Abstract: A gap sub has electrically-conductive parts held together by electrical insulators which engage in channels formed in the parts. The electrical insulators hold the parts in a spaced-apart electrically-insulated relationship. In some embodiments, the electrical insulators are removable to allow separation of the parts. An insulating oil or other fluid may fill the gap.

Abstract: An assembly for use in subsurface drilling includes a downhole downhole probe supported by a centralizer. The centralizer comprises a tubular member that extends around the downhole probe. A wall of the centralizer is fluted to provide inward contact points that support the downhole probe and outward contact points that bear against a bore wall of a section of drill string. The downhole probe may be supported for substantially its entire length.

Abstract: The embodiments described herein generally relate to a fluid pressure pulse generating apparatus with a primary seal assembly, back up seal assembly and pressure compensation device. The pressure compensation device comprises a membrane support and a longitudinally extending membrane system. The membrane support has a longitudinally extending bore therethrough for receiving a driveshaft of the fluid pressure pulse generating apparatus. The longitudinally extending membrane system comprising a longitudinally extending outer membrane sleeve and a longitudinally extending inner membrane sleeve with the inner membrane sleeve positioned inside the outer membrane sleeve. The membrane system is sealed to the membrane support to allow flexing of the membrane system in response to fluid pressure on either an inner longitudinal surface of the membrane system or an outer longitudinal surface of the membrane system and to prevent fluid on the inner longitudinal surface mixing with fluid on the outer longitudinal surface.

Abstract: An assembly for use in subsurface drilling includes a downhole probe supported by a centralizer. The centralizer comprises a tubular member that extends around the downhole probe. A wall of the centralizer is fluted to provide inward contact points that support the downhole probe and outward contact points that bear against a bore wall of a section of drill string. The downhole probe may be supported for substantially its entire length.

Abstract: A downhole apparatus for measuring drilling fluid characteristics. The downhole apparatus may comprise one or more sensors located within a housing. The sensors may include one or more of an imaging device, a resistivity/conductivity sensor, a temperature sensor, a pressure sensor, a flowmeter and a fluid density sensor. The downhole apparatus may also include a controller for receiving measurements and/or determining optimal electromagnetic telemetry transmission settings. The downhole apparatus may also comprise a transmitter for transmitting the measurements and/or the optimal electromagnetic transmission settings. The downhole apparatus may be operated to determine optimal transmission settings for an electromagnetic telemetry system. Optimal transmission settings may include settings relating to one or more of frequency, amplitude, voltage, current, and power.

Abstract: A coupling key for fixedly coupling a driveshaft to a rotating component of a measurement while drilling telemetry apparatus comprises a key body and at least one zero backlash ring. The key body has dimensions selected to fit within a keyhole of a driveshaft and a receptacle of a rotating component, with a gap that is large enough that the key body can be freely inserted into the keyhole and receptacle and small enough that the coupling body can couple the driveshaft to the rotating component in a rotational direction. The least one zero backlash ring extends around the key body and protrudes from surfaces of the key body and into the gap such that an interference fit is established between the coupling key, the keyhole, and the receptacle when the coupling key is coupling the driveshaft and rotating component together.

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: An assembly for use in subsurface drilling includes a downhole probe supported by a centralizer. The centralizer comprises a tubular member that extends around the downhole probe. A wall of the centralizer is fluted to provide inward contact points that support the downhole probe and outward contact points that bear against a bore wall of a section of drill string. The downhole probe may be supported for substantially its entire length.

Abstract: The embodiments described herein generally relate to a fluid pressure pulse generating apparatus with a primary seal assembly, back up seal assembly and pressure compensation device. The pressure compensation device comprises a membrane support and a longitudinally extending membrane system. The membrane support has a longitudinally extending bore therethrough for receiving a drive-shaft of the fluid pressure pulse generating apparatus. The longitudinally extending membrane system comprising a longitudinally extending outer membrane sleeve and a longitudinally extending inner membrane sleeve with the inner membrane sleeve positioned inside the outer membrane sleeve.

