Abstract: An electromagnetic borehole telemetry system providing improved signal to noise ratio. Adaptive filters use noise channels as references to remove noise from the signal channel. Directional detectors provide a signal channel with reduced noise content and improved noise channels with reduced signal content. Directional detectors may be magnetometers aligned with the magnetic field, or antennas aligned with the electric field, of signal or noise sources. Alignment may be performed by beam steering of the outputs of a three-channel detector, which may detect both signal and noise.

Abstract: An electromagnetic borehole telemetry system providing improved signal to noise ratio. Adaptive filters use noise channels as references to remove noise from the signal channel. Multiple noise channels are coupled to series connected adaptive filters for removing each noise source from the signal channel. The order of noise removal is selected to remove the most significant first.

Abstract: An electromagnetic borehole telemetry system providing improved signal to noise ratio. Adaptive filters use noise channels as references to remove noise from the signal channel. Improved sensors provide noise channels with reduced signal content. Motion sensors are used to detect noise and provide a noise channel free of signal content. The motion sensors are shielded from electromagnetic signals to prevent detection of the telemetry signal.

Abstract: An electromagnetic borehole telemetry system providing improved signal to noise ratio. Adaptive filters use noise channels as references to remove noise from the signal channel. Directional detectors provide a signal channel with reduced noise content and improved noise channels with reduced signal content. Directional detectors may be magnetometers aligned with the magnetic field, or antennas aligned with the electric field, of signal or noise sources. Alignment may be performed by beam steering of the outputs of a three-channel detector, which may detect both signal and noise.

Abstract: An electromagnetic borehole telemetry system providing improved signal to noise ratio. Adaptive filters use noise channels as references to remove noise from the signal channel. Directional detectors provide a signal channel with reduced noise content and improved noise channels with reduced signal content. Directional detectors may be magnetometers aligned with the magnetic field, or antennas aligned with the electric field, of signal or noise sources. Alignment may be performed by beam steering of the outputs of a three-channel detector, which may detect both signal and noise.

Abstract: An electromagnetic borehole telemetry system providing improved signal to noise ratio. Adaptive filters use noise channels as references to remove noise from the signal channel. Directional detectors provide a signal channel with reduced noise content and improved noise channels with reduced signal content. Directional detectors may be magnetometers aligned with the magnetic field, or antennas aligned with the electric field, of signal or noise sources. Alignment may be performed by beam steering of the outputs of a three-channel detector, which may detect both signal and noise.

Abstract: An electrically insulating gap subassembly for inclusion in a pipe string (30) comprising a pair of tubular members (90, 98) having an electrically insulating isolation subassembly (94) threadably disposed therebetween is disclosed. The electrically insulating isolation subassembly (94) has an anodized aluminum surface that provides electrical isolation to interrupt electrical contact between the two tubular members (90, 98) such that electromagnetic waves (46, 54) carrying information may be generated thereacross.

Abstract: A system and method of fail safe communication of information between surface equipment and downhole equipment are disclosed. The system comprises two or more repeaters (34, 35, 36) disposed within a wellbore (38) such that two repeaters (34, 35) will receive each signal carrying information that is telemetered. The repeater (35) that is farther from the source (44) will include a memory device (292) that stores the information carried in the signal. A timer device (293) also in the repeater (35) that is farther from the source (44) will trigger the retransmission of the information after a predetermined time period unless the repeater (35) that is farther from the source (44) has detected a signal carrying the information generated by the repeater (34) that is closer to the source (44).

Abstract: An electromagnetic pickup apparatus (46) and method for use of the same is disclosed. The apparatus (46) comprises a probe (60) that is insertable into a bore hole (64) or a trench (70) and a conductive backfill composition (62) that substantially surrounds the probe (60) having intimate contact with the probe (60) and the earth, thereby establishing a highly electrically conductive region (66) between the probe (60) and the earth.

Abstract: A downhole communications system including an electromagnetic-to-acoustic signal repeater (35) for communicating information between surface equipment and downhole equipment and a method for use of the repeater (35) is disclosed. The repeater (35) comprises an electromagnetic receiver (37) and an acoustic transmitter (41). The receiver (37) receives an electromagnetic input signal and transforms the electromagnetic input signal to an electrical signal that is inputted into an electronics package (39) that amplifies the electrical signal and forwards the electrical signal to the transmitter (41) that transforms the electrical signal to an acoustic output signal that is acoustically transmitted.

Abstract: An electromagnetic downlink and pickup apparatus for transmitting and receiving electromagnetic signals is disclosed. The electromagnetic downlink and pickup apparatus includes a subsea conductor (47) disposed beneath the sea floor (16) and a surface installation (58) for generating and interpreting signals. The subsea conductor (47) and the surface installation (58) are electrically connecting by first and second conduits (30, 51) that form a pair terminals on the subsea conductor (47) between which a voltage potential may be established, thereby providing a path for current flow therebetween.

