Abstract: A pressure compensation device for a downhole fluid pressure pulse generator comprising: a membrane sleeve; a membrane support with a bore for receiving a drive-shaft, a central section which receives the membrane sleeve, a male mating section on each side, each having a groove extending around an external surface and at least one opening aligned with the groove; a pair of female mating components with a bore and a channel in an internal surface, each female mating component configured to mate with one of the male mating sections to axially clamp the membrane sleeve between the membrane support and the female mating components; and a pair of retaining rings each received between the male mating section groove and the female mating component channel, where the retaining rings are accessible through the opening in the male mating section and radially expandable into a space in the female mating component to unseat the retaining ring from the groove for removal.

Abstract: A method for determining a rotational position of a rotor in a fluid pressure pulse generator of a downhole telemetry tool comprises: for at least one rotational position of the rotor, determining an expected pressure of a drilling fluid at the fluid pressure pulse generator that corresponds to the at least one rotational position; forming a rotor position map of rotor rotational positions and corresponding expected drilling fluid pressures from the at least one rotational position of the rotor and the corresponding determined expected pressure; measuring a pressure of the drilling fluid at the fluid pressure pulse generator, and determining the rotational position of the rotor at the measured pressure by associating the measured pressure to an expected pressure and corresponding rotor rotational position in the rotor position map.

Abstract: Disclosed are downhole probes in which electrical interconnections between different modules are achieved without wiring harnesses. Modules may be coupled to one another and/or to bulkheads in the probe my couplings that provide substantially rigid couplings. The couplings may be configured to connect together only in one orientation. Electrical connectors may be fixed relative to components of the couplings so that the electrical connectors are automatically aligned for connection by the couplings.

Abstract: A fluid pressure pulse generator for a downhole telemetry tool comprising a stator and a rotor. The stator comprises a stator body and a plurality of radially extending stator projections spaced around the stator body, whereby adjacently spaced stator projections define stator flow channels extending therebetween. The rotor comprises a rotor body and a plurality of radially extending rotor projections spaced around the rotor body. The rotor projections are axially adjacent to the stator projections and the rotor is rotatable relative to the stator such that the rotor projections move in and out of fluid communication with the stator flow channels to create fluid pressure pulses in fluid flowing through the stator flow channels. The rotor projections may be positioned downhole of the stator projections and include a self-correction mechanism to move the rotor to an open flow position where the rotor projections are out of fluid communication with the stator flow channels if the telemetry tool fails.

Abstract: A method and apparatus for downhole data transmission. The method comprising monitoring electrical impedance properties of a downhole formation by applying an electrical signal between a first portion and a second portion of a drill string that are electrically insulated from each other by an insulating portion, selecting a frequency for transmitting data by electromagnetic telemetry based at least in part on the monitored electrical impedance and transmitting the data by encoding the data in a waveform having the selected frequency and applying the waveform between the first portion and the second portion of the drill string.

Abstract: A downhole probe is adapted to be supported in drill string sections having different internal diameters with the use of a set of interchangeable centralizers. Each centralizer is dimensioned to snugly receive the downhole probe and to bear against the bore wall of a drill-string section. Interchangeable axial supports such as spiders may also be provided in a set. The downhole probe may comprise a slick body. As drilling progresses the downhole probe may be adapted to be received in drill string sections of varying diameters.

Abstract: An assembly for use in subsurface drilling includes a downhole probe supported by a locking mechanism with a bore of a drill string section. The probe comprises a first spider and a second spider at the uphole and downhole sections of the probe. The locking mechanism secures the probes in the bore against axial and rotational movement relative the drill string section.

Abstract: A fluid pressure pulse generator for a downhole telemetry tool comprising a stator and a rotor. The stator has a stator body and a plurality of radially extending stator projections spaced around the stator body, with adjacently spaced stator projections defining stator flow channels extending therebetween. The rotor has a rotor body and a plurality of radially extending rotor projections spaced around the rotor body, with adjacently spaced rotor projections defining rotor flow channels extending therebetween. The rotor projections are axially adjacent the stator projections. The rotor is rotatable relative to the stator and is configured to oscillate from an open flow position an equal span of clockwise and counter clockwise rotation to first and second restricted flow positions.

Abstract: Adjustment of the angle of a bent sub or other steering feature in a drill string relative to a reference angle of a downhole sensor is facilitated by a rotatable coupling between the bent sub and the sensor. The rotatable coupling may be rotated to align the high side with a reference indicium and locked at the set angle. Rows of ceramic balls retained in circumferential channels may be provided to permit rotation while carrying tensile and compressional forces. Calibration of the sensor is facilitated and opportunities for certain measurement errors are eliminated. An embodiment provides a mechanism for locking the rotatable coupling at a desired angle. The embodiment comprises a ring with teeth that engage a downhole portion of the coupling and depressions that engage an uphole portion of the coupling.

Abstract: A flow bypass sleeve for a fluid pressure pulse generator of a downhole telemetry tool. The fluid pressure pulse generator comprising a stator having one or more flow channels or orifices through which drilling fluid flows and a rotor which rotates relative to the stator to move in and out of fluid communication with the flow channels or orifices to create fluid pressure pulses in the drilling fluid flowing through the fluid pressure pulse generator. The flow bypass sleeve is configured to attach to a drill collar which housing the telemetry tool and comprises a body with a bore therethrough which receives the fluid pressure pulse generator. The body includes at least one longitudinally extending bypass channel comprising a groove longitudinally extending along an internal surface of the body or an aperture longitudinally extending through the body.

