Abstract: A subsurface safety valve actuation system in well tubing comprising a safety valve, piston assembly, motor, pump, spring, reservoir, first valve, and second valve configured to provide pressure in a chamber of the piston assembly that drives the safety valve to an open position, retain pressure in the chamber that retains the safety valve in the open position, release pressure in the chamber via a first hydraulic release path and/or a second hydraulic release path between the chamber and the reservoir that extends through the first valve and second valve, respectively, and the first and second hydraulic release paths being independent from each other, whereby pressure in the chamber that retains the safety valve in the open position may be released via the first or second hydraulic release path when there is a fault in the other of the first or second release path.

Abstract: A subsurface safety valve actuation system in well tubing comprising a safety valve, piston assembly, motor, pump, spring, reservoir, first valve, and second valve configured to provide pressure in a chamber of the piston assembly that drives the safety valve to an open position, retain pressure in the chamber that retains the safety valve in the open position, release pressure in the chamber via a first hydraulic release path and/or a second hydraulic release path between the chamber and the reservoir that extends through the first valve and second valve, respectively, and the first and second hydraulic release paths being independent from each other, whereby pressure in the chamber that retains the safety valve in the open position may be released via the first or second hydraulic release path when there is a fault in the other of the first or second release path.

Abstract: A downhole system includes a drill string having a drilling fluid flow channel and at least one turbine alternator deployed in the flow channel. The turbine alternator is configured to convert flowing drilling fluid to electrical power. A voltage bus is configured to receive electrical power from the turbine alternator and at least one electrical motor is configured to receive electrical power from the voltage bus. An electronic controller is configured to provide active control of the turbine alternator via processing a desired speed of the electrical motor to generate a desired torque current and feeding the desired torque current forward to the turbine alternator. The turbine alternator is responsive to the desired torque current such that it modifies the electrical power provided to the voltage bus in response to the desired torque.

Abstract: A downhole system includes a drill string having a drilling fluid flow channel and at least one turbine alternator deployed in the flow channel. The turbine alternator is configured to convert flowing drilling fluid to electrical power. A voltage bus is configured to receive electrical power from the turbine alternator and at least one electrical motor is configured to receive electrical power from the voltage bus. An electronic controller is configured to provide active control of the turbine alternator via processing a desired speed of the electrical motor to generate a desired torque current and feeding the desired torque current forward to the turbine alternator. The turbine alternator is responsive to the desired torque current such that it modifies the electrical power provided to the voltage bus in response to the desired torque.

Abstract: A downhole system includes a drill string having a drilling fluid flow channel and at least one turbine alternator deployed in the flow channel. The turbine alternator is configured to convert flowing drilling fluid to electrical power. A voltage bus is configured to receive electrical power from the turbine alternator and at least one electrical motor is configured to receive electrical power from the voltage bus. An electronic controller is configured to provide active control of the turbine alternator via processing a desired speed of the electrical motor to generate a desired torque current and feeding the desired torque current forward to the turbine alternator. The turbine alternator is responsive to the desired torque current such that it modifies the electrical power provided to the voltage bus in response to the desired torque.

Abstract: A fault tolerant inverter or controlled rectifier system includes a first leg having at least one switch device, a spare leg having at least one spare switch device, a spare leg connect switch associated with the spare leg and the first leg, a fault detection sub-system for detecting a fault in the first leg and outputting a signal on detection of a fault in the first leg, and a leg selection control sub-system that receives the signal output by the fault detection sub-system and controls the operation of the spare leg connect switch in accordance with the output signal, such that on detection of a fault the spare leg may be activated to take over the operation of the first leg.

Abstract: A fault tolerant inverter or controlled rectifier system includes a first leg having at least one switch device, a spare leg having at least one spare switch device, a spare leg connect switch associated with the spare leg and the first leg, a fault detection sub-system for detecting a fault in the first leg and outputting a signal on detection of a fault in the first leg, and a leg selection control sub-system that receives the signal output by the fault detection sub-system and controls the operation of the spare leg connect switch in accordance with the output signal, such that on detection of a fault the spare leg may be activated to take over the operation of the first leg.

Abstract: A downhole generator system including a controlled rectifier for receiving electrical power from a generator and outputting rectified electrical power. A control system controls the operation of the controlled rectifier and a chopper circuit connected to the output of the controlled rectifier connects a load selectively across the output of the controlled rectifier to regulate the output of the generator system. The control system controls the chopper circuit and/or the controlled rectifier based at least in part on a feed-back signal representative of an electric current output by the generator system and an electric current passing through the chopper circuit.

Abstract: A downhole system includes a drill string having a drilling fluid flow channel and at least one turbine alternator deployed in the flow channel. The turbine alternator is configured to convert flowing drilling fluid to electrical power. A voltage bus is configured to receive electrical power from the turbine alternator and at least one electrical motor is configured to receive electrical power from the voltage bus. An electronic controller is configured to provide active control of the turbine alternator via processing a desired speed of the electrical motor to generate a desired torque current and feeding the desired torque current forward to the turbine alternator. The turbine alternator is responsive to the desired torque current such that it modifies the electrical power provided to the voltage bus in response to the desired torque.

Abstract: Methods comprising conveying a downhole tool within a wellbore penetrating a subterranean formation, wherein the downhole tool comprises a first pump and a second pump, and wherein at least one operational capability of the first and second pumps is substantially different. A fracture is initiated in the subterranean formation by pumping fluid into the formation using the first pump. The fracture is propagated in the subterranean formation by pumping fluid into the formation using the second pump.

Abstract: Methods comprising conveying a downhole tool within a wellbore penetrating a subterranean formation, wherein the downhole tool comprises a first pump and a second pump, and wherein at least one operational capability of the first and second pumps is substantially different. A fracture is initiated in the subterranean formation by pumping fluid into the formation using the first pump. The fracture is propagated in the subterranean formation by pumping fluid into the formation using the second pump.