Abstract: The device for automatic management of an actuator controlled by a servo-valve, includes a sensor for measuring the actual value of a parameter at the output of the actuator for a given control command, a computation unit for computing a theoretical value of said parameter, by applying the control command to a nominal performance model which models the operation of the actuator exhibiting nominal performance, a computation unit for computing the difference between the measured actual value of the parameter and the computed theoretical value of said parameter, a control unit for computing an adapted gain as a function of this difference, and a link for applying the adapted gain to the servo-valve for it to use it as gain value, so as to allow the actuator to restore nominal performance.

Abstract: There is taught herein a system and method for creating an improved seismic source signal by applying a feedback mechanism, active adaptive control, to perturb a resonator device configuration on the fly so as to ensure that the overall trajectory of the sweep is correctly produced, even though the precise details of each oscillation of the source are still not constrained. An embodiment teaches a method for adjusting the squeeze piston or tow depth of a resonant piston seismic source to bring the resonant frequency to a desired value. As a consequence, the resulting seismic signal is improved as compared with seismic signals acquired via resonators that do not utilize the instant teachings.

Abstract: Methods and apparatus for using multi-component geophones and/or multi-component geophone arrays to measure flow-induced acoustic energy produced in wellbores are provided. With the use of the multi-component geophones, the measured acoustic energy may be resolved into its directional components. The computed directional energy components may be mathematically compared to numerically highlight ambient flow conditions (e.g., leaks in casing or other conduit, points of fluid entry/exit/restrictions between the casing and the formation). The use of an array of multi-component geophones allows for the use of geophone move-out curves to further identify acoustic energy source locations.

Abstract: An apparatus and system for acquiring seismic data over a loose surface is disclosed. The apparatus includes a housing capable of moving on the loose surface with an opening configured at a bottom surface of the housing. The apparatus further includes a seismic sensing unit configured within the housing at an angle with respect to a horizontal plane. The horizontal plane may be the bottom surface of the housing. The seismic sensing unit is operable to retractably move within the housing towards and away from the opening. In response to the seismic sensing unit moving towards the opening, the seismic sensing unit establishes contact with the loose surface for acquiring the seismic data.

Abstract: A seismic vibrator includes a baseplate having a surface configured to couple to a ground surface. A driver is coupled to the baseplate and is configured to move the baseplate in a vibratory manner. A decoupling system is coupled to a part of the baseplate other than the ground-contacting surface. The decoupling system includes a first layer having a Young's modulus greater than that of a second layer coupled to the first layer. The second layer is coupled to the baseplate. The Young's moduli, thicknesses and masses of the first and second layer are selected to provide the decoupling system with a resonant frequency of at most, a spatial aliasing frequency of seismic sensors deployed on the ground surface or a lowest seismic frequency of interest.

Abstract: A vibration sensor system for contacting the surface of a solid medium for detecting horizontally polarized shear waves and compressional waves. At least two contact points interface between a vibration sensor array and the solid medium to provide uninterrupted contact with the medium during detection of dynamic motions in the medium. A single vibration sensor is mounted on at least two adjacent contact points to convert detected dynamic motions to corresponding electrical signals. The single vibration sensor mounted on the two adjacent contact points forms a sub-array. The vibration sensor system has at least two sub-arrays. A conditioning and combining member treats sensor electrical signals from at least two sub-arrays to form a composite output signal for the system.

Abstract: An apparatus and method for transporting a payload over a surface is provided. A vehicle supports a payload with a support partially enclosed by an enclosure. Two laterally disposed ground-contacting elements are coupled to at least one of the enclosure or support. A motorized drive is coupled to the ground-contacting elements. A controller coupled to the drive governs the operation of the drive at least in response to the position of the center of gravity of the vehicle to dynamically control balancing of the vehicle.

Abstract: The current invention minimizes the energy losses by pointing the geophone's internal system, which consists of a magnet bar, coil, and springs, towards signals reflected from targets.

