Abstract: The invention provides methods and apparatus for detecting seismic waves propagating through a subterranean formation surrounding a borehole. In a first embodiment, a sensor module uses the rotation of bogey wheels to extend and retract a sensor package for selective contact and magnetic coupling to casing lining the borehole. In a second embodiment, a sensor module is magnetically coupled to the casing wall during its travel and dragged therealong while maintaining contact therewith. In a third embodiment, a sensor module is interfaced with the borehole environment to detect seismic waves using coupling through liquid in the borehole. Two or more of the above embodiments may be combined within a single sensor array to provide a resulting seismic survey combining the optimum of the outputs of each embodiment into a single data set.

Abstract: A seismic sensor, has a case, a pre-charged, non-conductive membrane located between two plates that form a capacitor and accommodated inside the case, with one of the plates being immovable relative to the case and the other of the plates being movable relative to the one plate under the action of seismic activity of a medium in which the sensor is located, so that the capacitor produces an electrical signal responsive to the seismic activity, and a mass increasing element associated with the movable plate so as to increase mass of the movable plate and therefore enhance oscillations of the movable plate under the action of the seismic activity.

Abstract: A seismic sensor, comprising a case, a pre-charged, non-conductive membrane located between two plates that form a capacitor and accommodated inside the case, with one of the plates being immovable relative to the case and the other of the plates being movable relative to the one plate under the action of seismic activity so that the capacitor produces an electrical signal responsive to the seismic activity of a medium in which the sensor is located, and a mass increasing element associated with the movable plate so as to increase mass of the movable plate and therefore to enhance oscillations of the movable plate under the action of the seismic activity, the mass increasing element being formed as a further case which is connected to the movable plate and is located in condition of equilibrium in an inoperative position of the sensor.

Abstract: The logging tool of this invention includes a transmitter conveyed on a drilling collar for exciting a quadrupole signal in a borehole being drilled by a drill bit and a receiver for receiving the signal. The transmitter is operated at a frequency below the cut-off frequency of the quadrupole collar mode. The received signal consists primarily of the formation quadrupole mode which, at low frequencies, has a velocity that approaches the formation shear velocity. The transmitter, in one embodiment, consists of eight equal sectors of a piezoelectric cylinder mounted on the rim of the drilling collar. The value of the cut-off frequency is primarily dependent on the thickness of the drilling collar. Alternatively, the transmitter may be operated to produce both the collar mode and the formation mode and a processor may be used to filter out the collar mode.

Abstract: A method for processing magnetotelluric signals to identify subterranean deposits is provided for. The methods comprise obtaining magnetotelluric data from an area of interest. The magnetotelluric data comprises the amplitude of magnetotelluric signals recorded over time at one or more defined locations in the area of interest. The data for each location then is filtered through a set of frequency filters. The frequency filters correspond to subterranean depths over a range of interest. Amplitude peaks in the filtered data then are identified and analyzed to determine a value correlated to the resistance of the earth at each frequency and location. The resistance values are indicative of the presence or absence of deposits at the corresponding subterranean depth.

Abstract: A method and device for seismic exploration of a subsea geologic formation by pickups set on the sea bottom and intermittently connectable to active data acquisition stations (11) brought nearby. Permanent passive reception stations (1) comprising a heavy pedestal provided with housings for seismic pickups (geophones (6), hydrophone (7) which receive acoustic or seismic signals from the underlying formation are arranged at the bottom of the water body. When collection sessions for the signals received by the pickups are scheduled, mobile active acquisition stations (11) connected to permanent passive reception stations (1) are positioned at the bottom of the water body. The signals picked up are then recorded, for the time required to carry out at least one session of acquisition and recording of the acoustic or seismic signals received by the passive stations in response to the emission of seismic waves by one or more seismic sources.

