초록 ▼

A drilling assembly positionable in a well bore includes a turbine motor couplable to a drill string and a harmonic drive transmission coupled to the turbine motor. The harmonic drive transmission includes a circular spline, a wave generator, a flexspline, and a sealing subsystem. The sealing subsys

A drilling assembly positionable in a well bore includes a turbine motor couplable to a drill string and a harmonic drive transmission coupled to the turbine motor. The harmonic drive transmission includes a circular spline, a wave generator, a flexspline, and a sealing subsystem. The sealing subsystem defines a substantially sealed volume containing the circular spline, wave generator, and flexspline, and isolates the circular spline, wave generator, and flexspline from drilling fluid exiting the turbine motor and flowing through the harmonic drive transmission.

대표청구항 ▼

1. A drilling assembly positionable in a wellbore, the assembly including: a turbine motor couplable to a drill string; anda harmonic drive transmission coupled to the turbine motor, the harmonic drive transmission comprising: a circular spline;a wave generator coupled to an input shaft;a flexspline

1. A drilling assembly positionable in a wellbore, the assembly including: a turbine motor couplable to a drill string; anda harmonic drive transmission coupled to the turbine motor, the harmonic drive transmission comprising: a circular spline;a wave generator coupled to an input shaft;a flexspline coupled to an output shaft;a sealing subsystem including: an upper rotary seal disposed around the input shaft;a lower rotary seal disposed around the output shaft; anda drilling fluid diversion subsystem comprising a drilling fluid flow path including a drilling fluid inlet on the input shaft leading to a bore of the input shaft, and a drilling fluid outlet on the output shaft leading to a bore of the output shaft, the input shaft extending through a central opening defined by a central passage of the wave generator, a central passage of the flexspline, and a central passage of the circular spline to couple with the output shaft, such that the bore of the input shaft is in fluid communication with the bore of the output shaft. 2. The drilling assembly of claim 1, wherein the drilling fluid inlet is located above the upper rotary seal, and wherein the drilling fluid outlet is located below the lower rotary seal. 3. The drilling assembly of claim 1, wherein the wave generator comprises an elliptical cam disk having a smooth outer surface bearing against a flexible wall of the flexspline. 4. The drilling assembly of claim 1, wherein the flexspline comprises a substantially rigid base supporting a flexible wall, and wherein the output shaft is connected to the rigid base of the flexspline. 5. The drilling assembly of claim 1, wherein an outer surface of a flexible wall of the flexspline includes a radial pattern of gear teeth complementary to a radial pattern of gear teeth on an inner surface of the circular spline. 6. The drilling assembly of claim 5, wherein the flexspline includes less gear teeth than the circular spline. 7. The drilling assembly of claim 5, wherein an outer diameter of the circular spline is greater than an outer diameter of the flexspline. 8. The drilling assembly of claim 1, wherein the upper rotary seal comprises a spring-loaded balance piston. 9. The drilling assembly of claim 1, wherein the sealed volume contains lubricant oil. 10. The drilling assembly of claim 1, wherein the harmonic drive transmission comprises a first harmonic drive transmission, and wherein the drilling assembly further comprises a second harmonic drive transmission coupled to the first harmonic drive transmission. 11. The drilling assembly of claim 10, wherein the first harmonic drive transmission and the second harmonic drive transmission have different gear ratios. 12. The drilling assembly of claim 1, wherein the input shaft is coupled to a motor shaft of the turbine motor by a detachable spline coupling. 13. The drilling assembly of claim 1, wherein the output shaft is coupled to an articulated extension rod by a detachable spline coupling. 14. The drilling assembly of claim 1, wherein the sealing subsystem defines a substantially sealed volume containing the circular spline, wave generator, and flexspline, and isolates the circular spline, wave generator, and flexspline from drilling fluid exiting the turbine motor and flowing through the harmonic drive transmission. 15. A method conducting drilling operations in a wellbore, the method comprising: attaching a turbine motor to a drill string;coupling a harmonic drive transmission to the turbine motor, the harmonic drive transmission comprising: a circular spline;a wave generator coupled to an input shaft;a flexspline coupled to an output shaft;a sealing subsystem including: an upper rotary seal disposed around the input shaft;a lower rotary seal disposed around the output shaft;a drilling fluid diversion subsystem comprising a drilling fluid flow path including a drilling fluid inlet on the input shaft leading to a bore of the input shaft; and a drilling fluid outlet on the output shaft leading to a bore of the output shaft, the input shaft extending through a central opening defined by a central passage of the wave generator, a central passage of the flexspline, and a central passage of the circular spline to couple with the output shaft, such that the bore of the input shaft is in fluid communication with the bore of the output shaft; andpositioning the drill string and the turbine motor and the harmonic drive transmission in the well bore. 16. The method of claim 15, further comprising: flowing drilling fluid down the drill string and through the turbine motor;routing, with a drilling fluid diversion subsystem, drilling fluid from the turbine motor towards a lower end of the tool string; andinhibiting, with the sealing subsystem, drilling fluid flowing through the drilling fluid flow path from contacting the circular spline, wave generator, and flexspline. 17. The method of claim 16, wherein routing drilling fluid comprises: flowing drilling fluid through the bore of the input shaft;flowing drilling fluid passed the coupling between the input shaft and the output shaft; andflowing drilling fluid through the bore of the output shaft. 18. A drilling assembly positionable in a wellbore, the assembly including: a turbine motor couplable to a drill string;a first transmission coupled to the turbine motor, the first transmission comprising: a circular spline;a wave generator coupled to an input shaft; anda flexspline coupled to an output shaft;a second transmission coupled to the first transmission; anda drilling fluid diversion subsystem configured to route drilling fluid from the turbine motor through a drilling fluid flow path including a drilling fluid inlet on the input shaft leading to a bore of the input shaft, and a drilling fluid outlet on the output shaft leading to a bore of the output shaft, the input shaft extending extending along a shared axis of the circular spline, wave generator, and flexspline of the first transmission to couple with the output shaft, such that the bore of the input shaft is in fluid communication with the bore of the output shaft. 19. The drilling assembly of claim 18, wherein the first transmission further comprises: a sealing subsystem including: an upper rotary seal disposed around the input shaft;a lower rotary seal disposed around the output shaft; andan inner rotary seal located at a coupling between the input shaft and the output shaft. 20. The drilling assembly of claim 18, wherein the first and second transmissions are supported in a shared transmission housing. 21. The drilling assembly of claim 18, wherein the first and second transmissions are supported in separate transmission housings. 22. The method of claim 15, wherein the sealing subsystem defines a substantially sealed volume containing the circular spline, wave generator, and flexspline, and isolates the circular spline, wave generator, and flexspline from drilling fluid exiting the turbine motor and flowing through the harmonic drive transmission. 23. The drilling assembly of claim 19, wherein the sealing subsystem defines a substantially sealed volume containing the circular spline, wave generator, and flexspline, and isolates the circular spline, wave generator, and flexspline from drilling fluid exiting the turbine motor and flowing through the first transmission.