Abstract: Seismic shear-wave survey systems and methods that employ inclined borehole pairs with directional detonations. If the boreholes have substantially equal inclinations in opposite azimuthal directions, the resulting signal traces can be combined to isolate shear wave energy contributions, thereby offering potentially enhanced resolution and reduced-complexity interpretation. The boreholes may be cased to ensure repeatability for, e.g., monitoring of reservoir fracturing, treatments, and/or drainage. The directional charges may be immersed to improve coupling of seismic energy into the formation.

Abstract: According to embodiments, a sensor includes a structure body, a container, a liquid and a sensing unit. The structure body includes a supporter, and a film unit. The film unit includes a first region. The first region includes a first end portion supported by the supporter, and a first portion being displaceable. The film unit includes an opening. The container is connected to the structure body. A first space is defined between the film unit and the container. The liquid is provided inside the first space. The sensing unit senses a displacement of the first portion accompanying a displacement of the liquid.

Abstract: An arrangement for providing explosive charging and a plug into a bore hole, wherein a hose comprising at least one first conduit is introduced into said bore hole. Also explosive material is introduced to an outlet of said first conduit and thereby into said bore hole. In addition a plug is introduced into said bore hole by the help of said hose. The plug has a diameter, the size of which is configured to be manipulated after or during introducing into said bore hole at a certain depth so that after said introducing the diameter of the plug is larger than before said introducing and so that the surface of the plug after manipulating the size of diameter essentially make a physical contact with the bore hole surface. The plug is introduced by said hose in a releasable manner so that after or during the manipulation of the plug diameter size the plug is configured to be released from the hose and to stay in said bore hole essentially at said certain depth.

Abstract: The present invention pertains to a system and method for accelerating a mass using a pressure produced by a detonation, where the mass is accelerated over a movement range using a detonation of a pressure wave generator that produces a pressure within a coupling component that is applied to a piston having a surface area that produces a resultant force, where the acceleration of the mass determines the resulting force. The resulting force may be directed vertically and perpendicular to a target media to conduct an acoustic wave into the target media. The system may be configured to direct the resulting force horizontally and parallel to a target media to conduct a plane shear wave into the target media. Two systems may be configured to direct two resulting forces horizontally and parallel to a target media to conduct a spherical shear wave into a target media, where the two resulting forces are directed in opposite directions and separated by some distance.

Abstract: A method for determining position of a wellbore in the Earth's subsurface includes actuating a plurality of seismic energy sources each disposed at a known geodetic position. Seismic energy from the sources is detected at a selected location along the wellbore. The geodetic position at the selected location is determined from the detected seismic energy. A corresponding method includes actuating a seismic energy source at a selected position within the wellbore. The seismic energy is detected at a plurality of known geodetic positions. The geodetic position of the source is determined from the detected seismic energy.

Abstract: Shock waves produced during electro-hydraulic drilling can be reflected into a rock body where the reflected shock waves are converted from compression waves to tension waves, which are more efficient at breaking down the rock body. A system configured for electro-hydraulic drilling where shock waves produced during drilling are reflected into the rock body includes two electrodes and a shock wave reflector disposed at an electro-hydraulic drill head. The two electrodes are configured to (1) facilitate formation of a spark along a spark path spanning the two electrodes and (2) facilitate a pulse of electricity being passed through the spark to form a primary shock wave emanating from the spark path. The shock wave reflector is configured to reflect a portion of the primary shock wave such that the reflected shock wave is concentrated to a focal region within the rock body.

Abstract: The present invention provides for pulsed powered drilling apparatuses and methods. A drilling apparatus is provided comprising a bit having one or more sets of electrodes through which a pulsed voltage is passed through a mineral substrate to create a crushing or drilling action. The electrocrushing drilling process may have, but does not require, rotation of the bit. The electrocrushing drilling process is capable of excavating the hole out beyond the edges of the bit with or without the need of mechanical teeth.