Abstract: Array quadrupole data obtained in a LWD environment are processed to determine the shear velocity of an earth formation taking into account dispersion effects caused by the logging tool. When this processing is done in an azimuthally anisotropic formation, the shear velocity that is obtained is the slow shear velocity. When 4C (cross-dipole) data are also obtained, then both the fast and slow shear velocities of an azimuthally anisotropic formation can be obtained.

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 plurality of heavy mass irregularities attached to an inner wall of the drill collar attenuate waves traveling through the collar. The plurality of heavy mass irregularities are spaced and sized for the maximum attenuation of acoustic pulses in a predetermined frequency range. The mass irregularities may be rings firmly coupled to the outer surface of the collar. Alternatively, the mass irregularities may be rings firmly coupled to the outer collar surface by neck pieces, extending inwardly from the inner circumference of the ring. The mass irregularities may be made of steel or tungsten. In another preferred embodiment, the mass irregularities are asymmetrically coupled to an outer collar wall for providing preferential directional attenuation.

Abstract: An acoustic logging apparatus comprises a drill collar conveyed on a drilling tubular in a borehole within a formation. At least one transmitter is disposed in the drill collar. The transmitter includes at least one magnetostrictive actuator cooperatively coupled by a flexure ring to a piston for converting a magnetostrictive actuator displacement into a related piston displacement for transmitting an acoustic signal in the formation.

Abstract: An acoustic logging tool including an elongated body, one or more acoustic transmitters, one or more acoustic receivers, and a broadband acoustic absorption region. A substantial portion of the broadband acoustic absorption region is between the transmitter and the receiver. The acoustic energy absorber includes a first absorber for absorbing a first mode of acoustic energy and a second absorber for absorbing a second mode of acoustic energy. The acoustic absorption material used to make the acoustic absorbers has an acoustic impedance between 20% and 120% of the material used to construct the acoustic logging tool. The acoustic logging tool includes an elongated hollow tool body, an insert configured to be inserted into the tool body, and a ring configured to be inserted onto the insert. A first element is supported by the ring and exposed to a pressure field, and a second element is supported by the ring and exposed to a pressure field.

Abstract: The logging tool of this invention includes a transmitter conveyed on a drilling collar for exciting a quadrupole signal in a borehole being drilled by a drill bit and a receiver for receiving the signal. The transmitter is operated at a frequency below the cut-off frequency of the quadrupole collar mode. The received signal consists primarily of the formation quadrupole mode which, at low frequencies, has a velocity that approaches the formation shear velocity. The transmitter, in one embodiment, consists of eight equal sectors of a piezoelectric cylinder mounted on the rim of the drilling collar. The value of the cut-off frequency is primarily dependent on the thickness of the drilling collar. Alternatively, the transmitter may be operated to produce both the collar mode and the formation mode and a processor may be used to filter out the collar mode.

Abstract: The acoustic isolator assembly of the present invention comprises a elongated cylindrical body suited for connection to an acoustic array and subsequent disposition within a wellbore. According to one embodiment of the present invention, the acoustic isolator comprises a plurality of cylindrical isolator modules that are coaxially arranged to form the body of the tool. Each isolator module comprises a spring disposed within an outer housing. The separate isolator modules are attached to one another by connecting rods around which are disposed a plurality of metal spacers. The isolator module further comprises mechanical stops that limit the deflection of the spring during high axial loading. These features enable the acoustic isolator assembly to withstand the high loading that may be applied during logging operations. Therefore, the isolator modules are capable of supporting high compressive and tensile loads without suffering permanent deformation of the springs.

Abstract: The invention provides an instrument suitable for measuring seismic waves in an environment which comprises a wave guide through which a seismic wave may propagate substantially without dispersion wherein the wave guide is provided with means for measuring its deformation.

Abstract: A method and apparatus for isolating a seismic sensor module from high-g shock loads such as those encountered during handling, deployment and retrieval of the module. The sensor module includes one or more MEMS accelerometers in an electronics package. The electronics package is housed within a module case. And one or more isolators are disposed between the electronics package and the module case to provide shock isolation.

