Abstract: An apparatus for creating pressure pulses in the fluid of a bore hole is described. The preferred embodiment takes the form of a mud pulser apparatus having a signalling valve controlled by a variable pilot valve. The forces on the signalling valve are balanced and controlled by the flow of mud through the variable orifice of the pilot valve. The arrangement is such as to act like a hydraulic amplifier, and results in the signalling valve being compensated for variable flow rates. In the preferred embodiment, the pilot valve has rotary vanes that allow it to be self-cleaning.

Abstract: A rotary steerable tool (2) for use in a downhole drilling apparatus for adjusting the direction of drilling is disclosed. The tool comprises a tubular outer housing (20) and a row of steering pushers (24) slidably mounted to the housing for movement between an extended position, in which the steering pusher engages a wall of a borehole formed by the drilling apparatus, and a withdrawn position, in which the steering pushers do not engage the wall of the borehole. A tubular sleeve (4) is mounted inside the housing (20) to transmit rotary drive to a drilling bit. A pressure chamber (22) defined between the sleeve (4) and the housing (20) communicates with the steering pushers (24) to move the steering pushers (24) to the extended position.

Abstract: A direction adjustment tool for a downhole drilling apparatus is disclosed. The tool has a tubular housing adapted to be incorporated into a downhole drilling apparatus, and steering blades mounted to the housing. A drive shaft transmits drive to a drill bit of a drilling apparatus, wherein the shaft defines a passage for transmitting drilling fluid to the drill bit. A first pressure chamber is defined between the housing and the shaft and communicates with the passage, wherein the steering blades are moved from retracted positions to extended positions thereof as a result of increase of fluid pressure the first pressure chamber. A pendulum member is pivotably mounted to extend in a vertical orientation when the shaft is not rotating relative to the housing, and pistons prevent movement of at least one steering blade to the extended position thereof as a result of the angle between a longitudinal axis of the shaft and the longitudinal axis of the pendulum member exceeding a predetermined amount.

Abstract: A downhole drilling apparatus incorporating an orientation sensor (24) is disclosed. The orientation sensor is mounted to a housing (16) for providing a signal representing the orientation of the housing, and is connected to a first transceiver coil (26). A second transceiver coil (30) and a series of magnets (32) are mounted to a rotary shaft (18). As the shaft rotates relative to the housing, passage of the magnets past the first transceiver coil generates a voltage to provide electrical power to the sensor, and electromagnetic coupling between the first and second transceiver coils enables signals from the sensor to be transmitted to a measurement while drilling tool mounted on the rotary shaft.

Abstract: A direction adjustment tool 2 for a downhole drilling apparatus is disclosed. The tool has a tubular housing 8 adapted to be incorporated into a downhole drilling apparatus, and steering blades 10 mounted to the housing. A drive shaft 16 transmits drive to a drill bit of a drilling apparatus, wherein the shaft defines a passage for transmitting drilling fluid to the drill bit. A first pressure chamber 32 is defined between the housing and the shaft and communicates with the passage, wherein the steering blades are moved from retracted positions to extended positions thereof as a result of increase of fluid pressure the first pressure chamber.

Abstract: An apparatus for creating pressure pulses in the fluid of a bore hole is described. The preferred embodiment takes the form of a mud pulser apparatus (10) having a signalling valve controlled by a variable pilot valve (34). The forces on the signalling valve are balanced and controlled by the flow of mud through the variable orifice of the pilot valve. The arrangement is such as to act like a hydraulic amplifier, and results in the signalling valve being compensated for variable flow rates. In the preferred embodiment, the pilot valve has rotary vanes that allow it to be self-cleaning.

Abstract: A rotary steerable tool for use in a downhole drilling apparatus for adjusting the direction of drilling is disclosed. The tool comprises a tubular outer housing and a row of steering pushers slidably mounted to the housing for movement between an extended position, in which the steering pusher engages a wall of a borehole formed by the drilling apparatus, and a withdrawn position, in which the steering pushers do not engage the wall of the borehole. A tubular sleeve is mounted inside the housing to transmit rotary drive to a drilling bit. A pressure chamber defined between the sleeve and the housing communicates with the steering pushers to move the steering pushers to the extended position.