Abstract: A method and apparatus suitable for coupling seismic or other downhole sensors to a borehole wall in high temperature and pressure environments. In one embodiment, one or more metal bellows mounted to a sensor module are inflated to clamp the sensor module within the borehole and couple an associated seismic sensor to a borehole wall. Once the sensing operation is complete, the bellows are deflated and the sensor module is unclamped by deflation of the metal bellows. In a further embodiment, a magnetic drive pump in a pump module is used to supply fluid pressure for inflating the metal bellows using borehole fluid or fluid from a reservoir. The pump includes a magnetic drive motor configured with a rotor assembly to be exposed to borehole fluid pressure including a rotatable armature for driving an impeller and an associated coil under control of electronics isolated from borehole pressure.

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 seismic shear wave generator comprising a seismic wave source (3) arranged on a base plate (11) arranged for being placed at the seabed, and a coupling device (1) arranged for coupling the wave source (3) mechanically to the seabed in order for shear waves to be transmitted to the seabed. The novelty of the invention is as follows: a cylindrical skirt (1) closely arranged along the base plate's (11) circumference and extending down from the underside of the base plate (11), and open downwards, and a pump device (2) arranged for pumping water respectably out of, and into, the skirt (1) and form vacuum or overpressure, respectively, in a closed cavity formed by the skirt (1) and the base plate (11) and the seabed (1) is lowered onto the seabed. By means of the device mentioned above the shear wave generator may be suctioned fixed to the sea bed and thus transfer shear waves via the skirt (1) to the seabed.

Abstract: Seismic wave reception device comprising a hydrophone and/or a geophone and method for coupling it (or them) with a solid medium such as the subsoil. The device comprises at least one hydrophone (2) immersed in a closed flexible-walled sheath (7) filled with liquid (8) that is closed at one end by a sealed plug (9) provided with a sealed duct for a cable (10) connecting the hydrophone to a signal acquisition means (E). The sheath is arranged in a cavity (6) and tightly coupled with medium (5) substantially over the total surface thereof, preferably by means of a hardenable material such as cement. A geophone can be placed in the same coupling material in the vicinity of sheath (7) containing hydrophone (2). Application: seismic prospecting or monitoring operations in an underground formation, notably in order to discriminate the seismic upgoing and downgoing waves.

Abstract: An apparatus for detecting an underground abject includes a container in contact with the ground surface; a medium disposed in the container; at least one acoustic sensor disposed in the medium in the container; and an output device connected to the acoustic sensor. A portion of the container in contact with the ground is substantially acoustically transparent and conforms to contours of the ground. The acoustic impedance of the medium in the container is substantially the same as the acoustic impedance of the ground. A method of detecting an underground object includes receiveing reflected acoustic noise with at least one acoustic sensor immersed in a medium, the mediukm being desposed in a container in contact with a ground surface; converting the reflected acoustic noise to electrical signals; and, using an output device, converting teh eletrical signals to a form that can be sensed by a human to determine if the undergroung object has been detected.

Abstract: A method for the study of elastic wave phenomena in the ground, where the detection of said phenomena is carried out with the use of at least a geophone comprising at least a couple of transducers (20, 21; 37, 38), each transducer (20, 21; 37, 38) being apt to detect horizontally polarized shear waves, represented by SH signals, and compression waves, represented by P signals.

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: A method for echo-locating underground structures, such as piping, by launching a series of acoustic impulses into the ground to insonify the structures in an area where the structures are believed to be buried, detecting acoustic echoes returned from the insonified structures and displaying the returned echo data in such a manner that the oldest sequence of echo signals appears in an upper portion and the newest in a lower portion of the display.

Abstract: To increase a yield of a hydrocarbon such as oil from a subsurface reserv, the reservoir is stimulated by pumping liquid gun propellant (LP) into the reservoir and igniting the LP. The LP is pumped into a packed-off region in a cased well; the depth of the packed-off region is selected to lie within the reservoir. The ignition of the LP causes a pressurization of the reservoir, thus fracturing the reservoir. The fracture increases a surface area through which the hydrocarbon can be extracted, and the heat from the ignition reduces the viscosity of the hydrocarbon.

Abstract: A seismic vibrator system for imparting compressional and shear wave vibrations into the earth has an earth contacting base with a vertical post. A tubular hub is slidably received on the post in a piston/cylinder relationship. Spaced apart horizontal top and bottom plates are secured to the hub. A mass is slidably supported between the plates. Pistons interconnect the hub and the mass. Hydraulic energy is used to reciprocate the mass vertically on the post and horizontally between the plates.