Abstract: A module is described for acquiring geophysical signals. The module includes at least one casing which is individually linked to one track. Each casing houses a processor which operates to digitize the geophysical signals. The module further includes two cable sections associated with each casing. Each cable section includes at a first end, a connector suitable for being coupled up to a complementary connector, and at a second end, an adapted configured to be fixed to a casing and to effect an electrical link with the processor housed in the casing.

Abstract: A sleeve for an acoustic logging tool has a structure with a window section having fewer bars than a conventional sleeve separated by a slotted region with thin circumferential slots which are stress-relieved at the ends (“dumb-bell” shaped). Steel receiver mounts are provided for hydrophone pressure sensors and this, together with the axially oriented hydrophones makes the tool less susceptible to interfering vibration.

Abstract: A wellbore seismic receiver system is disclosed which includes a system housing adapted to traverse a wellbore and a sensor housing adapted to be placed in contact with a wall of the wellbore. The sensor housing has at least one seismic sensor disposed therein. A compliant chamber couples the sensor housing to the system housing, and a controllable source of pressurized gas is coupled to an interior of the chamber. The gas source is adapted to selectively pressurize the chamber to place the sensor housing in contact with the wall of the wellbore.

Abstract: A seismic data acquisition technique comprises laying a seismic data cable having a plurality of spaced apart connection nodes and a plurality of sensor strings connected to the connection nodes along a line of the area to be seismically surveyed. Each sensor string comprises ten or more seismic sensors for producing respective output signals representative of a seismic signal received by them. The sensors of the sensor strings are laid out in at least two sets of groups, each group containing several of the sensors and transmitting at least one seismic signal to a connection node, and the sets of groups being disposed along respective spaced apart lines generally parallel to the line along which the seismic data cable is laid.

Abstract: A method for seismic exploration using nonlinear conversions between electromagnetic and seismic energy, with particular attention to the electromagnetic source waveform used. According to the invention, seismic returns from a source waveform are correlated with a reference waveform, with both waveforms custom designed to minimize both correlation side lobes and interference from linear electroseismic effects. A waveform element is selected which may be sequenced by a binary or similar digital code embodying the desired custom design to generate an input sweep with the needed depth penetration and noise suppression. Correlation of the seismic response with the reference waveform in a data processing step mathematically aggregates the seismic response from the input sweep into a single wavelet. Preferred binary digital codes include prescribed variations of maximal length shift-register sequences. Also, an apparatus for generating the desired waveforms.

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: The present invention discloses a shaftless acoustic source 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 means may be used to retract the bullet back into the solenoid after firing.

Abstract: This invention relates to mapping the hydrocarbon reservoir characteristics by mapping the reservoir formations that display dynamic elastic nonlinearity responses to the seismic signals. The main reason of this nonlinear behavior in the reservoir rocks is their bulk rock property: the porosity, fractures, differential pressure and pore saturation. To map these bulk rock properties, the interaction of the two seismic waves as they propagate through elastically nonlinear rocks is recorded. Two compressional seismic signals are transmitted from the surface. Seismic reflection data using surface or borehole detectors are recorded. One of the transmitted signals is a conventional swept frequency and the other is a mono-frequency signal. During the propagation of these two signals through the elastically nonlinear reservoir rocks, there is an interaction between the two signals. The sum and difference frequencies of the two primary seismic signals that were transmitted from the surface are created.

Abstract: A borehole logging tool system includes a surface system, a logging array, and a logging cable providing power supply and data paths connecting the logging array to the surface system, wherein the logging array includes a series of discrete sondes connected together. The sondes in the logging array, for example a borehole seismic logging array, are connected to their neighbours by means of lengths of logging cable. Such cable can be the same as that connecting the logging array to the surface system. The logging array can also include a master controller module which communicates with the surface system and which includes a first controller module which connects to the surface system and a second controller which controls operation of the sondes in the logging array independently of any other borehole logging tools connected to the surface system.

