Abstract: Thin flexible piezoelectric transducers are bonded to or imbedded into oilfield tubular members or structural members. The transducers may be used to telemeter data as acoustic waves through the members. By proper spacing of transducers and phasing of driving signals, the transmitted signals can be directionally enhanced or encoded to improve transmission efficiency. The transducers may be used for health monitoring of the tubular or structural members to detect cracks, delaminations, or other defects. The flexible transducers are very thin so that overall dimensions of tubular or structural members are essentially unchanged by incorporation of the transducers.

Abstract: A slickline data transmission system for a high pressure oil-field well comprises inductive couplers at opposite ends of a slickline in order to establish real-time radio communication between down-the-hole logging toolstrings and supervisory control and data acquisition equipment on the surface. A frequency shift keyed (FSK) carrier centered around radio is used to send data up to the surface and commands back down to the toolstring. The toolstring itself can be a conventional one with a TDMA interface originally intended to be memory-dumped when the toolstring is returned to the surface.

Abstract: A repeater is disclosed in one embodiment of the present invention as including a cylindrical housing, characterized by a proximal end and a distal end, and having a substantially cylindrical wall, the cylindrical wall defining a central bore passing therethrough. The cylindrical housing is formed to define at least one recess in the cylindrical wall, into which a repeater is inserted. The cylindrical housing also includes an annular recess formed into at least one of the proximal end and the distal end. An annular transmission element, operably connected to the repeater, is located in the annular recess. In selected embodiments, the annular transmission element inductively converts electrical energy to magnetic energy. In other embodiments, the annular transmission element includes an electrical contact to transmit electrical energy directly to another contact.

Abstract: A signaling apparatus comprises a magnet and a shield moveable relative to the magnet. The shield is moveable relative to the magnet between a first position in which the magnet is relatively exposed and a second position in which the magnet is relatively shielded. The apparatus can include a synchronization signal source, a downhole sensor signal source, and/or means for modulating the magnetic field in response to the signal from any source. A method of using the signaling apparatus to locate a bottomhole assembly includes moving the shield so as to modulate the magnetic field created by the magnet, sensing the modulation of the magnetic field, and determining the location of the bottomhole assembly using the information collected. The BHA can be located using phase shift or amplitude measurements. Receivers detecting the modulated magnetic field can be at or below the earth's surface.

Abstract: A casing sensor and methods for sensing using a casing sensor are disclosed. The casing sensor includes a casing shoe and a sensor coupled to the casing shoe. A casing data relay includes a downhole receiver coupled to a well casing and a transmitter coupled to the receiver. The casing sensor may be coupled to the transmitter. A drill string actuator may be controllable through the downhole receiver.

Abstract: Telemetry systems and methods are disclosed for real time communication of information between multiple positions in a wellbore.

Abstract: The invention includes a wireless communication circuit and a method of communicating with wireless signals that feature a tank circuit having an inductor connected in parallel with a capacitor circuit. The capacitor circuit includes a pair of capacitors coupled in series. Each of the capacitors is connected in common to ground and has a capacitive value associated. A feedback network is connected to selectively bias the tank circuit to produce a signal having an amplitude. The amplitude of the signal is a function of a ratio of the capacitive values associated with the capacitor circuit. The frequency of the signal is defined by the inductor and the capacitor circuit. The tank circuit is multifunctional in that it may be biased to function as a transmitter and a receiver.

Abstract: Acoustic telemetry devices and methods that provide directional detection. In one embodiment, a disclosed acoustic telemetry device comprises at least two acoustic sensors and an electronics module. A first of the acoustic sensors detects a communication signal that propagates along a tubing string in a first direction. A second of the acoustic sensors is configured to detect the communication signal before the first acoustic sensor. The electronics module combines the detection signals from the acoustic sensors to obtain a combined signal that substantially excludes signals propagating in a direction opposite to the communication signal. Such signal suppression may significantly enhance the communication signal's signal-to-noise ratio, thereby increasing channel capacity. The acoustic telemetry device may be configured to support logging while drilling and/or full-duplex communication.