Abstract: A system and method for managing a well site having a subterranean formation. The method comprises determining a first spectral attenuation of a first seismic wave measured from a first location, determining a second spectral attenuation of a second seismic wave measured from a second location, determining a reservoir attenuation anisotropy from a comparison of the first spectral attenuation to the second spectral attenuation, and determining at least one fracture parameter of the subterranean formation from a comparison of the first seismic wave to the second seismic wave.

Abstract: Shock waves produced during electro-hydraulic drilling can be reflected into a rock body where the reflected shock waves are converted from compression waves to tension waves, which are more efficient at breaking down the rock body. A system configured for electro-hydraulic drilling where shock waves produced during drilling are reflected into the rock body includes two electrodes and a shock wave reflector disposed at an electro-hydraulic drill head. The two electrodes are configured to (1) facilitate formation of a spark along a spark path spanning the two electrodes and (2) facilitate a pulse of electricity being passed through the spark to form a primary shock wave emanating from the spark path. The shock wave reflector is configured to reflect a portion of the primary shock wave such that the reflected shock wave is concentrated to a focal region within the rock body.

Abstract: An acoustic energy source for imparting acoustic energy into the Earth's subsurface includes an electrically driven transducer coupled to a source of swept frequency alternating current. A tunable Helmholtz resonator is disposed proximate the transducer. In one example, the resonator has a tuning device configured to maintain a resonant frequency substantially equal to an instantaneous frequency of the alternating current. The tuning device includes an actuator coupled to a sleeve, wherein the sleeve is disposed over selected numbers of openings in a wall of a tube on the resonator. The transducer and the resonator are disposed in a wellbore drilled through rock formations. The wellbore has a plurality of layers of fluid therein, each layer thereof having a different density and/or viscosity.

Abstract: A system and method for performing a fracture operation on a well site having a subterranean formation with a reservoir therein. The method involves measuring at least one seismic wave before and after stimulating the subterranean formation, comparing the seismic waves measured before the stimulation of the subterranean formation to the seismic waves measured after stimulation of the subterranean formation, and determining at least one fracture parameter of the subterranean formation from the compared seismic waves.

Abstract: A method of steering a drilling operation of a well using acoustic measurements. The method includes obtaining, using a central processing unit (CPU), a clean-wet matrix line for the well, where the clean-wet matrix line includes a number of normal compressional values, obtaining, using the CPU, the acoustic measurements from at least one logging while drilling tool at a current depth of the drilling operation, where the acoustic measurements include a compressional to shear velocity ratio and a delta-T compressional measurement, and determining, using the CPU, a current phase of the drilling operation by comparing the acoustic measurements to the clean-wet matrix line. The method further includes, in response to determining that the current phase is not a target phase, generating an updated well trajectory for steering the drilling operation toward the target phase and adjusting the drilling operation using the updated well trajectory.

Abstract: A Seismic source comprising an actuator having a rotary part (104) and a reciprocative part (105), conversion means (109) in the form of corrugated surfaces to convert a rotation of the rotary part (104) into a reciprocal movement of the reciprocative part (105), and a vibrator body (106) that is connected to the reciprocative part (105) of the actuator by means of a spring (107).

Abstract: The present invention provides a method and apparatus for seismic data acquisition. One embodiment of the method includes accessing data acquired by at least two particle motion sensors. The data includes a seismic signal and a noise signal and the at least two particle motion sensors being separated by a length determined based on a noise coherence length. The method may also include processing the accessed data to remove a portion of the noise signal.

Abstract: In one aspect of the present invention a method has steps for taking downhole measurements. A network integrated into a downhole tool string in a well bore may be in communication with a downhole sensor, the downhole sensor having a downhole clock that may be in communication over the network with and synchronized with a top-hole clock source. A signal source may be within a transmitting distance of the downhole sensor and may be activated. The downhole sensor records signals from the signal source at a recorded time when the network is disconnected from the top-hole clock source. When the network is reconnected, the downhole clock and the top-hole clock source are re-synchronized. The clock drift that occurred during the disconnection may be calculated. The recorded time may be adjusted to reflect what it would have been if the downhole clock had been synchronized with the top-hole clock source.