Abstract: For determination of the laminar structure and other characteristics of a ground, oscillation sensors for detecting the vertical component or vertical and horizontal components of oscillations are disposed at three or more points within a comparatively small area at ground level to simultaneously measure microseisms at the respective points, if necessary with locations of said points being varied and measurements be performed at the respective locations and the vertical oscillation data or vertical and horizontal oscillation data thus generated are analyzed. This method not only permits an expedient, positive and accurate assessment of the laminar structure and other characteristics of the ground but also permits the measurement of ground structure even when the area available for measurement is small.

Abstract: The present invention provides a new and unique method, sensor, and apparatus for performing a seismic survey of an earth formation in relation to a borehole. The method includes arranging at least one strain seismic sensor in conjunction with a borehole structure, and mechanically coupling the borehole structure to the borehole to allow seismic data to be accurately transferred to the sensor. The sensor is preferably a fiber optic sensor, including a Fiber Bragg Grating which may be coupled to a relevant borehole structure in a number of ways.

Abstract: A borehole tool including a tool body having and an anchoring mechanism, the anchoring mechanism having a drive mechanism including a motor, drive shaft, and clutch; an anchor arm moveable between first and second positions relative to the tool body; a push rod connecting the anchor arm to the drive mechanism; and a spring acting to bias the arm into a first position relative to the tool body. The push rod extends through the clutch mechanism and is engaged by the spring to bias the arm into the first position, and is also driven by the drive mechanism through the clutch to move the arm between the first and second position. The push rod may be connected to the anchor arm by a link. Measurement devices may be used to determine the position of the anchor arm or the tool body.

Abstract: A non-contact vibrometer is employed to measure seismic energy imparted to the earth by a land vibrator. The non-contact vibrometer can be a laser vibrometer operable to measure the motion of a baseplate of the land vibrator. A computing device can be used to record both the imparted seismic energy detected by the non-contact vibrometer and reflected seismic energy sensed with geophones.

Abstract: A system and method for utilizing a surface located oscillator to generate seismic signals at a downhole location. The system includes a vibratory source for generating axial vibrational energy in a tubular string anchored in the borehole at a suitable location. The vibratory source may be operated at a predetermined frequency or may generate a swept frequency signal. The axial vibrations are transmitted through the tubular string and impart a seismic signal through the anchor to the formation.. In different configurations, the system imparts broadband seismic signals into the formation. Sensors are mounted on the vibratory source and downhole anchor for monitoring the system operation. Seismic receivers are deployed on the surface, in offset wells, or in the source well. Signals from the receivers are transmitted to a control unit. The control unit utilizes the sensor and receiver signals to control the operation of the vibratory source.

Abstract: An acoustic receiver for sensing acoustic waves and generating orthogonal triaxial acoustic response data representative of said acoustic waves is disclosed. The receiver has at least four acoustic sensors oriented in at least four different directions. Each of the acoustic sensors is adapted to produce an electrical signal in response to an acoustic wave impinging thereon. The inventive acoustic receiver also includes means for combining the electrical signals to yield orthogonal triaxial acoustic response data. In one embodiment the means for combining the electrical signals comprises wiring the acoustic sensors in two series pairs to produce a combined output along two of the three orthogonal axes and orienting at least one acoustic sensor substantially parallel to the longitudinal axis of the acoustic receiver.

Abstract: A method and system for determining the location of a microseismic event is disclosed. An electromagnetic sensor measures the electromagnetic energy which is caused by a microseismic event. Seismic data from the microseismic event is measured and recorded using plurality of ground motion sensors. The time at which microseismic event occurred is estimated based at least in part on the time at which electromagnetic energy caused by the microseismic event is received by the electromagnetic sensor. The location of said source of the microseismic event is determined using the estimated occurrence time and the time at which the seismic energy arrived at the ground motion sensors. A method of triggering a seismic recording device is also disclosed. The electromagnetic energy from a microseismic event is measured and recorded using an electromagnetic sensor. The time at which the microseismic event occurred is estimated based on the measured electromagnetic energy.

