System And Method For Wireless Power And Data Transmission In A Rotary Steerable System

• US 20140084946A1
• Filed: 03/14/2013
• Published: 03/27/2014
• Est. Priority Date: 09/24/2012
• Status: Abandoned Application

• Current Assignee: Schlumberger Technology Corporation (Schlumberger NV)
• Original Assignee: Schlumberger Technology Corporation (Schlumberger NV)
• Inventors: Clark, Brian Oliver, Moriarty, Keith A., Gadot, Raphael
• Application Number:
  US13/802,746
• Publication Number:
  US 20140084946A1
• Time in Patent Office: Days
• US Class Current: 324/654
• CPC Class Codes: E21B 47/13 by electromagnetic energy, e.g. radio frequency
• CPC Class Codes: G01N 27/02 by investigating impedance
• CPC Class Codes: H02J 50/005 Mechanical details of housing or structure aiming to accommodate the power transfer means, e.g. mechanical integration of coils, antennas or transducers into emitting or receiving devices
• CPC Class Codes: H02J 50/12 of the resonant type
• CPC Class Codes: H02J 50/80 involving the exchange of data, concerning supply or distribution of electric power, between transmitting devices and receiving devices

Abstract

Various embodiments for wireless power and data communications transmissions between a cartridge in a rotary steering system and components within a drill collar are disclosed. In a certain embodiment, magnetic fields are used to transfer power and data between the cartridge of a rotary steering system and electronics and/or sensors mounted in the drill collar. A first coil is attached to the pressure housing of the cartridge by a shaft containing wires. The turbine in the pressure housing provides an alternating current to the first coil, which is attached to the shaft. Consequently, the first coil generates an alternating magnetic field that passes through the ferrite surrounding a second coil that is attached by wires to an annular pressure housing that is attached to the drill collar. The alternating magnetic field generates an emf in the second coil, which provides power for electronics and sensors mounted in the drill collar.

Claims

1. A method for transmitting electrical power to a sensor in a drill collar of a rotary steerable system from a power source in a cartridge that resides within the drill collar, the method comprising:

inductively coupling a pair of coils comprising a primary coil and a secondary coil, wherein;

the primary coil is a mandrel coil associated with the cartridge and the secondary coil is an annular coil associated with the drill collar; and

the primary coil is substantially positioned within a space defined by the secondary coil;

providing power from the power source to the primary coil via a wired connection, wherein provision of the power to the primary coil causes power to be transmitted to the inductively coupled secondary coil; and

providing power from the secondary coil to the sensor via a wired connection.

2. The method of claim 1, wherein the coupling coefficient, k, of the pair of coils is determined as k=M/√

{square root over (L₁L₂)}, wherein k is the coupling coefficient of the coils, M is the mutual inductance between the coils, and L₁ and L₂ are the self-inductances of the primary and secondary coils, respectively.

3. The method of claim 2, wherein the coils are loosely coupled such that k is less than or equal to approximately 0.9.

4. The method of claim 1, further comprising resonantly tuning the pair of coils with capacitors such that the coils resonate at approximately the same frequency.

5. The method of claim 4, wherein each coil is resonantly tuned with a capacitor such that:

f₁≈

f₂, wherein

6. The method of claim 1, wherein a figure of merit, U, associated with the pair of coils is equal to or greater than 3.

7. The method of claim 6, wherein U is determined as U=k√

{square root over (Q₁Q₂)}, wherein

8. The method of claim 1, wherein each of the pair of coils is associated with a high quality factor, Q, that is equal to or greater than 10.

9. The method of claim 1, further comprising approximately matching an impedance of the source, R_S, with an impedance of a load by setting:

R_S≈

R₁√

{square root over (1+k²Q₁Q₂)},

wherein R₁ is the series resistance of the primary coil, k is the coupling coefficient of the pair of coils, Q₁ is the quality factor associated with primary coil and Q₂ is the quality factor associated with the secondary coil.

10. The method of claim 1, further comprising approximately matching an impedance of a load, R_L, with an impedance of the source by setting:

R_L≈

R₂√

{square root over (1+k²Q₁Q₂)},

wherein R₂ is the series resistance of the secondary coil, k is the coupling coefficient of the pair of coils, Q₁ is the quality factor associated with primary coil and Q₂ is the quality factor associated with the secondary coil.

