Abstract: An apparatus can include a choke with a flow restrictor having at least two positions, a flow coefficient Cv of the choke with the flow restrictor in one position being less than with the flow restrictor in the other position, and an operational device that displaces the flow restrictor at a variable actuation rate, the actuation rate with the flow restrictor in one position being less than with the flow restrictor in the other position. A method can include displacing a flow restrictor, thereby decreasing a flow coefficient Cv of a choke, and decreasing a rate of change of the flow coefficient Cv in response to decreasing the flow coefficient Cv. A drilling system can include a choke with a flow restrictor, and a continuously variable transmission which causes an actuation rate to vary based on a position of the flow restrictor.

Abstract: A flow measurement apparatus can include a main flow passage, a variable flow restrictor, a bypass flow passage having an inlet connected with the main flow passage upstream of the variable flow restrictor and an outlet connected with the main flow passage downstream of the variable flow restrictor, and a mass flowmeter connected in the bypass flow passage between the inlet and the outlet. A method can include connecting a flow measurement apparatus, so that a fluid flow in a well also flows through the flow measurement apparatus, and varying a restriction to the fluid flow through the variable flow restrictor in response to a change in a flow rate of the fluid flow.

Abstract: A flow measurement apparatus can include a main flow passage, a variable flow restrictor, a bypass flow passage having an inlet connected with the main flow passage upstream of the variable flow restrictor and an outlet connected with the main flow passage downstream of the variable flow restrictor, and a mass flowmeter connected in the bypass flow passage between the inlet and the outlet. A method can include connecting a flow measurement apparatus, so that a fluid flow in a well also flows through the flow measurement apparatus, and varying a restriction to the fluid flow through the variable flow restrictor in response to a change in a flow rate of the fluid flow.

Abstract: An apparatus can include a choke with a flow restrictor member having at least two positions, a flow coefficient Cv of the choke with the flow restrictor member in one position being less than with the flow restrictor member in the other position, and an operational device that displaces the flow restrictor member at a variable actuation rate, the actuation rate with the flow restrictor member in one position being less than with the flow restrictor in the other position. A method can include displacing a flow restrictor member, thereby decreasing a flow coefficient Cv of a choke, and decreasing a rate of change of the flow coefficient Cv in response to decreasing the flow coefficient Cv. A drilling system can include a choke with a flow restrictor member, and a continuously variable transmission which causes an actuation rate to vary based on a position of the flow restrictor member.

Abstract: A drilling choke is controlled in a controlled pressure system. Pressure and position of the drilling choke are monitored. An adjustment to the position of the choke is determined based on the monitored pressure to control the drilling pressures. An actuation is produced of an actuator operably coupled to the choke to implement the determined adjustment. Rather than directly transferring, the actuation of the actuator is transferred with a transfer mechanism to motion of the choke in a non-linear relationship relative to the position of the choke. Generally, motion of the choke's internal trim (e.g., gate, ball, flapper, disc, etc.) is made quicker when near a fully opened position and is made slower when near a fully closed position. This reduces the need for strict precision for the motion. In the end, the monitored pressure is altered in response to the implemented choke adjustment.

Abstract: In a drilling system for drilling a borehole with drilling fluid, a flow loop communicates the drilling fluid, and a differential pressure device in the flow loop at a measurement location produces a pressure drop in flow. The measurement location can be between the borehole and a drilling choke or between a mud pump and the borehole. Piping diverts a portion of the flow at the measurement location so a flowmeter can measure the diverted flow portion. A processing unit receives a measured parameter from the flowmeter and determines a diverted flow rate of the diverted portion therefrom to correlate it to a value of the main flow rate through the flow loop at the measurement location.

Abstract: In a drilling system for drilling a borehole with drilling fluid, a flow loop communicates the drilling fluid, and a differential pressure device in the flow loop at a measurement location produces a pressure drop in flow. The measurement location can be between the borehole and a drilling choke or between a mud pump and the borehole. Piping diverts a portion of the flow at the measurement location so a flowmeter can measure the diverted flow portion. A processing unit receives a measured parameter from the flowmeter and determines a diverted flow rate of the diverted portion therefrom to correlate it to a value of the main flow rate through the flow loop at the measurement location.