Abstract: A sonic drilling apparatus having a work piston within a cylinder chamber to provide a vibratory force through the alternate application of fluid under pressure into the bore above and below the piston in a manner that the piston will be forced to reciprocate within the bore. The cylinder chamber includes an inlet gallery to allow fluid under pressure to pass into the bore above a first face of the work piston and an exhaust gallery to allow fluid to escape from the bore below the second face of the work piston. A relief bypass is provided to prevent excessive build up of pressure in the bore during the reciprocating movement of the work piston.

Abstract: A method of conducting seismic evaluation of a subterranean formation wherein a rigid, elongate member having a first end and a second end is positioned such that the first end of the elongate member is at a point on the earth's surface, imparting an impulsive force to the elongate member to urge the member into the earth, the positioning of the rigid member and the impulsive force being sufficient to generate and propagate primary seismic waves into the subterranean formation and positioning one or more seismic wave detectors on the surface of the earth to detect and receive reflected seismic waves from the subterranean formation.

Abstract: An underground drilling method and apparatus generates intense pressure pulses at a location at the surface. The pressure pulses propagate down through a drill string to a drill bit. The pulses may be generated by creating water hammer in flowing drilling mud. Intensity of the acoustic pulses is increased in the bit nozzles. Vigorous pulsing of the fluid exiting the bit nozzles results in better cleaning of the hole bottom and faster drilling. The pulses may be used to drive the operation of various down hole tools. One type of tool has multiple pistons arranged in series. High pressure pulses move the pistons to generate strong mechanical vibration in the drill string. Vibration of the drill string may also reduce the friction between the drill string and the hole, resulting in lower torque requirements.

Abstract: A method of seismic data processing is described in which a particular wavelet is selected from a plurality of wavelets as being most characteristic of a received seismic signal. A subtracted signal can be determined by subtracting a weighted signal of the particular wavelet from the received signal. From the subtracted signal, an additional particular wavelet can be chosen. The process of subtracting a signal and determining an additional particular one of the plurality of wavelets can be repeated until a criterion is met. The method can be repeated at several depths. The resultant spectral analysis can be used to determine, for example, an absorption coefficient.

Abstract: A system and method for acquiring seismic data are disclosed. The system comprises a controller for causing the generation of a seismic signal, where the controller has a first clock used for time-stamping a record of the generated seismic signal. A seismic receiver is deployed in a wellbore so as to detect the generated seismic signal. An atomic clock is disposed in or with the seismic receiver for time-stamping a record of the detected seismic signal. The atomic clock is synchronized with the first clock prior to being placed downhole.

Abstract: An underground drilling method and apparatus generates intense pressure pulses at a location at the surface. The pressure pulses propagate down through a drill string to a drill bit. The pulses may be generated by creating water hammer in flowing drilling mud. Intensity of the acoustic pulses is increased in the bit nozzles. Vigorous pulsing of the fluid exiting the bit nozzles results in better cleaning of the hole bottom and faster drilling. The pulses may be used to drive the operation of various down hole tools. One type of tool has multiple pistons arranged in series. High pressure pulses move the pistons to generate strong mechanical vibration in the drill string. Vibration of the drill string may also reduce the friction between the drill string and the hole, resulting in lower torque requirements.

Abstract: A system and method for acquiring seismic data are disclosed. The system comprises a controller for causing the generation of a seismic signal, where the controller has a first clock used for time-stamping a record of the generated seismic signal. A seismic receiver is deployed in a wellbore so as to detect the generated seismic signal. An atomic clock is disposed in or with the seismic receiver for time-stamping a record of the detected seismic signal. The atomic clock is synchronized with the first clock prior to being placed downhole.

Abstract: A shaftless acoustic source is disclosed having a solenoid, a bullet and driving electronics. The bullet, which is positioned inside the solenoid's coil, can be accelerated by a magnetic force generated when a current pulse is applied to the coil. Acoustic energies are generated upon the impact of the bullet with an object, such as a borehole wall. This impact force can be described by the Hertzian Contact Theory (also referred to herein as Hertzian Theory) as a point of normal force with a time function similar to a half period sine function. A retraction device may be used to retract the bullet back into the solenoid after firing.