Abstract: A power delivery system for a wireline tool includes two independent power transmission loops operating on a standard six-conductor cable. The two loops each connect directly to a respective terminals of a DC auxiliary power supply. Each loop also couples through a transformer to an AC instrument power supply. Another transformer for telemetry signals facilitates bidirectional communication between the downhole tool and an uphole computer.

Abstract: The preferred pulser is a mud powered oscillator powered by the pressure variation produced across the signal valve by the unstable action. The signal valve comprises a poppet and cooperating orifice. The pressure drop across the orifice is used to urge the poppet away from the orifice and an opposing spring drives it toward the orifice. The preferred poppet control is a permanent magnet that secures the poppet in at least the signal valve open position. To generate a pulse, the permanent magnet is opposed by a magnetizing coil arranged and powered by the associated MWD instrument to oppose the permanent magnet, to release the poppet to close the signal valve. The pulser is arranged to provide a generally central axially extending bore to accept a conductor extending axially through the pulser. Optional features include an acceleration compensator, and a mud powered electric energy generator. Optional features include hydraulic actuation and control of the poppet.

Abstract: An electromagnetic borehole telemetry system for transmitting information between a borehole transceiver and a surface transceiver located at or near the surface of the earth. Tubulars, such as steel casing and liners, are typically set within the well borehole to stabilize the wall of the borehole and to assist in hydraulically isolating penetrated formations. The invention utilizes these tubulars cooperating with one or more signal wires to reduce attenuation and noise in signals transmitted between the borehole and surface transceivers. The one or more signal wires are typically disposed within an annulus formed by the borehole wall and the outside surface of the casing. The one or more signal wires are connected at one end to one or more connection terminals positioned preferably near the bottom a tubular string. Opposing ends of the one or more signal wires are connected to one or more terminals of the surface transceiver.

Abstract: An apparatus for electromagnetically connecting surface equipment to a rotating downhole tool string comprises a plurality of electrical conductors, first and second differential interfaces, and at least one electromagnetic shield. The plurality of electrical conductors have first ends terminating at the surface equipment and second ends terminating at the downhole tool string. The first differential interface is electrically connected to the first ends and the second differential interface is electrically connected to the second ends the electrical conductors. The first and second differential interfaces are adapted to transmit and receive a reference-independent differential signal. The electromagnetic shield surrounds and shields the electrical conductors and is connected to ground at one end. The apparatus is stationary relative to rotation of the tool string.

Abstract: A method and a downhole telemetry system a downhole telemetry system using discrete multitone modulation for transmitting a data stream over a plurality of transmission modes is provided. The downhole telemetry system includes a downhole transmitter, a cable, and a surface receiver. The downhole transmitter is configured to transmit the data stream over the plurality of transmission modes. The surface receiver is coupled to the downhole transmitter via the cable and is configured to combine signals from each of the plurality of transmission modes to obtain the data stream transmitted by the downhole receiver. The method includes receiving a plurality of signals over the plurality of transmission modes from a downhole package, and may further include combining the plurality of signals to form at least one data stream.

Abstract: An electromagnetic borehole telemetry system for transmitting information between a borehole transceiver and a surface transceiver located at or near the surface of the earth. Tubulars, such as steel casing and liners, are typically set within the well borehole to stabilize the wall of the borehole and to assist in hydraulically isolating penetrated formations. The invention utilizes these tubulars cooperating with one or more signal wires to reduce attenuation and noise in signals transmitted between the borehole and surface transceivers. The one or more signal wires are typically disposed within an annulus formed by the borehole wall and the outside surface of the casing. The one or more signal wires are connected at one end to one or more connection terminals positioned preferably near the bottom a tubular string. Opposing ends of the one or more signal wires are connected to one or more terminals of the surface transceiver.

Abstract: A petroleum well having a borehole extending into a formation is provided. A piping structure is positioned within the borehole, and an induction choke is positioned around the piping structure downhole. A communication system is provided along the piping structure between a surface of the well and the induction choke. A downhole module is positioned on an exterior surface of the piping structure and is configured to measure characteristics of the formation. The formation characteristics, such as pressure and resistivity, are communicated to the surface of the well along the piping structure.