Abstract: An apparatus (10) may implement a method (160) for creating (162) a data-domain sampled network (206). In certain embodiments, a method in accordance with the invention may define (166) a data domain, provide (172) points in a data-domain space or sub-space, followed by analyzing (174) data in the data domain (100). Analysis (174) may involve selecting (175) the dimensions or variables of interest, evaluating (176) or determining (176) the cycles per dynamic range, selecting (177) an interpolation method, and selecting (178) a number of sample points (223) in each respective dimension (227, 228). Providing (180) a data-domain network (206) typically includes applying (184) sampling theory to a native data domain (100). Calculating (188) waits for this by an interpolation module (212) specifies the data-domain network in its native domain (100).

Abstract: A device which picks up elastic waves, such as a geophone for example, in positions far from the natural operating position for which it is designed. The device comprises an electrodynamic pickup including a magnet (1), a moving coil (2) placed in the magnetic field, springs (4) suited to hold the coil in a well-centered static position when the axis thereof is parallel to a selected reference direction (horizontal or vertical, for example) and a current source which applies to the coil an electrical current which corrects any unbalance of the coil in relation to the static position thereof due to an inclination of the axis of the coil in relation to the reference direction. The current source may be for example a source of direct current (5) and a voltage divider (P) whose division factor depends on the angle between the axis of the pickup and a reference axis or a compensating device suited to minimize the distortion ratio of the geophone.

Abstract: An acoustic vector sensor for monitoring acoustic energy underwater includes an acoustic sensing tri-axial accelerometer, a body of syntactic foam encasing the accelerometer, a body of viscoelastic rubber encasing the body of syntactic foam, and a rigid plastics coating encasing the body of viscoelastic rubber.

Abstract: An interferometric geophone includes a freely-falling reference mass and an interferometric arrangement to measure motion of a surface to which the geophone is attached. The mass may fall through an evacuated chamber. A carriage arrangement may reposition the reference mass for another fall. The reference mass has top and bottom retro-reflectors. The interferometric arrangement includes a laser and a beam-splitter that divides the laser beam into two beams directed toward the top and bottom of the reference mass by partially reflecting surfaces on prisms or mirrors. When the beam encounters the first face of each prism or a first mirror it is split again. One of the split beams is directed toward the falling retro-reflector; the other beam passes through the prism or mirror and encounters the second face. The retro-reflector returns the first split-beam to the second face via a lens arrangement.

Abstract: A borehole tool, such as a seismic shuttle-type logging tool, including a tool body having at least one sensor package and an anchoring mechanism, the anchoring mechanism having a drive mechanism including a motor, a drive shaft and a clutch; an anchoring arm moveable between first (extended)and second (retracted) positions relative to the tool body; a push rod connecting the anchoring arm to the drive mechanism; and a spring acting to bias the arm into a first position relative to the tool body. The push rod extends through the clutch mechanism and is engaged by the spring to bias the arm into the first position, and is also driven by the drive mechanism through the clutch to move the arm between the first and second positions. The spring is a coil spring surrounding the drive mechanism and acting on the push rod directly.

Abstract: An apparatus and a method for anchoring a seismic geophone to soil. The apparatus comprises a base having a base section for engagement with the geophone. The base also has an anchor end attachable to the soil to restrict movement of the geophone after said base section is engaged with the geophone and after said anchor end is attached to the soil. A latch can detachably secure the base section to the geophone or to a seismic cable attached to the geophone, and the base can comprise a biodegradable material. The method of the invention attaches the base anchor end to the soil so that the base section engages the geophone to restrict movement of the geophone from the desired location relative to the soil.