Abstract: An acoustic system and method for monitoring a hydrocarbon reservoir. Wellbore tube wave energy may be created by natural or ambient sources or tube waves may be excited intentionally. Wellbore tube wave energy is converted to seismic body wave energy at minor borehole obstructions or irregularities. Each obstruction or discontinuity position along the borehole has an associated unique waveform source coda that may be measured for processing the body waves radiated into the earth formation surrounding the well bore. A plurality of sensors detects the radiated seismic energy after the seismic body wave energy has transited intervening earth formations. The system may be employed for permanent monitoring of mineral resources and resource management. Measurements of reservoir characteristics may be acquired at many different times over the productive life of a reservoir.

Abstract: The present invention provides an ultrasonic and sonic mechanism of deep drilling (USMOD) that is driven by a vibrating actuator and operates in a similar manner to the gopher with regards to drilling debris removal. The actuator induces vibration in the form of a hammering actuation. The mechanism consists of a penetration bit with a diameter that is the same or larger than the actuator. The embodiment of the invention that is disclosed herein emulates a gopher. This ultrasonic gopher is lowered down into the produced borehole, cores the medium, breaks and holds the core, and finally extracts and deploys the core.

Abstract: A valving system is disclosed which generally comprises a body including an inlet and an outlet where the inlet is disposed in fluid communication with a fluid flow passage and the outlet is disposed in fluid communication with a pressurized fluid member, the body further defining an internal bore in which is slidably disposed a piston moveable between a first and a second position such that fluid communication between the fluid flow passage and the fluid flow member is established when the piston is disposed in the first position but not in the second position, an apparatus and to move the piston from the first position to the second position so as to interrupt fluid flow from the fluid flow passage to the fluid member.

Abstract: Suction pressure pulses are generated within a borehole by closing a valve that interrupts the flow of a drilling fluid (e.g., drilling mud) circulating through one or more high velocity flow courses within the borehole. In one embodiment in which the suction pressure pulses are applied to improve the efficiency of a drilling bit, the valve interrupts the flow of drilling mud directed through the bit and thus through high velocity flow course(s) disposed downstream of the bit. Arresting flow of the drilling mud through the high velocity flow course(s) generates suction pressure pulses of substantial magnitude over a face of the drill bit. The suction pressure pulses provide a sufficient differential pressure that weakens the rock through which the drill bit is advancing and also increase the force with which the drill bit is being advanced toward the rock at the bottom of the borehole.

Abstract: This invention provides an excavator 1 for crushing a matter to be excavated, existing in an excavating hole in which a discharge liquid is fed, by electric discharge between a plurality of electrodes generated by high-voltage pulses. The excavator comprises a high-voltage pulse generator 2; a plurality of electrodes 17, 18, at least one of which is given a high voltage from the high-voltage pulse generator 2; discharge liquid circulating system 3, 4, 5a, 5b; and optimum condition setting devices 13, 14, 15, 16. Also, this invention provides an excavation method in which at least one of the parameters for excavation efficiency of i) load voltage required for crushing the matter to be excavated; ii) single pulse energy; and iii) quantity of discharge liquid, is optimized for minimization of power consumption required for excavation by using the excavator of this invention.

Abstract: A drilling apparatus includes a drill string, a drilling head located at a first end of the drill string, a drilling fluid pump located at a second end of the drill string, wherein the drilling fluid pump pumps a drilling fluid along the length of the drill string to the drilling head, and a traveling wave generator coupled to the drill string at a location downstream of the drilling fluid pump, wherein the traveling wave generator generates a series of ramped pressure pulses that are applied to the drilling fluid. The ramped pressure pulses are compressed by a reduction of the cross-sectional area of the drill string, and further by time compression caused by varying propagation rates of different portions of the pressure pulses pressure pulse if substantially formed at a surface of a drilling substrate. A shock wave associated with the compressed pressure pulse is generated substantially at the location of a surface of a drilling substrate.

