Drilling choke with matched actuator

A drilling system comprising a drill string which extends into a wellbore to form an annular space in the wellbore around the drill string, a return fluid flow conduit which is connected to the annular space, and a choke system comprising a choke having an inlet and an outlet, a central flow passage which extends between the inlet and outlet, and a cylindrical plug having a longitudinal cylinder axis, which is rotatable about the longitudinal cylinder axis to vary the degree to which fluid flow along the central flow passage is restricted, the choke system further comprising an actuator which is operable to rotate the plug to vary the degree to which fluid flow along the central flow passage is restricted, the plug being movable between a closed position in which the plug substantially prevents flow of fluid along the central flow passage and an open position in which flow of fluid along the central flow passage is restricted by the plug to a minimum extent, the choke being mounted in the return fluid flow conduit so that the central flow passage forms part of the return fluid flow conduit and fluid returning from the wellbore enters the choke system at the inlet, the plug being provided with a plug passage which has a first end and a second end and which is arranged so that when the plug is in its open position, fluid can pass along the central flow passage of the choke from the inlet to the outlet of the choke via the plug passage from the first end of the second end of the plug passage, wherein the plug is provided with a removable plug insert which surrounds the second end of the plug passage, and further comprising a removable downstream insert and upstream insert which surround and engage with the plug to provide bearing surfaces for rotation of the plug relative to a choke body, the upstream insert engaging with the plug at the inlet side thereof and the downstream insert engaging with the plug at the outlet side thereof, wherein the downstream insert is made from a softer material than the plug insert.

A drilling system comprising a drill string which extends into a wellbore to form an annular space in the wellbore around the drill string, a return fluid flow conduit which is connected to the annular space, and a choke system comprising a choke having an inlet and an outlet, a central flow passage which extends between the inlet and outlet, and a cylindrical plug having a longitudinal cylinder axis, which is rotatable about the longitudinal cylinder axis to vary the degree to which fluid flow along the central flow passage is restricted, the choke system further comprising an actuator which is operable to rotate the plug to vary the degree to which fluid flow along the central flow passage is restricted, the plug being movable between a closed position in which the plug substantially prevents flow of fluid along the central flow passage and an open position in which flow of fluid along the central flow passage is restricted by the plug to a minimum extent, the choke being mounted in the return fluid flow conduit so that the central flow passage forms part of the return fluid flow conduit and fluid returning from the wellbore enters the choke system at the inlet, the plug being provided with a plug passage which has a first end and a second end and which is arranged so that when the plug is in its open position, fluid can pass along the central flow passage of the choke from the inlet to the outlet of the choke via the plug passage from the first end of the second end of the plug passage, wherein the plug is provided with a removable plug insert which surrounds the second end of the plug passage, wherein the choke has a choke body which encloses the central flow passage, the plug being mounted for rotation in the choke body, and a removable bore insert which is mounted in the choke body around the outlet, wherein the choke further comprises a separate removable downstream insert which is mounted in the choke body to engage with the plug at the downstream side thereof, the downstream insert being adjacent the bore insert and between the bore insert and the plug so that the downstream insert and bore insert surround the central flow passage at the outlet side of the plug.