Mud pulser with poppet valve, having linear displacement determination means

摘要

A measurement-while-drilling servo-actuator for use in mud-pulse telemetry, which determines linear position of a poppet valve therein without counting revolutions of a stepper motor which positions said poppet valve. A sensor senses a magnetic field intensity value, or an inductance value, which is proportional to the position of the poppet valve relative to the sensor. A look-up table of reference outputs corresponding to known position of the poppet valve is used to determine the position of the poppet valve. A method of determining a position of a poppet valve in a mud pulser is further disclosed.

主权项

1. A measurement-while-drilling servo-actuator for use in mud-pulse telemetry downhole below earth's surface, which reduces or eliminates overdriving of a valve therein and thereby avoids wastage of battery life: comprising:
(i) a poppet valve, linearly moveable between an open position which permits flow of pressurized drilling mud through a servo-valve port and a closed or substantially closed position wherein said poppet valve obstructs said servo-valve port to prevent or substantially prevent flow of said pressurized drilling mud therethrough; (ii) an electric motor having at one end thereof an output shaft that rotates in response to operation of the electric motor; (iii) a battery, electrically coupled to said electric motor to provide electrical current when desired to said electric motor to cause said electric motor to turn in a first direction or in a second opposite direction; (iv) a rotary-to-linear motion converter mechanically coupled at one end thereof to said poppet valve, for linearly moving said poppet valve back and forth between said closed position and said open position; (v) a sensor for sensing proximity of said poppet valve to said sensor and providing an output proportional to proximity of said poppet valve to said sensor; and (vi) a controller for receiving data as to downhole conditions to and controlling the electric motor to open and close the poppet valve-for varying times and durations to thereby cause flow of said pressurized drilling mud therethrough to vary in a coded sequence so as to thereby transmit said data as to said downhole conditions in said coded sequence uphole to said earth's surface via resulting-pressure pulses in said pressurized drilling mud, said controller in electrical communication with said sensor and further configured for receiving said output from said sensor and determining poppet valve position therefrom, wherein if said poppet valve is determined by said controller as a result of said output received from said sensor to have reached said closed position when said electric motor is turning in said first direction, said controller is configured to ceases allowing said battery to provide said current to said electric motor to turn said electric motor in said first direction and thereby stops forcing said poppet valve into said closed position and thus prevents unneeded consumption of said electrical current from said battery.