Abstract: A drilling system used with drilling fluid for drilling a wellbore has at least one choke in adjustable communication with flow from the wellbore. A programmable control device determines a flow coefficient value of the choke from a measured position value and a stored characteristic of the choke. The device then calculates a first value of the flow of the drilling fluid from the wellbore through the choke based on the flow coefficient value and a pressure differential measured across the choke. The device adjusts operation of the drilling system at least partially based on the calculated flow value. To adjust operation, the device can set the choke (or another choke) to a set flow value relative to the calculated first flow value. Density of the flow can also be determined so the device can adjust operation based on mass flow rate.

Abstract: An assembly is used with a remote source of hydraulic power to control flow of wellbore fluid in a drilling system. At least one choke is operable to control the flow of the fluid to other portions of the system. At least one hydraulic actuator disposed with the choke actuates operation of the choke in response to the hydraulic power. At least one control valve disposed with the choke controls supply of the hydraulic power to and controls return of the hydraulic power from the actuator. An accumulator can be disposed with the choke and coupled to the supply upstream of the control valve. The control valve can couple to the actuator with a pair of pilot-operated check valves disposed in fluid communication between the control valve and the actuator. A stage tank and stage pump can be disposed with the choke. The tank receives the return from the control valve, and the stage pump can pump the return from the stage tank to the source.

Abstract: An assembly uses a choke to control flow of wellbore fluid in a drilling system. A controller operatively coupled to the choke can control opening/closing of the choke with hydraulic power and an actuator. The control operates the opening/closing of the choke with a choke control value to control a parameter in the drilling system, such as pressure or flow. The control measure a time for the choke to at least reach a position toward a full open/closed position during a full opening/closing operation and calculates a current opening/closing speed of the choke. When this current speed is compared to a previously stored speed, the control adjusts the choke control value for the choke based on any difference.

Abstract: A drilling system for drilling a wellbore has one or more valves or chokes to control the upstream pressure of drilling fluid flow in a controlled pressure drilling operation. A measurement is obtained of the drilling fluid flow from the wellbore. Based on the obtained measurement, the drilling fluid flow is selectively distributed with a distributor through one or more of a plurality of flowmeters, such as Coriolis meters. A reading of the drilling fluid flow is obtained from the selected flowmeter(s). Upstream pressure in the drilling fluid flow is controlled with the one or more valve based at least in part on the reading from the one or more selected flowmeters. The reading can be a flow rate, a pressure, or the like compared to capacities of the flowmeters. Additional valves downstream of the flowmeters can be controlled based on cavitation that the valves are estimated to produce.

Abstract: A Coriolis flow meter for a drilling system measures flow from a wellbore and/or from at least one pump into the wellbore. The meter can be disposed upstream of at least one choke used for controlling backpressure, and/or the meter can be disposed between at least one pump and the wellbore. The meter has at least one flow tube adapted to vibrate and conducts the flow at a first pressure level from an inlet side to an outlet side. A vessel encloses the at least one flow tube at least between the inlet and outlet sides and holds a second pressure level therein about the at least one flow tube. The second pressure level can be equal to or nearly equal to the first pressure level to reduce or nearly eliminate a pressure differential across the at least one flow tube. For example, the second pressure level can be elevated above environmental relative to the first pressure level to reduce a pressure differential across the at least one flow tube.

Abstract: A drilling choke is controlled in a controlled pressure system. Pressure is monitored in the controlled pressure system, and position of the drilling choke is monitored. An adjustment to the position of the drilling choke is determined based on the monitored pressure to control the drilling pressures. An actuation is produced of an actuator operably coupled to the drilling choke to implement the determined adjustment. Rather than directly transferring, the actuation of the actuator is transferred with a transfer mechanism to motion of the drilling in a non-linear relationship relative to the position of the drilling choke. Generally, motion of the choke's internal trim (e.g., gate, ball, flapper, disc, etc.) is made quicker when near a fully opened position and is made slower when near a fully closed position. This reduces the need for strict precision for the motion. In the end, the monitored pressure is altered in response to the implemented adjustment of the drilling choke.