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: Method and apparatus for carrying out seismic survey includes a plurality of spaced apart seismic detecting sensors each having a geophone unit for detecting seismic activities. The sensors are linked serially with a cable. One end of each geophone unit is flexibly linked to a carrier frame so that the geophone units pivotally move freely relative to the carrier frames. The cable passes through the carrier frames so that the carrier frames are spaced apart serially. Each geophone unit carries a vibrator, a plurality of geophones, a compass, and an inclinometer. The vibrator is positioned on the free end portion of the geophone unit, for embedding the geophone into the ground, while the compass is positioned farthest away from the vibrator. The free pivotal movement of the geophone units enables them to dig into the ground.

Abstract: Within the scope of operations of long-term regular monitoring of an underground area, a seismic emission-reception device is installed in a fixed position on the production site, so as to have time stable operating conditions of identical emission-reception locations, identical quality of coupling with the formations, etc. The device includes a plurality of seismic sources (S1 . . . Sn) in fixed places at the surface or buried beneath the surface, on either side of a production well (1), and at least one array of receivers (R) set in a fixed position at the surface or in at least one well. Explosive sources, hydraulic overpressure sources, electromechanical sources, etc, can be used and connected to a plant (3) providing energy using an explosive gaseous mixture, which may be a constituent taken from the monitored area, fluid under pressure transmitting hydraulic shocks or vibrations, etc, by means of buried pipes or cables (2).

Abstract: A receiver consistent deconvolution operator models the damped oscillatory wavetrain that is related to geophone coupling to the water bottom. The operator is a best-fitting function that endeavors to describe the difference in coupling response between a well-coupled in-line geophone relative to an imperfectly-coupled cross-line geophone. The operator is applied to the cross-line signals to compensate the signals for the distortion due to imperfect cross-line ground coupling.

Abstract: An apparatus and method for generating a seismic signal in the earth consisting of positioning a force-modulating means on the surface of the earth and then positioning a vehicle such that at least some of the weight of the vehicle is supported by the force-modulating means. At least one of the vehicle drive wheels is then rotated to cause the force applied to the earth by the force-modulating means to change thereby generating a seismic signal in the earth.

Abstract: An inference device for discriminating an earthquake includes an ON/OFF signal generating means for generating an ON/OFF signal corresponding to an oscillatory wave, a characteristic parameter extracting means for extracting at least one of three characteristic parameters consisting of an ON period, an ON time sum total and a maximum ON time value based on the generated ON/OFF signal, and an inference means for inferring for each ON period based on the extracted characteristic parameter whether or not an earthquake happens.

Abstract: The current invention is an apparatus useful for generating seismic waves with an enhanced signal to noise ratio. The enhanced signal is produced at a fundamental resonant frequency, and multiples thereof, by producing a near zero acoustic pressure condition around and beyond each end of the apparatus having an intermediate acoustic source. Such a near zero acoustic pressure condition is established preferably by either (1) using two end acoustic sources to produce a destructive interference effect with the acoustic output of a third acoustic source postioned therebetween, or (2) using two active or passive end acoustic capacitors or resonators to produce a near zero impedance condition at each end of the apparatus. The enhanced signal may be produced over a range of frequencies, including both resonant and nonresonant frequencies, by creating a high impedance condition experienced by the intermediate source and hence a high acoustic pressure around the intermediate region of the apparatus.

Abstract: The current invention is an apparatus useful for generating seismic waves with an enhanced signal to noise ratio. The enhanced signal is produced at a fundamental resonant frequency, and multiples thereof, by producing a near zero acoustic pressure condition around and beyond each end of the apparatus having an intermediate acoustic source. Such a near zero acoustic pressure condition is established preferably by either (1) using two end acoustic sources to produce a destructive interference effect with the acoustic output of a third acoustic source postioned therebetween, or (2) using two end acoustic capacitors or resonators to produce a near zero impedance condition at each end of the apparatus. The enhanced signal may be produced over a range of frequencies, including both resonant and nonresonant frequencies, by creating a high impedance condition experienced by the intermediate source and hence a high acoustic pressure around the intermediate region of the apparatus.