Abstract: An apparatus for obtaining resistivity readings of the earth surrounding a wellbore (32) to determine the downhole location of the apparatus or to generate a log is disclosed. The apparatus comprises an electromagnetic transmitter (40) for transmitting electromagnetic waves (42, 46) into the earth and an electronics package (122). The electronics package includes a power source (200) providing a current to the electromagnetic transmitter (40), a current sensing device (204) for detecting the current drawn by the electromagnetic transmitter (40), a sample and hold circuit (210) for sampling the current drawn by the electromagnetic transmitter (40) and a memory device (214) for storing the current draw information.

Abstract: An electrically insulating gap subassembly for inclusion in a pipe string (30) comprising a pair of tubular members (90, 98) having an electrically insulating isolation subassembly (94) threadably disposed therebetween is disclosed. The electrically insulating isolation subassembly (94) has an anodized aluminum surface that provides electrical isolation to interrupt electrical contact between the two tubular members (90, 98) such that electromagnetic waves (46, 54) carrying information may be generated thereacross.

Abstract: An adjacent well telemetry system for changing the operational state of a downhole device and a method for use of the system is disclosed. The system comprises an electromagnetic transmitter disposed in a wellbore that transmits an command signal that is received by an electromagnetic receiver disposed in an adjacent wellbore. The electromagnetic receiver sends the command signal to an electronics package that generates a driver signal in response to the command signal that prompts the downhole device to change operational states.

Abstract: An apparatus, method and system for communicating information between downhole equipment (40) and surface equipment is disclosed. The electromagnetic signal repeater apparatus (34, 36) comprises a housing (102) that is securably mountable to the exterior of a pipe string (30) disposed in a wellbore (32). The housing (102) includes first and second housing subassemblies (104, 106). The first housing subassembly (104) is electrically isolated from the second housing subassembly (106) by a gap subassembly (108) having a length that is at least two times the diameter of the housing (102). The first housing subassembly (104) is electrically isolated from the pipe string (30) and is secured thereto with a nonconductive strap (120). The second housing subassembly (106) is electrically coupled with the pipe string (30) and is secured thereto with a conductive strap (122). An electronics package (127) and a battery (126) are disposed within the housing (102).

Abstract: A well tool and method are provided for evaluating a subterranean formation through an exposed formation surface, such as the wall of a newly drilled well bore. The tool has a tubular main housing that is connectable into a well work string. A probe and a scraper are extendible from the main housing in response to a first signal of a signal set transmitted from the surface. The probe and the scraper are returnable to the main housing in response to a second signal set transmitted from the surface. The probe provides an isolated fluid conduit from the formation surface to a sensor for measuring a condition in the well. The scraper is for removing debris and for smoothing the formation surface, thereby helping to establish a sealed engagement of the probe to the formation surface. The tool can also be provided with a sampling vessel for taking samples of formation fluids obtained via the isolated fluid conduit in the probe.

Abstract: An apparatus, method and system for communicating information between downhole equipment (40) and surface equipment is disclosed. The electromagnetic signal repeater apparatus (34, 36) comprises a housing (102) that is securably mountable to the exterior of a pipe string (30) disposed in a wellbore (32). The housing (102) includes first and second housing subassemblies (104, 106). The first housing subassembly (104) is electrically isolated from the second housing subassembly (106) by a gap subassembly (108) having a length that is at least two times the diameter of the housing (102). The first housing subassembly (104) is electrically isolated from the pipe string (30) and is secured thereto with a nonconductive strap (120). The second housing subassembly (106) is electrically coupled with the pipe string (30) and is secured thereto with a conductive strap (122). An electronics package (127) and a battery (126) are disposed within the housing (102).

Abstract: A subsea repeater apparatus (48) for communicating information between surface equipment (60) and downhole equipment (44) is disclosed. The apparatus (48) comprises an electromagnetic receiver (66, 68) that receives an electromagnetic signal (46) carrying information from downhole equipment (44) and an acoustic modem (54) that acoustically retransmits (56) the information to surface equipment (60) through the sea. The apparatus (48) may also comprise an acoustic modem (54) that receives an acoustic signal (64) carrying information from surface equipment (60) through the sea and an electromagnetic transmitter (50) that radiates electromagnetic waves (66) carrying the information into the earth.

Abstract: An electromagnetic pickup device (64) for receiving electromagnetic signals (62) is disclosed that comprises an H-field probe (68) having an end (78) the is insertable into the earth (16) for receiving the H-field component of the electromagnetic signal (62) and a plurality of E-field probes (66) that are radially disposed about the H-field probe (68) and electrically isolated from the H-field probe (68), each having an end (76) that is insertable into the earth (16) for receiving the E-field component of the electromagnetic signal (62).

Abstract: A downhole electromagnetic signal repeater (76) for communicating information between surface equipment and downhole equipment and a method for use of the repeater (76) is disclosed. The repeater (76) comprises a receiver (120) and a transmitter (124). The receiver (120) receives an electromagnetic input signal and transforms the electromagnetic input signal to an electrical signal that is inputted into an electronics package (122) that amplifies the electrical signal and forwards the electrical signal to the transmitter (124) that transforms the electrical signal to an electromagnetic output signal that is radiated into the earth.