Abstract: An electrohydraulic drilling system for drilling holes in material such as rock utilizing a drill stem connected to a flexible cable. The electrical spark or plasma that creates the electrohydraulic pressure wave is powered by an electrical pulse propagated down the cable from a pulse generator to the drill stem. An advance mechanism on a jackleg support is utilized to move the drill into the rock during the drilling process. The drill stem and cable combination enable holes to be drilled in the roof of tunnels where the floor to roof height is less than the depth of the hole to be drilled. The electrohydraulic process provides higher drilling efficiencies than conventional systems.

Abstract: A autonomous borehole data transmission apparatus for transmitting measurement data from measuring instruments at the downhole end of a drill string by generating pressure pulses utilizing a transducer longitudinally responsive to magnetic field pulses caused by electrical pulses corresponding to the measured downhole parameters.

Abstract: In a bore holes, a plurality of resilient members and plates are piled up alternately to form a laminate, and a deadweight is dropped onto the laminate. The resilient members are deformed due to the impact force of the dropped deadweight to cause bore hole water among the plates to be forced out in the outward direction, and elastic waves to occur in the bore hole wall.

Abstract: In a bore holes, a plurality of resilient members and plates are piled up alternately to form a laminate, and a deadweight is dropped onto the laminate. The resilient members are deformed due to the impact force of the dropped deadweight to cause bore hole water among the plates to be forced out in the outward direction, and elastic waves to occur in the bore hole wall.

Abstract: The seismic source (5) according to the invention is associated with a drill string (1) linking a drill bit to a surface installation close to the bit. It comprises a closed chamber (6) fastened inside a drill cellar (4) of the drill string. The section thereof is smaller than the inner section of the drill string, so as to allow free circulation of the drilling fluid. A reactive mass (8) may move within this chamber (6) and along the axis of drill string (1). Hydraulic or electro-mechanical means allow a strong alternating force of controlled frequency and duration to be applied to this mass. The energy necessary to the operating thereof is taken from the fluid current. This source requires no substantial modification in the usual drilling equipments. Drilling a well and performing seismic measurings may be achieved at the same time by means of the source by arranging sensors at the surface and/or in one or several adjacent wells.

Abstract: The method consists in performing seismic prospecting operations by using a drill bit (1) working at the bottom of a well (2), which generates very powerful acoustic jogs, in transmitting in real time or in delayed time reference signals representative of the jogs of the drill bit picked up in the immediate vicinity thereof by bottomhole sensors and in correlating the seismic signals picked up by a reception set with the reference signals coming from the bottom. The reference signals may be transmitted to the surface station through a line (4) included in a drill string (3). Absorbing elements are preferably interposed on the string to damp the vibrations propagating directly towards the surface along the drill string. Resonant elements and possibly acoustic discontinuity elements favouring resonances in the seismic frequency band may also be interposed.

Abstract: An acoustic wave generator for telemetering signals through a drillstem comprises a sub interposed in the drillstem with a central mandrel and a piston mass disposed in sleeved relationship around the mandrel and reciprocable by hydraulic pressure fluid to impose reaction forces on the mandrel and the drillstring at selected frequencies to transmit acoustic waves through the drillstring. A control system for operating the generator includes a hydraulic pump, a control valve and a frequency control circuit which operates the control valve to effect reciprocation of the piston mass at selected frequencies for transmitting serial data from the control system through the drillstring to a receiving system. The generator is coaxially arranged in the drillstring and is operable to generate high-energy acoustic wave signals for propagation through relatively long drillstrings.

Abstract: This disclosure is directed to a displacement amplifier for forming acoustic pulses and more particularly to one which incorporates a flexible movable lightweight diaphragm of rectangular configuration. It has upper and lower ends which are connected to opposing piston rods driven by duplicate pistons and double acting cylinders. The cylinders are located at opposite ends of the diaphragm or membrane. They are supported in an elongate tool which positions the flexible membrane in a generally rectangular window. This enables the membrane to flex as the pistons are driven, thereby enabling the flexure of the membrane to form dipole source for radially directed compression waves transmitted from the membrane in the window.

