signals from a surrounding borehole formation. A first attenuation and delay apparatus is positioned above the receiver array and a second attenuation and delay apparatus is positioned below the receiver array in the sonic well tool. The first attenuation and delay apparatus includes an attenuation member comprising a plurality of interleaved rubber and metal like washers for attenuating compressional and flexural waves propagating along a metal, center support rod to the receiver array and an inner housing comprising a bellows section having a corrugated shape and a thin transverse dimension for delaying the propagation of compressional and flexural waves along the inner housing to the receiver array.

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: An advanced downhole 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: Method and apparatus for determining the precise location of a drill bit tip relative to specified locations on a workpiece in precision automatic machining operations. Elastic waves are induced in a drill shank, guided through the shank to the drill bit tip and couple to the surrounding workpiece material in contact with the tip of the drill bit. Elastic wave sensors are disposed in elastic wave transmitting relation with the workpiece to detect the induced elastic waves. The precise location of the drill bit tip is determined by computing the propagation time of elastic waves from the drill bit tip to each of the respective sensors. In one embodiment, elastic waves are induced with contactless electromagnetic coupling via a magnetostrictive transduction technique. Other techniques for inducing elastic waves in a drill bit are described.

Abstract: The quadrupole shear wave logging device of this invention includes a logging sonde, means for generating a quadrupole shear wave in the earth formation surrounding a borehole containing fluid, and means for detecting in the fluid the refraction of the quadrupole shear wave. In the preferred embodiment, the generating means comprises four similar sectors of a hollow piezoelectric cylinder. The four cylinders are polarized radially. The four sectors are so connected to the sonde that they are in the form of a split cylinder coaxial with the sonde axis. Electrical pulses of similar waveforms are applied across the inner and outer cylindrical surfaces of each sector to vibrate the four sectors. The electrical pulses are of such polarities that, during their initial motions of vibration, two oppositely situated sectors are caused to move outward and the remaining two oppositely situated sectors to move inward substantially simultaneously.

Abstract: A method and apparatus for geophysical exploration wherein a seismic wave is passed through a bore hole so at to sequentially detonate a plurality of explosive charges disposed within said bore hole at spaced intervals. A preselected seismic wave magnitude represented by a stored voltage is compared with signals generated by electro-acoustic sensors associated with each charge. When the magnitude of a seismic wave in the bore hole equals the preselected magnitude, a voltage stored on a capacitor discharges into a detonator. Means are provided for varying the stored voltage representing the preselected magnitude from the surface of the bore hole and for detonating any unexploded charges which may after the initial seismic wave passes through the bore hole. A firing circuit is armed substantially simultaneously with the initiation of the seismic wave in the bore hole. The firing circuit is armed for only approximately 0.1 to 0.5 seconds thereby preventing late detonation which destroys seismic data.

Abstract: An acoustic wellbore logging tool transducer formed of a composite plate member having at least one plate of a magnetostrictive material which responds to a magnetic field to elongate or contract to effect displacement of said plate member within a cavity formed in a housing section of the logging tool. The logging tool cavity may be exposed to wellbore fluid in direct contact with the plate member whereby acoustic pressure pulses may be delivered directly to the wellbore fluid by the transducer element. Spaced apart electromagnets are disposed in the housing section on opposite sides of the cavity for effecting controlled displacement of the plate member to generate acoustic waves in a liquid-filled wellbore.

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 vibrator and method for transmitting seismic signals into the earth to obtain data on various subsurface characteristics. The vibrator is driven with piezoelectric transducers, 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: Method and apparatus for converting tube waves into body waves downhole for seismic exploration are disclosed, comprising a rotary valve tube wave source for producing swept frequency tube waves that are injected into a tubing or wellbore. The tube waves are converted to body waves by an elongate tube wave converter located at a selected position downhole. The tube wave converter comprises an elongate body that preferably substantially fills the wellbore or tubing and has a preferred shape in order to convert efficiently the tube waves to body waves at the selected position downhole.