Abstract: A signal transmission connection for a tool string used in exploration and production of natural resources, namely: oil, gas, and geothermal energy resources. The connection comprises first and second annular elements deployed in cooperative association with each other. The respective elements comprise inductive transducers that are capable of two-way signal transmission between each other, with downhole components of the tool string, and with ground-level equipment. The respective inductive transducers comprise one or more conductive loops housed within ferrite troughs, or within ferrite trough segments. When energized, the conductive loops produce a magnetic field suitable for transmitting the signal. The second element may be rotational in drilling applications. The respective elements may be fitted with electronic equipment to aid and manipulate the transmission of the signal. The first element may also be in communication with the World Wide Web.

Abstract: An insulator for a subsurface signal transmitting apparatus. The insulator includes a housing, a mandrel axially disposed inside the housing, a first insulating material disposed between the housing and the mandrel, a first sleeve formed of a second insulating material disposed between the housing and a first tubular member and the first tubular member coupled to the mandrel.

Abstract: A telemetry system and method for communicating information axially along a drill string comprised of a drive train supported within a housing. The system includes an axial conducting loop formed by the drill string for conducting an axial electrical signal embodying the information between a first axial position and a second axial position in the drill string, which axial conducting loop extends between the first and second axial positions. A transmitter transmits information to the axial conducting loop. The drive train includes a downhole end which extends from and is located below the housing. At least one of the first and second axial positions is located in the downhole end. The method includes the step of conducting the axial electrical signal between the first and second axial positions through the axial conducting loop which extends between the first and second axial positions.

Abstract: A petroleum well for producing petroleum products that incorporates a system adapted to provide power to a downhole device in the well. The system includes a current impedance device and a downhole power storage device. The current impedance device is positioned such that when a time-varying electrical current is transmitted through the portion of a piping structure and/or a voltage potential forms between one side of the current impedance device and another side of the current impedance device. The device is adapted to be electrically connected to the piping structure and/or across the voltage potential formed by the current impedance device, is adapted to be recharged by the electrical current, and is adapted to be electrically connected to the downhole device to provide power to the downhole device as needed.

Abstract: Data transmission in pipeline systems A first set of apparatus is arranged for transmitting data from a point in a cased section of a well 1, 3 to a remote location. The apparatus may be used as a relay station 6 to increase operational depth. Signals are applied to and received from the string 1 at the relay station 6 and a selected length of the string 1 is provided with insulating spacer means 9 on either side of the relay station to ensure that the string 1 and casing 3 are effectively isolated for a selected minimum distance. This enables potential differences to be both applied to and detected from the string 1, thus allowing data transmission and reception. A second set of apparatus is arranged for transmitting from an internal unit 408 inside a cased section of the well 401, 403 to the immediate surrounding area outside the casing 403. The internal unit 408 injects current into the string 401. A toroid 415 which surrounds the casing 403 is provided to pick up signals.

Abstract: A drill pipe forms an acoustic transmission channel for data to be transmitted from a downhole transceiver to a surface transceiver. By positioning a first low frequency acoustic attenuator between a drill bit and the downhole transceiver, acoustic noise generated by the drill bit is attenuated. Similarly, by positioning the surface transceiver between the top of the drill pipe and a second low frequency acoustic attenuator, acoustic noise generated by surface equipment is attenuated. In this manner, the first and second low frequency acoustic attenuators serve as terminators for the acoustic transmission channel.

Abstract: A robust transmission element for transmitting information between downhole tools, such as sections of drill pipe, in the presence of hostile environmental conditions, such as heat, dirt, rocks, mud, fluids, lubricants, and the like. The transmission element maintains reliable connectivity between transmission elements, thereby providing an uninterrupted flow of information between drill string components. A transmission element is mounted within a recess proximate a mating surface of a downhole drilling component, such as a section of drill pipe. The transmission element may include an annular housing forming a trough, an electrical conductor disposed within the trough, and an MCEI material disposed between the annular housing and the electrical conductor.