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 seismic acoustical signal source capable of selectively firing numerous, prewired explosive charges. The downhole seismic source uses a self-contained firing circuit that is capable of receiving select and fire signals from a seismic crew at the ground surface through a standard seven conductor wireline cable to detonate the explosive charges. The downhole seismic source is capable of generating numerous signals in a given downhole trip through the firing of many individual explosive charges.

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 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: 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: There is provided a new and useful tamping and topping plug for use in a seismic bore hole, and comprising a cylindrical body member having a forward and a rearward end and terminating at its forward end with a closed end part, a plurality of elongated members extending outwardly and rearwardly from at least one end and preferably from the forward and rearward ends of the body member, the members so arranged as to give the plug axial stability when inserted into a bore hole. There is also provided a process utilizing the plug for enhancing information available from seismic blasting.

Abstract: A system for directional drilling of boreholes into the earth under control of the driller at the surface, employing a rotating earth drill including a projectile firing mechanism, that is timed to nonsymmetrically fire projectiles into the earth at controlled angular positions that are offset from the axis of the drill and drill string in the desired direction of drilling.

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

Abstract: A method of measuring lithology, and other underground conditions, while drilling bores into the earth employing the repetitive firing of projectiles to fracture rock and penetrate the earth and detecting the high intensity acoustic signals being produced as the drill progressively penetrates.

Abstract: A method of and apparatus for determining the precise position of the drill bit on the bottom of a long drill string in a deep borehole in the earth, during a drilling operation. The method comprises placing a plurality of geophones in a three-dimensional array near the surface of the earth, above the expected position of the drill bit in the earth, causing at least a low energy seismic source to be initiated near the drill bit in the earth, repeating the source a number of times, and determining at the surface of the earth the times of initiation of each of the seismic waves. Responsive to the known times of initiation, stacking each of the repeated geophone signals from each of the geophones, for each of the repetitions of the source, whereby each of the stacked signals will be in-phase with those that resulted from earlier and later repetitions of the source. Several embodiments of an improved downhole seismic source are described, and an improved type of three-dimensional array.

Abstract: In generating seismic waves in earth a generator having a generally elongate, tubular expandable and contractible outer wall portion closed at its upper and lower ends by rigid strength members having separate input and return pressure lines is placed in a well bore, a hydraulic coupling pressure is applied through the input line which causes the expandable wall portion to engage and remain coupled with and in direct contact with the earth wall in the well bore and hydraulic pressure impulses are then cycled through the input and return lines at pressures greater than the coupling pressure to cause further expansion of the expandable wall portion, thereby generating and radiating seismic waves in the earth upon application of each impulse while maintaining the hydraulic coupling pressure sufficient to effectively maintain the outer wall anchored to the wall of the bore hole. The coupling pressure should be sufficient to anchor and couple the transducer to the well bore without any additional anchoring.

Abstract: A system for vibrating the earth in a location where seismic mapping is to take place, including forming a relatively shallow hole in the earth such as a hole 10 feet deep, placing a solid propellant in the hole, sealing a portion of the hole above the solid propellant with a device that can rapidly open and close to allow a repeatedly interrupted escape of gas, and igniting the propellant so that high pressure gas is created which escapes in pulses to vibrate the earth.

Abstract: Method and apparatus are provided for generating in situ in a zone of earth surrounding a bore hole both longitudinal and shear waves and of predetermined relative amplitude, entirely mechanically, avoiding use of explosives, and with relatively low power requirements for the stress waves generated. Subterranean impacts generating high amplitude stress waves equivalent to those generated by fifteen pounds of TNT or multiples of such quantities of TNT are realized. These high amplitude waves are produced in an annular zone ten feet or more from the earth bore, where the earth specimen has not been previously disturbed and its measured properties are therefore truly representative of the medium.