A detection system includes a drill bit where electro-acoustic transducers operate as a transmitter and/or receiver, are integrated; electronic circuits; a control unit associated with a data storage unit and is powered by an electrical supply system, the processing and control unit for generating driving signals sent to the electro-acoustic transducer acting as a transmitter by the analogue driving electronic circuits, for acquiring signals received from the transducer and for processing the received signals to determine discontinuity interfaces and/or anomalies in pore pressures in geological formations; wherein each of the electro-acoustic transducers is in contact with a pressurised fluid and includes: a tubular body with two end portions opposed to each other longitudinally, internally a first chamber with the first end portion and a second chamber on one side adjacent and in fluid communication with the first chamber and, on the other side ending with the second end portion.

Aspects of the invention include arranging two cylindrical magnets with transverse magnetization to be parallel to each other along their longitudinal axis. The two cylindrical magnets have a space between them and are prevented from moving relative to one another. An exemplary method includes disposing a diamagnetic object to levitate above the space between the two cylindrical magnets. A motion detector is arranged to identify relative movement between the two cylindrical magnets and the object, and an infrasound wave is identified based on the relative movement.

Aspects of the invention include arranging two cylindrical magnets with transverse magnetization to be parallel to each other along their longitudinal axis. The two cylindrical magnets have a space between them and are prevented from moving relative to one another. An exemplary method includes disposing a diamagnetic object in the space between the two cylindrical magnets, wherein the object levitates above the space. A motion detector is arranged to identify relative movement between the two cylindrical magnets and the object, and an infrasound wave is identified based on the relative movement.

A detection system includes a drill bit where electro-acoustic transducers operate as a transmitter and/or receiver, are integrated; electronic circuits; a control unit associated with a data storage unit and is powered by an electrical supply system, the processing and control unit for generating driving signals sent to the electro-acoustic transducer acting as a transmitter by the analogue driving electronic circuits, for acquiring signals received from the transducer and for processing the received signals to determine discontinuity interfaces and/or anomalies in pore pressures in geological formations; wherein each of the electro-acoustic transducers is in contact with a pressurised fluid and includes: a tubular body with two end portions opposed to each other longitudinally, internally a first chamber ending with the first end portion and a second chamber on one side adjacent and in fluid communication with the first chamber and, on the other side ending with the second end portion.

A self-damping geophone, in some embodiments, comprises a housing containing a conductive coil and one or more springs; a first magnet suspended within said housing by the one or more springs, said conductive coil located within a magnetic field of the first magnet; and damping magnets disposed outside of said housing, each of the damping magnets oriented to repel a pole of the first magnet closest to that damping magnet.

A geophone includes a magnet, an electrical coil assembly, and a tubular case. The electrical coil assembly is disposed about the magnet, and is movable in an axial direction with respect to the magnet. The electrical coil assembly includes a coil, a first spring disposed at a first end of the electrical coil assembly, and a second spring disposed at a second end of the electrical coil assembly. The first spring and the second spring are configured to produce a natural frequency of 9 Hertz to 12.5 Hertz in oscillation of the coil about the magnet. The magnet and the coil assembly are coaxially disposed within the tubular case. The tubular case is no more than 1.7 inches in length. The electrical coil assembly is configured to move in an axial direction with respect to the magnet in any orientation of the tubular case.

A seismometer with high sensitivity, broadband and all-dip is provided, The which relates to the technical field of seismometer, including a first force feedback module, an insulator, a top cover, a terminal post, an upper leaf spring, a mass block, a casing, a sealing ring, an insulation gasket, a guide spring, a wire frame, a magnetic shoe, a compensation ring, a lower leaf spring, a bottom cover, a second force feedback module and a third force feedback module. It provides the broadband seismometer technology based on dynamic force balance feedback and the all-dip broadband seismometer technology based on dip angle perception, which breaks through the limitations of conventional seismometers in sensitivity, frequency band, and dip angle, and truly realizes a seismometer with high sensitivity, broadband, and all-dip.

A dual core geophone includes a dual magnetic core packaged in a housing providing higher sensitivity and a reduction of electric wires in the device. The geophone includes a locking mechanism for the dual magnetic core to protect the device from strong vibrations when the device is not in use. A method for measuring acoustic vibrations in a downhole with a dual core geophone as above includes locking the dual magnetic core when the geophone is not detecting acoustic vibrations.

A self-damping geophone, in some embodiments, comprises a housing containing a conductive coil and one or more springs; a first magnet suspended within said housing by the one or more springs, said conductive coil located within a magnetic field of the first magnet; and damping magnets disposed outside of said housing, each of the damping magnets oriented to repel a pole of the first magnet closest to that damping magnet.

An illustrative geophone with tunable resonance frequency includes a first inductive assembly including an inductive coil having a first magnet arranged therein, wherein the first magnet and the first inductive coil move relative to each other, and a second inductive assembly including a second inductive coil having a second magnet arranged therein, wherein the second magnet and the second inductive coil move relative to each other. A coupling element couples a movable element of the first inductive assembly with a moveable element of the second inductive assembly. The first inductive assembly employs tunable damping to modify a resonant frequency of the second inductive assembly.