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An anti-plugging oscillating shear valve system for generating pressure fluctuations in a flowing drilling fluid comprising a stationary stator and an oscillating rotor, both with axial flow passages. The rotor oscillates in close proximity to the stator, at least partially blocking the flow through

An anti-plugging oscillating shear valve system for generating pressure fluctuations in a flowing drilling fluid comprising a stationary stator and an oscillating rotor, both with axial flow passages. The rotor oscillates in close proximity to the stator, at least partially blocking the flow through the stator and generating oscillating pressure pulses. The rotor passes through two zero speed positions during each cycle, facilitating rapid changes in signal phase, frequency, and/or amplitude facilitating enhanced data encoding. The rotor is driven by a electric motor disposed in a lubricant filled housing. In one embodiment, the housing to shaft seal is a flexible bellows. In one embodiment, a torsional spring is attached to the motor and the resulting spring mass system is designed to be near resonance at the desired pulse frequency. The torsion spring may be a solid torsion bar or a magnetic spring.

대표청구항 ▼

An anti-plugging oscillating shear valve system for generating pressure fluctuations in a flowing drilling fluid comprising a stationary stator and an oscillating rotor, both with axial flow passages. The rotor oscillates in close proximity to the stator, at least partially blocking the flow through

An anti-plugging oscillating shear valve system for generating pressure fluctuations in a flowing drilling fluid comprising a stationary stator and an oscillating rotor, both with axial flow passages. The rotor oscillates in close proximity to the stator, at least partially blocking the flow through the stator and generating oscillating pressure pulses. The rotor passes through two zero speed positions during each cycle, facilitating rapid changes in signal phase, frequency, and/or amplitude facilitating enhanced data encoding. The rotor is driven by a electric motor disposed in a lubricant filled housing. In one embodiment, the housing to shaft seal is a flexible bellows. In one embodiment, a torsional spring is attached to the motor and the resulting spring mass system is designed to be near resonance at the desired pulse frequency. The torsion spring may be a solid torsion bar or a magnetic spring. n claim 4 wherein the annular cup comprises a steel ring bonded to a depending elastic cup so that the fluid pressure exerts an axial force against the annular cup to force the steel ring against the annular sealing element. 6. An apparatus as claimed in claim 5 wherein the annular cup includes at least one O-ring mounted in respective grooves in an inner surface of the steel ring to seal an annulus between the cup tool and the annular cup. 7. An apparatus as claimed in claim 1 wherein the fracturing head includes a mandrel head mounted to a top of the mandrel, the mandrel head including a top flange, and the fracturing head is mounted to the top flange of the mandrel head. 8. An apparatus as claimed in claim 7 wherein the lock mechanism comprises a spiral thread on the base member engaged by a complementary thread of a lockdown nut rotatably connected to a bottom flange of the mandrel head to lock the mandrel head against the base member to inhibit upwards movement of the mandrel induced by fluid pressure in the wellbore when the mandrel is in the operative position. 9. An apparatus as claimed in claim 1 wherein the apparatus further includes a blast joint through which the tubing string is run, the blast joint protecting the tubing string from erosion when abrasive fluids are pumped through the at least one radial passage in the fracturing head. 10. An apparatus as claimed in claim 9 wherein the blast joint is connected to the tubing adapter. 11. An apparatus for protecting a blowout preventer from exposure to fluid pressures, abrasives and corrosive fluids used in a well treatment to stimulate production and for supporting a tubing string in a wellbore of a well so that the tubing string is accessible during the well treatment, the apparatus including a mandrel adapted to be inserted down through the blowout preventer to an operative position, and a base member adapted for connection to a wellhead, the base member including fluid seals through which the mandrel is reciprocally movable, comprising: a fracturing head including a central passage in fluid communication with the mandrel and at least one radial passage in fluid communication with the central passage; a tubing adapter mounted to a top end of the fracturing head, including a first threaded connector to permit connection of the tubing string so that the tubing string is suspended from the tubing adapter; a sealing assembly attached to a bottom end of the mandrel to seal an annulus between the mandrel and a casing of the well when the mandrel is in the operative position; and a mechanical lockdown mechanism for locking the apparatus in the operative position to inhibit upward movement of the mandrel induced by fluid pressures in the wellbore, including a spiral thread on the base member engaged by a complementary thread of a lockdown nut rotatably connected to the fracturing head to lock the fracturing head against the base member for transferring the weight of the tubing string to the wellhead. 12. An apparatus as claimed in claim 11 wherein the tubing adapter further includes a second threaded connector to permit the connection of a valve to permit fluids to be pumped through the tubing string. 13. An apparatus as claimed in claim 11 wherein the sealing assembly comprises a resilient annular sealing element and an annular cup, the annular cup being adapted to be forced upwards under fluid pressure to compress the annular sealing element so that the annular sealing element radially expands against an inner wall of the casing to provide a high pressure fluid seal in the annulus. 14. An apparatus as claimed in claim 13 wherein the sealing assembly further includes an annular cup tool connected to a bottom end of the mandrel, the annular cup tool including a radial retainer shoulder adjacent a bottom end of the mandrel, an annular gauge ring located between the radial retainer shoulder and a top end of the annular sealing element to retain the annular sealing e