Abstract: A marine seismic bottom geophone anchor and coupling device comprising two rectangular fabric sections attached along their edges and along a plurality of lines between edges to form a plurality of pockets. The pockets are filled with a weighting material. Connecting means are provided so that when the combined fabric sections are wrapped around a marine seismic bottom geophone, it will be held in a generally cylindrical form to simultaneously anchor the geophones and associated cables at a desired marine bottom location, isolate the sensors from noise sources, and provide good coupling to the marine bottom for receiving desired seismic signals.

Abstract: A source for emission of seismic energy waves into subsurface earth formations is provided with electrically energizable signal generators mounted between two plate members. One of the plate members is anchored to the earth surface and the other rests on and is coupled with the earth surface. The source is easily movable between shotpoint locations and provides controllable seismic signals of improved bandwidth and quality.

Abstract: A seismic detector for boreholes is described that has an accelerometer sensor block for sensing vibrations in geologic formations of the earth. The density of the seismic detector is approximately matched to the density of the formations in which the detector is utilized. A simple compass is used to orient the seismic detector. A large surface area shoe having a radius approximately equal to the radius of the borehole in which the seismic detector is located may be pushed against the side of the borehole by actuating cylinders contained in the seismic detector. Hydraulic drive of the cylinders is provided external to the detector. By using the large surface area wall-locking shoe, force holding the seismic detector in place is distributed over a larger area of the borehole wall thereby eliminating concentrated stresses.

Abstract: A device including instruments for use on the seabed for the collection and recording of first signals during off-shore seismic exploration.

Abstract: The method of implanting a geophone in the earth including the steps of drilling a borehole in the earth, pumping grout into the borehole, pumping a geophone down the interior of a cylindrical pipe positioned in the borehole, the end of the pipe being adjacent the desired point of implantation of the geophone, and pumping additional grout into the borehole to completely surround the geophone and allow the grout to solidify. In one embodiment, a tubular drill pipe having a severable drill bit at the lower end is first used to drill a borehole, after which the drill bit is hydraulically severed from the tubular drill pipe and the grout and the geophone are pumped down into the hole through the interior of the drill pipe.

Abstract: A sonde for acquiring seismic signals in a borehole, the sonde comprising: a detector module (30) enclosing at least one seismic sensor (G); an elongate body (21) having a lateral cavity (22) suitable for receiving the detector module (30); a resislient suspension (40, 50) connecting said module to said body; and an anchor member (12, 13) disposed on the opposite side of said body to the side in which said cavity is disposed. The sonde is characterized by the fact that the resilient suspension exerts a force on said module suitable for displacing it out from the cavity and for pressing it against the wall of the borehole so as to couple it to said wall, together with means (41, 43, 51, 53, 60) which are provided to retract the module into said cavity against the force exerted by the resilient suspension.

Abstract: A borehole seismic tool including a borehole clamp which only moves perpendicular to the borehole. The clamp is driven by an electric motor, via a right angle drive. When used as a seismic receiver, the tool has a three part housing, two of which are hermetically sealed. Accelerometers or geophones are mounted in one hermetically sealed part, the electric meter in the other hermetically sealed part, and the clamp and right angle drive in the third part. Preferably the tool includes cable connectors at both ends. Optionally a shear plate can be added to the clamp to extend the range of the tool.

Abstract: A seismic system is placed in a predetermined orientation with respect to a surface of a formation, and a low viscosity substance is introduced between the sensor system and the surface of the formation. The substance has a composition formulated for stiffening in situ by increasing viscosity to provide a mechanical bond and an acoustical signal transmission coupling between the sensor system and the formation. After completion of the seismic operation, the stiffened substance is contacted with a stimulus for breaking the stiffened substance and thereby break the mechanical bond. Thereafter, the sensor system is recovered.

Abstract: A device and method for suppressing acoustic tube wave noise in a borehole. The device comprises an absorptive material that is positioned in a borehole so that the device will encounter and absorb the tube waves before the waves are detected by receivers. The device can also contain a housing in which to place the absorptive material. The housing can also be surrounded by an absorptive material to help absorb energy reflecting off the borehole wall.

Abstract: A seismic receiver array device for shallow water and near-shore operations which is comprised of an elongated low-profile, flexible casing having a plurality of geophones and hydrophones spaced along its length, and the geophones and hydrophones are electrically connected to a transmitter for transmitting the seismic impulses into a master receiver. Spikes are extended downwardly at spaced intervals along the length of the casing and a setting tool is provided to releasably anchor the spikes into the earth below a body of water.