Abstract: For determination of the laminar structure and other characteristics of a ground, oscillation sensors for detecting the vertical component or vertical and horizontal components of oscillations are disposed at three or more points within a comparatively small area at ground level to simultaneously measure microseisms at the respective points, if necessary with locations of said points being varied and measurements be performed at the respective locations and the vertical oscillation data or vertical and horizontal oscillation data thus generated are analyzed. This method not only permits an expedient, positive and accurate assessment of the laminar structure and other characteristics of the ground but also permits the measurement of ground structure even when the area available for measurement is small.

Abstract: The present invention provides a method for forming wellbores. In one method, one or more wellbores are drilled along preplanned paths based in part upon seismic surveys performed from the surface. An acoustic transmitter conveyed in such wellbores transmits acoustic signals at a one or more frequencies within a range of frequencies at a plurality of spaced locations. A plurality of substantially serially spaced receivers in the wellbores and/or at s receive signals reflected by the subsurface formations. The sensors may be permanently installed in the boreholes and could be fiber optic devices. The receiver signals are processed by conventional geophysical processing methods to obtain information about the subsurface formations. This information is utilized to update any prior seismographs to obtain higher resolution seismographs. The improved seismographs are then used to determine the profiles of the production wellbores to be drilled.

Abstract: Acoustic intensity is measured by a submerged probe consisting of two passive geophones mounted in spaced relationship with their sensing axes aligned. The geophones are connected through a cable to a remote spectrum analyzer in which acoustic intensity is computed from the velocity gradient between the two geophones. The exclusive use of geophones, which inherently have low impedance outputs, eliminates the need for preamplification in the probe. The geophones are mounted inside an acoustically transparent, thin rubber shell, which reduces the effects of noise due to flow.

Abstract: A well tool in accordance with the invention comprises an attenuation device which attenuates tube waves associated with an elastic wave emission and/or reception set (1, 12). The attenuation device comprises a bubble generator (2) which releases into the well a gas not readily soluble in the well fluid, slightly overpressured in relation to the hydrostatic pressure, in the form of calibrated bubbles which greatly attenuate the parasitic tube waves. The attenuation device is placed above or below the elastic wave emission and/or reception set having a plurality of pickups whose signals are acquired by a local electronic module (14) and/or a source of elastic waves such as a vibrator. A bubble trap (17) is preferably associated with the bubble generator (2) in order to limit the volume of gas to be generated in situ. The invention is applicable to VSP type seismic prospecting and acoustic logging.

Abstract: An interpenetration apparatus for the measurement of a magnitude of a blasting vibration comprises a housing including a fixture and a mover divided into two, symmetrically, in a longitudinal direction, in which the fixture includes a space for receiving a cable and the mover includes at least two grooves perforated to receive sensors, respectively; a head portion for fixing the front end of coupled fixture and mover to prevent the escape of the mover from the fixture; a handle including a fixing rod threadedly coupled to the rear portion of the fixture; a connecting rod connected to the fixing rod and extended in a predetermined length therefrom to insert the interpenetration apparatus into a working hole perforated adjacent to an approach to a tunnel; and a traction tool connected to the rear end of the mover to operate the mover, thereby enabling the housing to be at the nearest position from the blasting place, and sensitively detecting the wave motion of the blasting vibration as well as three dimensiona

Abstract: An apparatus and method for selectively locking the orientation of seismic data sensor capable of detecting data regarding a seismic event. A gimbal orients the sensor into a selected vertical orientation, and a switch operates a clutch to lock the sensor from further movement. A controller can identify a time interval correlating with a seismic event, and the controller operates the switch to lock the sensor before the seismic event begins. After the completion of the seismic event, the switch unlocks the sensor so that the gimbal can permit reorientation of the sensor. The locking mechanism eliminates noise associated with moving gimbal components and is suitable for land based and marine seismic operations.

