A downhole actuator typically for a downhole tool such as a valve, and typically for incorporation in a string of tubulars in an oil or gas well has a central axis with radially movable counterweights on opposite sides of the axis, which move radially outward to change the activation state of the actuator. The counterweights are supported by link arms which control the movement of the counterweights in response to centrifugal force created by rotation of the body, for example, during rotary drilling operations of the string. Radial outward movement of the counterweights typically transmits axial forces between sleeves at the upper and lower ends of the counterweights, so when the counterweights move radially outward, the upper and lower sleeves approach one another, which typically triggers the actuator.

A jet flow adjustment method for rotary steerable downhole release relates to a technical field of downhole drilling equipment for oil wells, which includes steps of: defining a diversion ratio p of a jet nozzle (2) by a ground control system according to a cleaning requirement of a cuttings bed; and sending the diversion ratio p of the jet nozzle (2) to a control unit of a downhole rotary steerable system; and determining an opening area s of the jet nozzle (2) by the control unit of the downhole rotary steerable system according to the diversion ratio p of the jet nozzle (2) and an equivalent channel area S of a drilling tool, wherein a calculation formula is: s=p*S/(1−p); controlling an adjustable bypass valve (3) by the control unit of the downhole rotary steerable system according to the calculated opening area s of the jet nozzle (2), so as to control an overlapping area between sector holes (9) of a rotor end (7) and a stator end (8), thereby opening the jet nozzle (2) for release. The present invention has simple control and strong release ability, which can effectively solve the jamming problem of the rotary steerable downhole tool.

A rotor catch assembly for connection in a workstring in a wellbore is provided. The rotor catch assembly is connected to a downhole motor assembly that includes a rotor that is driven by a fluid. In the normal operating state of the rotor catch assembly, fluid flows through the catch assembly and causes the rotor to rotate. In this state, the catch assembly generates pressure pulses in the fluid in the workstring to facilitate advancement of the workstring in the wellbore. In the event of a failure of a mechanical connection in the motor assembly, the rotor catch assembly shifts to a catch-activated state in which the motor assembly is disabled.

A rotational continuous circulation system and methods includes a circulation sub having an internal bore extending along a central axis. The circulation sub has an uphole body having a reduced outer diameter along a downhole length of the uphole body. A central valve selectively opens and closes the uphole internal bore. At least one check valve is located within a sidewall of the uphole body to selectively allow fluid to flow into the uphole internal bore through the at least one check valve. A downhole body has an uphole portion circumscribing a downhole portion of the uphole body. A sleeve assembly circumscribes the reduced outer diameter of the uphole body. The uphole body and the downhole body are configured to rotate about the central axis independently from the sleeve assembly. A side-entry port of the sleeve assembly provides a fluid flow path from an exterior of the sleeve assembly to the at least one check valve.

A protection system for a drilling riser. The drilling riser includes a main drilling riser bore and a drilling riser annulus and extends from a floating installation to a location on a seafloor and is fluidly connected to a subsea BOP. The system includes a fluid conduit which extends from the floating installation to a lower region of the drilling riser. The fluid conduit is fluidly connected with the drilling riser annulus in the drilling riser. The fluid conduit provides at least one of a rapid pressure relief and a fluid bypass for the main drilling riser bore to prevent the drilling riser from an uncontrolled pressure build-up due to an inadvertent plugging or a restriction resulting in a maximum allowable working pressure (MAWP) of the drilling riser being exceeded, if a restriction, a plug or a blockage exists in the drilling riser annulus or in riser outlets.

A drilling assembly includes a drill string configured to be disposed within a wellbore. The drilling assembly also includes a sub fluidically coupled to the drill string. The sub includes a mandrel fixed to the drill string and defines an external helically undulated surface and a bore configured to flow drilling fluid received from the drill string. The sub includes a sleeve rotationally coupled to and disposed outside the mandrel. The sleeve has an internal helically undulated surface corresponding with the external helically undulated surface of the mandrel to form, with the mandrel, a progressive cavity. The progressive cavity receives fluid from the bore of the mandrel to rotate the sleeve as the drilling fluid flows along the cavity. The sub also includes a valve configured to regulate a flow of the drilling fluid along the bore to direct fluid toward or away from the progressive cavity.

This invention relates to an apparatus and method for controlling a part of a downhole assembly, and to the downhole assembly. The downhole assembly may include a steering mechanism adapted to steer a drill bit in a chosen direction, and the steering mechanism may be the part of the downhole assembly which is controlled by the apparatus. The downhole assembly includes a drill bit and a motor, the motor having a stator and a rotor, the rotor being driven to rotate relative to the stator by the passage of a drilling fluid along a drilling fluid path between the rotor and the stator. The motor has a conduit through which the drilling fluid can pass, the conduit being separate from the drilling fluid path, and the apparatus has a valve to control the flow of drilling fluid through the conduit. The invention provides a robust and reliable means of delivering high pressure drilling fluid downstream of the motor.

A flow diverter is provided having a first sub member, a second sub member, a third sub member connected in series and a piston, a spring, and a sleeve member. The sleeve member is removeably disposed within the second sub member. The spring concentrically surrounds at least a portion of the piston and the spring are slidably disposed within the first sub member with the piston further slidably disposed within the second sub member and at least a portion of the third sub member. A drilling fluid having a first predetermined pressure passes through the flow diverter. The drilling fluid having a second predetermined pressure moves the piston until at least a portion of the drilling fluid passes through bypass ports formed in the piston, sleeve member, and second sub member and out of the flow diverter, thus controlling the pressure of the drilling fluid.

A method and apparatus that includes an elongated base pipe having an external surface at least partially defining an external region and an internal surface at least partially defining an internal region; and a pressure maintenance device disposed in the base pipe and comprising: a flow path that extends between the internal region and the external region; and a valve having a gas charged chamber, the valve allowing the flow of a fluid from the internal region to the external region through the first flow path when a pressure differential between a pressure associated with the internal region and a pressure associated with the gas charged chamber is less than a maximum pressure threshold and when a pressure differential between the external region and the pressure associated with the gas charged chamber is greater than a minimum pressure threshold.

A method for operating a circulating sub in a well includes opening a port of the circulating sub, including: dropping a ball into a drill pipe containing a downhole fluid; and seating the ball on an actuator slidably disposed concentrically within the drill pipe, in which seating the ball on the actuator causes motion of the actuator relative to the drill pipe to open a port defined in a wall of the drill pipe. The method includes closing the port of the circulating sub, including: introducing a solvent different from the downhole fluid into the drill pipe, in which a solubility of the ball in the solvent is greater than a solubility of the ball in the downhole fluid; and degrading the ball in the solvent, in which the degrading of the ball causes motion of the actuator relative to the drill pipe to close the port.