Abstract: A fluid pressure pulse generating apparatus with a pulser assembly having a pulser assembly housing enclosing a pressure compensation device. The pulser assembly housing includes an interior wall with a plurality of primary apertures therethrough and an exterior wall with a plurality of secondary apertures therethrough, the exterior wall overlying the interior wall. The primary and secondary apertures are in fluid communication with a pressure compensation mechanism in the pressure compensation device such that drilling fluid contacts the pressure compensation mechanism for equalization of pressure of a lubrication liquid contained inside the pulser assembly housing with pressure of the drilling fluid when the fluid pressure pulse generating apparatus is positioned downhole.

Abstract: A mud hammer is driven by the flow of drilling fluid to generate pressure pulses. Timing and/or amplitude of the pulses are altered to encode data by applying electromagnetic forces to a movable member of the mud hammer. In an example embodiment the movable member carries one or more magnets and electromagnetic forces are applied to the movable member by one or more electromagnets. The mud hammer may also generate electrical power that may be applied to charge batteries and/or drive downhole electrical apparatus.

Abstract: A pulser assembly for a downhole measurement-while-drilling tool comprises a motor subassembly and an electronics subassembly electrically coupled to the motor subassembly. The motor subassembly comprises a motor, a motor subassembly housing that houses the motor, a spectrometer inside the motor subassembly housing and a driveshaft extending from the motor out of the motor subassembly housing for coupling with a rotor of a fluid pressure pulse generator. The spectrometer includes an optical sensor for optical communication with a lubrication liquid when the lubrication liquid is sealed inside the motor subassembly housing. The electronics subassembly comprises electronics equipment and an electronics subassembly housing that houses the electronics equipment. Optical measurements from the spectrometer may be used to determine a molecular composition of the lubrication liquid in the downhole tool.

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: 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: Apparatus for directional drilling allows an uphole section of drill string to be rotated while maintaining a desired orientation of a bent section of the drill string. In some embodiments, clutches above and below the bent section are selectively operated to rotate the bent section to a desired orientation. Reducing transmissions may reduce the rotation rate of the bent section.

Abstract: A mud hammer is driven by the flow of drilling fluid to generate pressure pulses. Timing and/or amplitude of the pulses are altered to encode data by applying electromagnetic forces to a movable member of the mud hammer. In an example embodiment the movable member carries one or more magnets and electromagnetic forces are applied to the movable member by one or more electromagnets. The mud hammer may also generate electrical power that may be applied to charge batteries and/or drive downhole electrical apparatus.

Abstract: A gap sub comprises a female member comprising a first and second plurality of apertures, and a male member comprising a first and second plurality of cavities. A plurality of non-conductive pins may be inserted through the second plurality of apertures and the second plurality of cavities, thereby locking the relative positions of the female and male members. A plurality of conductive pins may be inserted through the first plurality of apertures and the first plurality of cavities such that there are no electrical connections between the conductive pins and the male member. A dielectric material may be inserted between the male member and the conductive pins.

Abstract: A downhole system has a plurality of telemetry systems and a control system 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 and how the information is to be transmitted on the given telemetry system.

Abstract: A fluid pressure pulse generator comprises a stator having a body with a cylindrical bore and a fluid flow chamber comprising a lateral opening and an uphole axial inlet, and a rotor having a cylindrical body rotatably seated within the bore, a rotor head connected to the rotor body, and a fluid diverter comprising a fluid passage through the rotor body and a nozzle in the rotor head. A fluid passage has an opening on an outside surface of the rotor body and an outlet at an end of the rotor body. The nozzle has an inlet end communicable with a drilling fluid and an outlet end in fluid communication with the fluid opening. The flow area of the nozzle increases from the inlet to outlet end such that the velocity of the drilling fluid slows while from inlet to outlet end.

Abstract: A fluid pressure pulse generator comprises a stator having a body and cylindrical bore and a rotor having a cylindrical body and cap. The diameter of the cylindrical body is smaller than that of the stator central bore such that an annular gap is formed therebetween. The cap has a base with a diameter larger than that of the rotor body, forming a protruding lip that covers at least a portion of the annular gap. The stator body and rotor body collectively have at least one fluid flow chamber comprising a lateral opening and an uphole axial inlet, and a downhole axial outlet and at least one fluid diverter comprising a lateral opening in fluid communication with the axial outlet. The rotor can rotate within the stator such that the fluid diverter moves in and out of fluid communication with the fluid flow chamber to create fluid pressure pulses.