Abstract: Downhole conditions in wellbores such as fluid pressure, temperature and flow conditions during drillstem testing or during wellbore stimulation or fracturing processes are transmitted through sensing and signal conversion circuits to axial or torsional wave vibrators secured to a drillstem or tubing string in the borehole for generating stress wave vibrations in the drillstem or tubing string for transmission to a point at or near the earth's surface. Accelerometers and/or strain gauges are mounted on the stem or tubing at a point near the earth's surface for sensing the torsional, axial or bending vibrations and converting the vibratory signals to signals for receipt and recording and correlated with the signals being transmitted from the borehole. The system includes an axial compression wave generator comprising a solenoid energized oscillator hammer member disposed on a sub which may be interposed in the drillstem.

Abstract: A method and apparatus for geophysical exploration wherein a seismic wave is passed through a bore hole so as to sequentially detonate a plurality of explosive charges disposed within said bore hole at spaced intervals. A preselected seismic wave magnitude represented by a stored voltage is compared with signals generated by electro-acoustic sensors associated with each charge. When the magnitude of a seismic wave in the bore hole equals the preselected magnitude, a voltage stored on a capacitor discharges into a detonator. Means are provided for varying the stored voltage representing the preselected magnitude from the surface of the bore hole.

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: The shear velocity of a region of an earth formation may be determined by a logging tool insertable in a wellbore penetrating the formation which includes plural transducers for generating compressional waves for transmission through the formation as shear wave between the signal generating transducers and an array of signal receiving transducers spaced from the signal generating transducers. The transducers may be plural in number and arranged to effect impingement of the compressional wave on the borehole wall at an angle of incidence preferably in the range of 35.degree. to 75.degree. to a normal to the wall surface. The transducer array is controlled so that a significant portion of the compressional wave energy transmitted through liquid in the wellbore is converted to shear waves at the wellbore wall, which shear waves constructively interfere to develop a torsional wave propagating along the wellbore between the transducers and the receiver elements.

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: A blasting system wherein the actuation of detonators at a plurality of blast holes is controlled by firing one or more test blasts and, at each blast hole, monitoring the resulting shock wave to derive data which is used to determine time delay criteria for the blast holes.Each detonator includes a shock sensitive device which detects the shock wave. Each detonator has on-board signal processing capability and optionally is connected to a central control computer.

Abstract: A method is provided for improving the coefficient of transmission to geological formations of the energy generated by the firing of a seismic source lowered inside a well or borehole and a device for implementing same. A zone of the wall containing the seismic source is defined by confinement so as to prevent the propagation along the well, outside the confined zone, of the energy generated therein by the seismic source, when fired. The confinement is achieved by closing off the wall on each side of the seismic source. Two expandable members are used disposed in the wall on each side of the source and each comprising for example an elastomer sheath, an annular piston whose movement causes expansion of the sheath and hydraulic means for moving the piston.

Abstract: A method, system and apparatus for producing powerful seismic energy impulses by implosion of an imploding free piston positioned in a container which is adapted to be lowered down into a well in the earth to facilitate the collection of well surveying information about the geological formations of the earth in the vicinity of the well. Holding means maintain the imploding free piston in an initial position or quiescent state, trigger means suddenly release the holding means to cause the free piston to accelerate rapidly from its quiescent state thereby producing a powerful impulse by implosion, damping means arrest the movement of the imploding free piston, and operating means return the imploding free piston to its initial position after completion of its rapid acceleration and damped deceleration. After the imploding free piston is returned to its initial position, the apparatus may be triggered again, as desired, to produce additional powerful impulses by implosion.

Abstract: The quadrupole shear wave logging device of this invention includes a logging sonde, means for generating a quadrupole shear wave in the earth formation surrounding a borehole containing fluid, and means for detecting in the fluid the refraction of the quadrupole shear wave. In the preferred embodiment, the generating means comprises four similar sectors of a hollow piezoelectric cylinder. The four cylinders are polarized radially. The four sectors are so connected to the sonde that they are in the form of a split cylinder coaxial with the sonde axis. Electrical pulses of similar waveforms are applied across the inner and outer cylindrical surfaces of each sector to vibrate the four sectors. The electrical pulses are of such polarities that, during their initial motions of vibration, two oppositely situated sectors are caused to move outward and the remaining two oppositely situated sectors to move inward substantially simultaneously.

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: 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.]. .Iadd.longitudinal .Iaddend.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.