Abstract: A method and apparatus for providing shear waves in a marine environment in which a shear wave source penetrates the surface sediment of a water bottom. The shear wave generating source includes an actuator/reaction mass system mounted inside a structural ring of a housing section. A cross-shaped structure at the top of the apparatus serves as a passive reaction mass and as a moment arm support for reversibly motor driven propellers enclosed in shrouds at the outer ends of the structure. A thruster system provides dynamic positioning. The cross-shaped structure and housing section are connected by a structurally stiff member, such as a vertical tube. Pistons provide actuation against a reaction mass located within the housing structure, and motion of the housing structure generates shear waves which propagate in the subsurface formations.

Abstract: A geophone configuration is disclosed that includes an elongated extension or spike that couples with the soil in the hole made by the spike in the region near the end of the spike without hard or firm coupling with the soil above that region. A bow spring or drill bit larger in diameter than the diameter of the spike can be used for achieving predominant contact for the coupled region compared to soil opposite the remainder of the spike. Alternately, a weighted tip can be employed to achieve relative superior coupling by weight compared with the less heavy region of the spike above such weighted tip.

Abstract: A signal receiving system adapted to be lowered into a drilling and suspended from an electro-bearer cable and adapted to be coupled with walls of the drilling so as to receive signals propagating in the surrounding formations. One or more expansible chambers are interconnected by ducts and suspended under a rigid body connected to the surface by the electro-bearer cable. Each expansible chamber includes flexible side walls into which are integrated at least one receiving element. The expansible chambers are adapted to be expanded by injecting a compressed fluid produced by a hydraulic system contained in the rigid body. The receiving elements are connected to a signal acquisition device disposed in the rigid body which communicates with a laboratory truck on a surface.

Abstract: A method for high-resolution seismic recording with increased bandwidth using detectors planted at shallow depths below the earth's surface. In one embodiment, an optimum depth where the amplitudes of high frequency signals increase relative to that of the noise during high-resolution recording is determined, geophones are then planted at that optimum depth and signals are recorded at that depth. To find this optimum depth, detectors are planted at various depths below the earth's surface in order to record the signals at those various depths. The frequency spectra for each detected signal is generated and a velocity profile of the depths covered by the detectors is also generated from the signals. The bandwidth of the frequency spectra and the velocity profile are used to determine a depth for planting the detectors that is closer to the earth's surface than the depths previously considered.

Abstract: An apparatus and method of high resolution reverse vertical seismic profile (VSP) measurements is shown. By encapsulating the seismic detector and heaters in a meltable substance (such as wax), the seismic detector can be removably secured in a borehole in a manner capable of measuring high resolution signals in the 100 to 1000 hertz range and higher. The meltable substance is selected to match the overall density of the detector package with the underground formation, yet still have relatively low melting point and rigid enough to transmit vibrations to accelerometers in the seismic detector. To minimize voids in the meltable substance upon solidification, the meltable substance is selected for minimum shrinkage, yet still having the other desirable characteristics. Heaters are arranged in the meltable substance in such a manner to allow the lowermost portion of the meltable substance to cool and solidify first.

Abstract: A seismic signal receiving system is provided for use in boreholes to receive seismic waves in carrying out geophysical investigations. The system includes three pairs of opposed plates, each of the pairs of plates including oppositely facing outer surfaces for engagement with opposite sides of a borehole. A seismic receiver is mounted on the inner surface of each of the plates for receiving seismic signals. A double-acting, fluid-operated actuator selectively causes relative movement of the plates of the pairs of plates away from each other to provide expansion thereof so as to enable the plates to engage the walls of a borehole and selectively causes relative movement of the plates of the pairs of plates toward each other to provide retraction thereof so as to enable the system to be removed from a borehole. The pairs of plates each comprise a relatively long plate and a relatively short plate. An expandable linkage interconnects the long plates at the distal ends thereof.