Abstract: Methods and systems for borehole telemetry are disclosed. In one embodiment, a borehole telemetry system includes a coiled tubing string that is located in the borehole. A receiver is coupled to the coiled tubing string. In one possible implementation, the receiver is located inside the coiled tubing string. A transmitter is also coupled to the coiled tubing string. The transmitter generates signals guided for at least a portion of their path by the entire internal cross-section of the coiled tubing string to the receiver.

Abstract: The present invention generally provides a downhole tool with an improved means of transmitting data to and from the tool through the use of wired pipe capable of transmitting a signal and/or power between the surface of the well and any components in a drill string. In one aspect, a downhole tool includes a body, and a mandrel disposed in the body and movable in relation to the body. A conducive wire runs the length of the body and permits signals and/or power to be transmitted though the body as the tool changes its length.

Abstract: Apparatus and methods to improve signal coupling in downhole inductive transmission elements to reduce the dispersion of magnetic energy at the tool joints and to provide consistent impedance and contact between transmission elements located along the drill string. A transmission element for transmitting information between downhole tools is disclosed in one embodiment of the invention as including an annular core constructed of a magnetically conductive material. The annular core forms an open channel around its circumference and is configured to form a closed channel by mating with a corresponding annular core along an annular mating surface. The mating surface is polished to provide improved magnetic coupling with the corresponding annular core. An annular conductor is disposed within the open channel.

Abstract: An electromechanical transducer formed by an electrical and mechanical combination of a piezoelectric device and a magnetostrictive device. The two devices are electrically coupled so that their capacitive and inductive reactances approach a balance to provide an essentially resistive combined input at a selected frequency. Efficiency of circuits driving the transducer is improved. The devices are mechanically coupled so that the mechanical outputs add or reinforce each other. Two transducer pairs may be used in a two frequency telemetry system with each pair tuned to one of the frequencies for optimal reactance balancing and transduction efficiency.

Abstract: Systems and methods utilizing an elongated sub body adapted to receive a run-in tool within its inner bore. The run-in tool including nuclear sources and sensors to provide nuclear formation evaluation while tripping. The nuclear sources and sensors align with partially or fully penetrating windows in the sub to allow for measurements through the sub. The sub wall includes an inner passage adapted to direct radiation energy emitted from within the sub back to the sub bore to align the run-in tool within the sub. The sub also includes fully penetrating openings in its walls to provide through-tubular signal passage. Hydraulic isolation at the sub openings is provided by pressure barrier means. A run-in tool configuration also includes antennas, neutron, and gamma-ray sources/sensors to provide a retrievable triple combo system.

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: Systems and methods for downhole communication and measurement utilizing an improved metallic tubular having an elongated body with tubular walls and a central bore adapted to receive a run-in tool. The tubular including slotted stations to provide through-tubular signal transmission and/or reception. Hydraulic isolation between the interior and exterior of the tubular is provided by pressure barrier means at the slotted stations. Sensors and/or sources are mounted on the run-in tool, which is adapted for transmission through a drill string to engage within the tubular in alignment with the slotted stations. A run-in tool configuration includes a modulator for real-time wireless communication with the surface and/or remote downhole tools. A tubular and run-in tool configuration also includes inductive couplers for wireless signal data transfer. A method for measuring a formation characteristic utilizing a run-in tool adapted with an interchangeable end segment for multi-mode downhole transport.

Abstract: An apparatus for monitoring conditions in subterranean borehole during drilling and pullback operations in real time. The apparatus includes a drill string having a working end. A measurement system suitable for measuring at least one operational characteristic of the apparatus and having a metallic section in direct contact with the drill string is operably connected to the working end of the drill string. At least one toroid is circumferentially disposed around a first portion of the metallic section and has toroidal electrically conductive windings. A non-conductive material is disposed around the toroid whereby contact between the toroid and a subterranean environment during operation of the apparatus is precluded.

Abstract: A signal repeater, a system utilizing one or more signal repeaters, and a method for detecting a transient disturbance in the surface charge on drill pipe, which system, apparatus and method are collectively used to transfer data from deep-well and high-conductivity formation subterranean environments to a point nearer to the surface. The signal repeater comprises a housing that is securably mountable to the interior of a pipe-string disposed in a wellbore, which repeater receives and stores electrical signals for resending at an appropriate time.