Abstract: A drilling system used with drilling fluid for drilling a wellbore has at least one choke in adjustable communication with flow from the wellbore. A programmable control device determines a flow coefficient value of the choke from a measured position value and a stored characteristic of the choke. The device then calculates a first value of the flow of the drilling fluid from the wellbore through the choke based on the flow coefficient value and a pressure differential measured across the choke. The device adjusts operation of the drilling system at least partially based on the calculated flow value. To adjust operation, the device can set the choke (or another choke) to a set flow value relative to the calculated first flow value. Density of the flow can also be determined so the device can adjust operation based on mass flow rate.

Abstract: An assembly uses a choke to control flow of wellbore fluid in a drilling system. A controller operatively coupled to the choke can control opening/closing of the choke with hydraulic power and an actuator. The control operates the opening/closing of the choke with a choke control value to control a parameter in the drilling system, such as pressure or flow. The control measure a time for the choke to at least reach a position toward a full open/closed position during a full opening/closing operation and calculates a current opening/closing speed of the choke. When this current speed is compared to a previously stored speed, the control adjusts the choke control value for the choke based on any difference.

Abstract: An assembly is used with a remote source of hydraulic power to control flow of wellbore fluid in a drilling system. At least one choke is operable to control the flow of the fluid to other portions of the system. At least one hydraulic actuator disposed with the choke actuates operation of the choke in response to the hydraulic power. At least one control valve disposed with the choke controls supply of the hydraulic power to and controls return of the hydraulic power from the actuator. An accumulator can be disposed with the choke and coupled to the supply upstream of the control valve. The control valve can couple to the actuator with a pair of pilot-operated check valves disposed in fluid communication between the control valve and the actuator. A stage tank and stage pump can be disposed with the choke. The tank receives the return from the control valve, and the stage pump can pump the return from the stage tank to the source.

Abstract: A drilling system for drilling a wellbore has one or more valves or chokes to control the upstream pressure of drilling fluid flow in a controlled pressure drilling operation. A measurement is obtained of the drilling fluid flow from the wellbore. Based on the obtained measurement, the drilling fluid flow is selectively distributed with a distributor through one or more of a plurality of flowmeters, such as Coriolis meters. A reading of the drilling fluid flow is obtained from the selected flowmeter(s). Upstream pressure in the drilling fluid flow is controlled with the one or more valve based at least in part on the reading from the one or more selected flowmeters. The reading can be a flow rate, a pressure, or the like compared to capacities of the flowmeters. Additional valves downstream of the flowmeters can be controlled based on cavitation that the valves are estimated to produce.

Abstract: A Coriolis flow meter for a drilling system measures flow from a wellbore and/or from at least one pump into the wellbore. The meter can be disposed upstream of at least one choke used for controlling backpressure, and/or the meter can be disposed between at least one pump and the wellbore. The meter has at least one flow tube adapted to vibrate and conducts the flow at a first pressure level from an inlet side to an outlet side. A vessel encloses the at least one flow tube at least between the inlet and outlet sides and holds a second pressure level therein about the at least one flow tube. The second pressure level can be equal to or nearly equal to the first pressure level to reduce or nearly eliminate a pressure differential across the at least one flow tube. For example, the second pressure level can be elevated above environmental relative to the first pressure level to reduce a pressure differential across the at least one flow tube.

Abstract: A rolling cutter drill bit and method for making a rolling cutter drill bit having a cutting insert pressed into a socket, wherein the socket forms a juncture with the curved outer surface of a rolling cutter, and the juncture contacts a plane in contact with the juncture in at least three points located on the juncture.