Integrated modulator and turbine-generator for a measurement while drilling tool
First Claim
1. An apparatus for use in a borehole having borehole fluid flowing therethrough, said apparatus comprising:
- a) a tool housing having an open end for receiving the borehole fluid;
b) a drive shaft mounted for rotation in said housing;
c) a turbine impeller mechanically coupled to said drive shaft such that the flowing borehole fluid causes said turbine impeller to rotate;
d) a modulator rotor mechanically coupled to said drive shaft such that rotation of said turbine impeller causes said modulator rotor to rotate;
e) a modulator stator mounted in said housing adjacent said modulator rotor such that rotation of said modulator rotor relative to said modulator stator creates pressure pulses in the borehole fluid; and
f) a controllable braking means for selectively braking rotation of said modulator rotor to modulate said pressure pulses.
1 Assignment
0 Petitions
Accused Products
Abstract
An integrated modulator and turbine-generator includes a turbine impeller which is directly coupled by a drive shaft to a modulator rotor downstream from the impeller. The modulator rotor is further coupled by a drive shaft and a gear train to a three phase alternator downstream of the modulator rotor. The modulator stator blades are arranged downstream of and adjacent to the modulator rotor and the alternator is provided with a Hall effect tachometer. The turbine impeller directly drives the modulator rotor and the alternator generates power. The speed of rotation of the modulator rotor is adjusted by reference to the speed of rotation of the alternator as indicated by the tachometer and to a reference frequency. A control circuit including an electromagnetic braking circuit coupled to the tachometer and the stator windings of the alternator stabilizes the alternator speed and thus the rotor speed and modulates the rotor to obtain the desired frequency of the mudborne pressure wave by selectively shorting the stator windings of the alternator. During periods when braking is not applied, the alternator generates power for control and sensor electronics.
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Citations
28 Claims
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1. An apparatus for use in a borehole having borehole fluid flowing therethrough, said apparatus comprising:
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a) a tool housing having an open end for receiving the borehole fluid; b) a drive shaft mounted for rotation in said housing; c) a turbine impeller mechanically coupled to said drive shaft such that the flowing borehole fluid causes said turbine impeller to rotate; d) a modulator rotor mechanically coupled to said drive shaft such that rotation of said turbine impeller causes said modulator rotor to rotate; e) a modulator stator mounted in said housing adjacent said modulator rotor such that rotation of said modulator rotor relative to said modulator stator creates pressure pulses in the borehole fluid; and f) a controllable braking means for selectively braking rotation of said modulator rotor to modulate said pressure pulses. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 22)
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21. An apparatus for use in a borehole having borehole fluid flowing therethrough, said apparatus comprising:
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a) a tool housing having an open upper end for receiving the borehole fluid; b) a drive shaft mounted for rotation in said housing; c) a turbine impeller mechanically coupled to said drive shaft and facing said open upper end such that the flowing borehole fluid causes said turbine impeller to rotate; d) a modulator rotor mechanically coupled to said drive shaft downstream from said turbine impeller such that rotation of said turbine impeller causes said modulator rotor to rotate; e) a modulator stator mounted in said housing adjacent said modulator rotor such that rotation of said modulator rotor relative to said modulator stator creates pressure pulses in the borehole fluid; and f) a controllable braking means for selectively braking rotation of said modulator rotor to modulate said pressure pulses.
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23. A method for modulating a pressure wave in a flow path of drilling fluid being circulated in a borehole, said method comprising:
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a) providing a turbine impeller in the flow path of the drilling fluid so that the circulation of the drilling fluid imparts rotation to said turbine impeller; b) mechanically coupling a modulator rotor to the impeller in the flow path so that rotation of said turbine impeller causes rotation of said modulator rotor; c) providing a modulator stator adjacent said modulator rotor so that rotation of said modulator rotor relative to said modulator stator interrupts the circulation of the drilling fluid and produces the pressure wave in the flow path of the drilling fluid; and d) selectively braking rotation of said modulator rotor to modulate the pressure wave in the flow path of the drilling fluid. - View Dependent Claims (24, 25, 26, 27, 28)
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Specification