Abstract: A system and method of communicating among devices via a piping structure using at least one induction choke about the piping structure to route a time-varying current carrying communication signals between the devices. A communications system comprises a piping structure, a first communication device, a second communication device, and an induction choke. The piping structure comprises a first location, a second location, and an electrically conductive portion extending between the first and second locations. The first and second locations are distally spaced along the piping structure. The first and second communication devices are each electrically connected to the electrically conductive portion of the piping structure along the first location and second location, respectively, and each is adapted to send and receive communication signals via time-varying current.

Abstract: The invention relates to an apparatus for receiving downhole acoustic signals, processing the signals into electric signals, then transmitting the signals wirelessly to a remote above-surface monitoring station. The apparatus is mountable to an above-surface rotatable component used in borehole application. The apparatus includes an instrument housing, and a clamping assembly attached to the housing and having sufficient length and flexibility to enable the apparatus to surround the perimeter of the rotatable component.

Abstract: The invention relates to a hollow drilling rod for transmitting information, said rod being for placing in a borehole filled with drilling mud. The rod comprises an electrically conductive cylindrical wall (521, 522) having an inside face, an outside face, a first end provided with a male coupling sleeve (62), and a second end provided with a female coupling sleeve (60), and being characterized in that it further comprises: a layer of electrically insulating material (70) covering the inside face over its entire length; and a conductive layer (80) covering said insulating layer and electrically connected at its ends to two electrically conductive rings, said conductive layer itself being covered by a second insulating layer (86) leaving said conductive rings in contact with the drilling mud.

Abstract: A power transmission and data communications system for use in a gas or oil well borehole is disclosed. The borehole includes a casing and a piping structure therein and at least one downhole equipment module located therein. The system provides for a power signal to provide power transfer to downhole systems that require power and for data and control signals to be transmitted using orthogonal frequency division multiplexing (OFDM) to the downhole equipment located in the downhole equipment modules. In particular, the system provides for the data signal to be electrically coupled to the case and piping structure for transmission downhole to the downhole systems that are similarly coupled to the casing and piping structure. The downhole equipment includes a power supply that is operative to recover electrical power from the power signal and to provide output power to the other downhole equipment.

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: 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: Data is transmitted along a borehole containing a drill stem (2) by means of a transmitter (6) which converts electric data signals to acoustic signals propagating along the drill stem (2). The acoustic signals are converted back to electric form by a receiver (12) which also processes the signals. In the preferred form the signals are stored in a receiver memory (15) for subsequent retrieval using a pick-up tool (5) lowered into the borehole. The system is particularly useful in moving data past an obstruction such as a shut-in valve (4).

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: The present disclosure provides several methods for selecting and transmitting information from downhole using more than one channel of communication wherein data streams transmitted up each communications channel are each independently interpretable without reference to data provided up the other of the communications channels. Preferred embodiments incorporate the use of a combination of at least two of mud-based telemetry, tubular-based telemetry, and electromagnetic telemetry to achieve improved results and take advantage of opportunities presented by the differences between the different channels of communication.

Abstract: A reprogrammable data communications system for use in a gas or oil well borehole is disclosed. The borehole includes a casing and a piping structure therein and at least one downhole equipment module located therein. The system provides for data and control signals to be coupled to the casing and piping structure by a surface modem and transmitted to the downhole equipment located in the downhole equipment modules. The downhole equipment modules include a downhole modem that is coupled to the casing and piping structure and receives the transmitted data and command signals and recovers the transmitted data and commands therefrom. A downhole processor is coupled to the downhole modem and receives the data and commands from the downhole modem and stores the data and commands in retentive memory that is coupled to the downhole processor. In this way, the downhole processor can be reprogrammed with new algorithms and communications parameters.

Abstract: A well system having a sensor; a controller for converting the sensor output, a signal conducting mass, an actuator for inducing an acoustic wave the signal conducting mass, a reaction mass, an acoustic wave receiver up-hole, and a processor for processing a signal from the acoustic wave receiver and for delivering the processed signal to an output device.