Abstract: A seismic acquisition system and method utilizing an array of buried geophones storage devices or containers (16) each having a geophone (40) which may be permanently stored in container (16) in a fluid tight relation. The storage container (16) includes a base (26), a tubular cylindrical body (28), and an upper cap (32) threaded onto body (28). The storage container (16) is shown in FIG. 2 in an operable relation and in FIG. 3 with geophone (40), lead (52), and connector (54) in a stored relation. In the event an additional survey or shoot is conducted at a later time, such as a one year time interval, the buried storage containers (16) are utilized upon removal of outer caps (32) and withdrawing of geophone connectors (54) for connection in a mating relation to cable connectors (20).

Abstract: A method for monitoring production mineral reservoirs, the method comprising: permanently installing a geophone in a borehole; generating a first set of seismic waves; receiving a first set of seismic data with the geophone; recording the first set of data of said receiving a first set of seismic data; generating a second set of seismic waves after sufficient time has passed for conditions in the reservoir to have changed from the generating a first set of seismic waves; receiving a second set of seismic data with the geophone; and recording the second set of seismic data of said receiving a second set of seismic data. A method for installing instruments below the surface of the earth, the method comprising: drilling a borehole with a drill apparatus; inserting an instrument in the borehole; and permanently fixing the instrument in the borehole.

Abstract: A hydrophone arrangement, housed within a dome shaped concrete and steel bunker, to accurately establish a bearing of a target object while diminishing potential displacement of the hydrophone arrangement from an initial installed position. A plurality of hydrophones are centrally positioned within the bunker and equally spaced about a periphery of a steel cylindrical member so that each hydrophone receives acoustic energy in a time delay manner with respect to the other adjacent hydrophones so that a bearing determination may be made from information received by a single stand alone bunker. An acoustic horn may also be provided to focus the acoustic energy towards the hydrophones to improve the signal-to-noise ratios and provide control of the phase of the acoustic energy as the energy is received by the hydrophones.

Abstract: A repairable geophone housing having a fully molded waterproof one piece upper body which is seabably and releasably connectible to a lower body. All surfaces within the upper body are bonded to prevent moisture entering and the geophone transducer may be replaced if desired.

Abstract: The invention relates to a device for exploring an underground formation crossed by a well, suited to work in well portions where the advance thereof under the effect of gravity is difficult, notably in horizontal well portions or in well portions greatly inclined to the vertical. A plurality of rigid exploration modules (Mi) are interconnected end to end, each one including a rigid pipe (1), a flexible leaf (11) fastened to each pipe (1) so as to press against the wall of the well at least one box (18) containing sensitive elements, a linking cable (32) connected to a surface central station (40), and a connecting block (26) comprising an acquisition system (37) connected to the various modules (M1-Mn) by a bundle of electric conductors running through the tubular elements (1), and a deferred electric connection useful in damp conditions between linking cable (32) and the acquisition system.

Abstract: A cart-mounted acoustic transmitter and receiver system for echo-locating underground structures, such as piping. A transmitting transducer, mounted in a non-resonant tube and positioned adjacent to the ground, directs sound waves downwardly through an air column while a receiving transducer, rolling over the ground, picks up echoes returned from buried objects. The rolling transducer includes a piezo-electric transducer mounted in a tubular plastic axle on which an elastomeric disc rotates making contact with the ground. A pair of port and starboard rolling transducers provide inputs to a differential amplifier to enhance detection by increasing discrimination against the return from the benign land mass.

Abstract: An improved marsh case is disclosed. The marsh case contains and protects a geophone, which is inserted into the earth in the course of oil exploration. The marsh case provides an cap having an upper opening through which wires pass to the geophone and a lower internally threaded opening that attaches to the body of the case. The body of the case provides an upper externally threaded opening which attaches to the cap, and a lower internally threaded conical surface which allows a threaded cylindrical surface of a spike to be attached. The threads of the body are slightly tapered, thereby relieving some of the stress that would otherwise be applied to the threads. The rim of the upper external threaded opening of the body and an internal annular shoulder in the cap compress an O-ring, thereby making a water-tight seal.