Abstract: A pressure measurement apparatus for a downhole measurement-while-drilling tool comprises a feed through connector and a pressure transducer. The feed through connector comprises a body with opposing first and second ends, at least one electrical interconnection extending axially through the body and out of both ends, and a pressure transducer receptacle in the first end and a communications bore extending from the receptacle to the second end. The pressure transducer is seated in the receptacle such that a pressure at the first end can be measured, and comprises at least one electrical contact that extends from the pressure transducer through the communication bore and out of the second end. The pressure transducer can take pressure measurements for predicting wear of a primary seal in a motor subassembly of the tool, detect a pressure-related battery failure event, and control operation of a dual pulse height fluid pressure pulse generator.

Abstract: A fluid pressure pulse generator comprising a stator and rotor that can be used in measurement while drilling using mud pulse or pressure pulse telemetry is disclosed. The stator comprises a stator body with a circular opening therethrough and the rotor comprises a circular rotor body rotatably received in the circular opening of the stator body. One of the stator body or the rotor body comprises one or more than one fluid opening for flow of fluid therethrough and the other of the stator body or the rotor body comprises one or more than one full flow chamber. The rotor is rotatable between a full flow configuration whereby the full flow chamber and the fluid opening align so that fluid flows from the full flow chamber through the fluid opening, and a reduced flow configuration whereby the full flow chamber and the fluid opening are not aligned.

Abstract: A pressure measurement apparatus for a downhole measurement-while-drilling tool comprises a feed through connector and a pressure transducer. The feed through connector comprises a body with a first end and an opposite second end, at least one electrical interconnection extending axially through the body and out of the first and second ends, and a pressure transducer receptacle in the first end and a communications bore extending from the receptacle to the second end. The pressure transducer is seated in the receptacle such that a pressure at the first end can be measured, and comprises at least one electrical contact that extends from the pressure transducer through the communication bore and out of the second end. The pressure transducer can take pressure measurements used to predict wear of a primary seal in a motor subassembly of the tool, detect a pressure-related battery failure event, and control operation of a dual pulse height fluid pressure pulse generator.

Abstract: A method and apparatus for downhole data transmission. The method comprising monitoring electrical impedance properties of a downhole formation by applying an electrical signal between a first portion and a second portion of a drill string that are electrically insulated from each other by an insulating portion, selecting a frequency for transmitting data by electromagnetic telemetry based at least in part on the monitored electrical impedance and transmitting the data by encoding the data in a waveform having the selected frequency and applying the waveform between the first portion and the second portion of the drill string.

Abstract: A method for selecting a drilling fluid pressure pulse transmission frequency in a downhole telemetry tool comprises: emitting a frequency sweep wave in a drilling fluid that comprises pressure pulses over a range of frequencies and over a period of time; measuring a pressure of the drilling fluid at the telemetry tool while the frequency sweep wave is being emitted; determining a signal strength at each frequency in the range of frequencies from the measured pressure of the drilling fluid; and selecting at least one frequency in the range of frequencies that meets a selected signal strength threshold as a telemetry signal transmission frequency for the telemetry tool.

Abstract: A fluid pressure pulse generator for a downhole telemetry tool comprising a stator and a rotor. The stator comprises a stator flow diverter radially extending across a flow path for fluid flowing through the fluid pressure pulse generator and having one or more than one stator flow channel therethrough through which the fluid flows. The rotor comprises a rotor flow diverter radially extending across the flow path for fluid flowing through the fluid pressure pulse generator and having one or more than one rotor flow channel therethrough through which the fluid flows. The rotor flow diverter is axially adjacent the stator flow diverter and the rotor flow diverter is rotatable relative to the stator flow diverter to move the one or more than one rotor flow channel in and out of fluid communication with the one or more than one stator flow channel to create fluid pressure pulses in the fluid flowing through the fluid pressure pulse generator.

Abstract: An electromagnetic telemetry signal generating assembly comprises a first section of drill string, a second section of drill string, a gap sub configured to insulate the first section from the second section, and a power source configured to provide a first voltage to a control circuit. The control circuit is configured to drive a second voltage between the sections of drill string. The gap sub provides a gap of at least 12 inches (30 cm). The second voltage may be different than the first voltage.

Abstract: A flow bypass sleeve for a fluid pressure pulse generator of a downhole telemetry tool. The fluid pressure pulse generator comprising a stator having one or more flow channels or orifices through which drilling fluid flows and a rotor which rotates relative to the stator to move in and out of fluid communication with the flow channels or orifices to create fluid pressure pulses in the drilling fluid flowing through the fluid pressure pulse generator. The flow bypass sleeve is configured to attach to a drill collar which housing the telemetry tool and comprises a body with a bore therethrough which receives the fluid pressure pulse generator. The body includes at least one longitudinally extending bypass channel comprising a groove longitudinally extending along an internal surface of the body or an aperture longitudinally extending through the body.

Abstract: A telemetry system with a plurality of controllers and telemetry systems, where the controllers are configured to obtain information from one or more sensors and transmit that information on one or more of the plurality of telemetry systems. The configuration of a controller may be changed so as to change which information is transmitted on a given telemetry system.

Abstract: A telemetry system with a plurality of controllers and telemetry systems, where the controllers are configured to obtain information from one or more sensors and transmit that information on one or more of the plurality of telemetry systems. The configuration of a controller may be changed so as to change which information is transmitted on a given telemetry system.