Abstract: A drill pipe having a box end having a tapered thread, and an internal shoulder and an external face for engagement with a drill pipe pin end having a tapered mating thread, and an external shoulder and an external face adapted for data acquisition or transmission. The relative dimensions of the box and pin ends are precisely controlled so that when the tool joint is made up, a repeatable reference plane is established for transmitting power and tuning downhole sensors, transducers, and means for sending and receiving data along the drill string. When the power or data acquisition and transmission means are located in the tool joint, the dimensions of the tool joint are further proportioned to compensate for the loss of cross-sectional area in order maintain the joints ability to sustain nominal makeup torque.

Abstract: Method and system for subsurface logging utilizing a modified tubular having an elongated body with tubular walls and a central bore adapted to receive a support member. The tubular including slotted stations to provide through-tubular signal passage. Pressure barrier means provide hydraulic isolation at the slotted stations. The support member is equipped with sources or sensors and adapted for engagement within the tubular. The tubular and support member are implemented in combination with retrievable and re-seatable MWD apparatus.

Abstract: System, apparatus, and method of telemetering downhole sensor information to the surface while operations are performed in an oil or gas well using coiled tubing. Data are transmitted on coiled tubing as digital signals encoded in acoustic signals. In one implementation, a stripper packer through which coiled tubing is moved into a well is operated between at least a first state and a second state; and an acoustic communication device responds to operation of the stripper packer such that when the stripper packer is in the first state, the acoustic communication device is decoupled from acoustic communication with the coiled tubing, but when the stripper packer is in the second state, the acoustic communication device is coupled for acoustic communication with the coiled tubing.

Abstract: A first flux-loop inductive coupler element electrically couples with a second flux-loop inductive coupler element. The first flux-loop inductive coupler element comprises a first ring-like core having high magnetic permeability and a conical-section annular first face transverse to the plane of the first core. The first face has a first annular groove separating a first conical-section larger-diameter face and a first conical-section smaller-diameter face. A first coil is wound within the annular groove. The first and second cores form a low-reluctance closed magnetic path around the first coil and a second coil of the second flux-loop inductive coupler element. A first current-loop inductive coupler element electrically couples with a second current-loop inductive coupler element.

Abstract: A petroleum well for producing petroleum products that incorporates a system adapted to controllably route communications and/or electrical power having a time-varying current through a piping structure in the well, and methods of producing petroleum products use such a well, are provided by the present invention. The system comprises a first induction choke, a second induction choke, and a controllable switch. The first induction choke is located about a portion of a first branch of the piping structure. The second induction choke is located about a portion of a second branch of the piping structure. The controllable switch having two switch terminals. A first of the switch terminals I is electrically connected to the piping structure on a junction side of the induction chokes. The first and second branches of the piping structure intersect on the junction side of the induction chokes.

Abstract: An electromagnetic coupling system is disclosed which includes a first electromagnetic transducer sealingly disposed in an outer wall of a tool mandrel, the mandrel adapted to be positioned in a drill collar. A second electromagnetic transducer is sealingly disposed in an interior of a port in the drill collar. The second transducer is positioned so that it is proximate the first transducer when the mandrel is positioned in the drill collar. A third electromagnetic transducer is sealingly disposed in an exterior of the port in the collar. The second and third transducers define a sealed chamber in the port. The second and third transducers are electrically coupled to power conditioning and signal processing circuits disposed in the chamber. A fourth transducer is positioned proximate the third transducer. The fourth transducer is electrically coupled to at least one of a sensor, an external communication line and an external power line.

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 system and method of communicating among devices via a piping structure using at least one induction choke about the piping structure to route a time-varying current carrying communication signals between the devices. A communications system comprises a piping structure, a first communication device, a second communication device, and an induction choke. The piping structure comprises a first location, a second location, and an electrically conductive portion extending between the first and second locations. The first-and second locations are distally spaced along the piping structure. The first and second communication devices are each electrically connected to the electrically conductive portion of the piping structure along the first location and second location, respectively, and each is adapted to send and receive communication signals via time-varying current.