Abstract: A downhole seismic exploration device comprises a seismic detector such as a geophone and a magnetic clamp, supported by O-rings in an open cradle carrier which can be secured to a cable linking several such devices into an array. The array is lowered into a cased borehole and the magnetic clamps are operated to clamp the devices temporarily to the casing. Seismic signals detected by the geophones are transmitted to the surface via the cable, the O-ring supports acting to reduce or eliminate transmission of vibrations from the borehole fluid and the cable via the carrier to the geophone. The array is then unclamped and moved to another location in the borehole and the operation repeated. The magnetic clamp comprises a rotatable permanent magnet with radial poles disposed between a pair of parallel pole piece plates protruding on each side of the device and separated by non-magnetic blocks on eahc side of the magnet.

Abstract: A sensor module having tri-axial spatial sensitivity is mounted in a closed compartment of an acoustic logging tool. The sensor module is resiliently mounted with three degrees of freedom with respect to the body of the tool. The compartment includes a volume of damping fluid to suppress parasitic vibrations transmitted to the sensor module from the tool body. In the inactive condition, a contact shoe, associated with the sensor module, projects through a window in the closed compartment. In the operating configuration, the sensor module and its contact shoe are caused to retract into the compartment against a compressive force when the logging tool is pressed against the wall of a borehole.

Abstract: Method and apparatus for generating seismic energy in offshore areas includes energy propagating means for directing energy downwardly vertically into an earth formation. A carrier contains an elongated rigid coupler means that extends from the carrier at the water level to the seat floor. A base plate may be connected to the lower end of the coupler means. The coupler means may be a section of pipe. Driving means on the carrier drives the coupler means to cause sound energy to emanate from the coupler means or base plate into the sea floor. Such means may be a hammer-type device or a vibrator-type device. Alternatively, the lower end of the coupler means or the base plate may be driven by means of a vibrator-type device to cause sound waves to emanate from the coupler means or the base plate directly into the sea floor.

Abstract: Apparatus for carrying and positioning seismic detector equipment down a cased borehole and which includes a three component signal detector, azimuth sensing equipment and a particular type of borehole clamping arrangement that includes a combination of serrated locking pads, a contact rod and an inflatable bladder functioning in three point contact. An apparatus results that assures an improved form of three component geophone array that is lighter, easier handled and more reliably clamped within a borehole while having the additional azimuth sensing capability.

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 light weight and compact geophone assembly for detecting transient seismic signals along orthogonal axes. The geophone assembly having a plurality of geophones arranged within close proximity of each other within a compact housing. The geophones are interconnected to a conductor cable passing through the housing in a unique water-tight sealing arrangement. At the cable entrance into the housing, the conductor cable is surrounded by a tapered boot compressed about the cable by a sleeve which in turn is fixed in place by a locking nut. The locking nut is received by complementary threads at the cable entrance into the housing. When tightened, the locking nut forces the compression sleeve over the tapered surface of the boot, compressing the boot about the cable. In addition, the locking nut and compression sleeve urge the boot in compression between the cable and the housing. Located atop of the housing is a bubble leveling device.

Abstract: A sonde for aquiring seismic signals in a borehole, the sonde comprising: a detector module (30) enclosing at least one seismic sensor (G); an elongate body (21) having a lateral cavity (22) suitable for receiving the detector module (30); a resilient suspension (40, 50) connecting said module to said body; and an anchor member (12, 13) disposed on the opposite side of said body to the side in which said cavity is disposed. The sonde is characterized by the fact that the resilient suspension exerts a force on said module suitable for displacing it out from the cavity and for pressing it against the wall of the borehole so as to couple it to said wall, together with means (41, 43, 51, 53, 60) which are provided to retract the module into said cavity against the force exerted by the resilient suspension.

Abstract: An elongate multilink compound suspension arm is set forth for positioning a sensor parallel to and spaced from a sonde. In particular, it includes first and second approximately parallel arms pivotally connected to a third arm. There are control members additionally included which may be pushed or pulled as appropriate to cause extension arm assembly to move from a fully retracted position in a receptacle along the sonde to an angle extended outwardly and to the rear of the sonde. A sensor pad is supported at the back end and extends toward the back end of the sonde. The sensor pad is pivotally mounted, and is connected with a resilient means for urging the sensor pad into facial contact with the side wall of the borehole. The multilink system particularly enables the sensors on the sensor pad to maintain facial contact with the borehole at a variable distance from the sonde and parallel or at appropriate angles relative to the central axis of the sonde.