11. The method of claim 1, wherein the secondary coil comprises a wire wrapped on a cylinder comprised of ferrite.

12. The method of claim 1, wherein the primary coil comprises a wire wrapped on a core comprised of ferrite.

13. The method of claim 1, wherein the power transferred from the primary coil to the inductively coupled secondary coil comprises data in the form of a modulated amplitude, phase or frequency of a current that drives the primary coil.

14. A system for transmitting electrical power to a sensor in a drill collar of a rotary steerable system from a power source in a cartridge that resides within the drill collar, the system comprising:

an inductively coupled pair of coils comprising a primary coil and a secondary coil, wherein;

the primary coil is a mandrel coil associated with the cartridge and the secondary coil is an annular coil associated with the drill collar; and

the primary coil is substantially positioned within a space defined by the secondary coil;

a power source within the cartridge coupled to the primary coil via a wired connection and operable to provide power to the primary coil, wherein provision of the power to the primary coil causes power to be transmitted to the inductively coupled secondary coil; and

a wired connection operable to provide power from the secondary coil to the sensor.

15. The system of claim 14, wherein the coupling coefficient, k, of the pair of coils is less than or equal to 0.9.

16. The system of claim 14, wherein the pair of coils are resonantly tuned with a capacitor such that the coils resonate at approximately the same frequency.

17. The system of claim 14, wherein a figure of merit, U, associated with the pair of coils is equal to or greater than 3.

18. The system of claim 14, wherein each of the pair of coils is associated with a high quality factor, Q, that is equal to or greater than 10.

19. The system of claim 14, wherein the impedance of the source, R_S, is approximately matched with an impedance of a load by setting:

R_S≈

R₁√

{square root over (1+k²Q₁Q₂)},

wherein R₁ is the series resistance of the primary coil, k is the coupling coefficient of the pair of coils, Q₁ is the quality factor associated with primary coil and Q₂ is the quality factor associated with the secondary coil.

20. The system of claim 14, wherein the impedance of a load, R_L, is approximately matched with an impedance of the source by setting:

R_L≈

R₂√

{square root over (1k²Q₁Q₂)},

wherein R₂ is the series resistance of the secondary coil, k is the coupling coefficient of the pair of coils, Q₁ is the quality factor associated with primary coil and Q₂ is the quality factor associated with the secondary coil.

21. The system of claim of claim 14, comprising a first antenna mounted in a groove on the drill collar of the rotary steerable system, the first short hop antenna being operatively coupled to transmitting and receiving electronics powered by the secondary coil, wherein the first antenna is configured to transmit data by electromagnetic telemetry using short hop communication to a second antenna mounted in a grove on a drill collar of a measure-while-drilling (MWD) tool.

22. The system of claim 21, wherein the first antenna and the second antenna are separated by at least fifty feet.

23. A method for transmitting electrical power to a sensor in a drill collar of a measure-while-drilling tool from a power source that resides within the drill collar, the method comprising:

inductively coupling a pair of coils comprising a primary coil and a secondary coil, wherein the primary coil is wound about a pressure housing disposed in the drill collar and the secondary coil is mounted on the inner diameter of the drill collar, wherein the primary coil is substantially positioned within a space defined by the secondary coil;

providing power from the power source to the primary coil via a wired connection, wherein provision of the power to the primary coil causes power to be transmitted to the inductively coupled secondary coil; and

providing power from the secondary coil to the sensor via a wired connection.

24. The method of claim 23, wherein the coupling coefficient, k, of the pair of coils is determined as k=M/√

{square root over (L₁L₂)}, wherein k is the coupling coefficient of the coils, M is the mutual inductance between the coils, and L₁ and L₂ are the self-inductances of the primary and secondary coils, respectively, and wherein the primary and secondary coils are loosely coupled such that k is less than or equal to approximately 0.9.

25. The method of claim 23, wherein the pair of coils are tuned with capacitors such that the coils resonate at approximately the same frequency f₁≈

f₂, wherein

26. The method of claim 23, wherein a figure of merit, U, is determined as U=k√

{square root over (Q₁Q₂)}, wherein

27. The method of claim 26, wherein each of the pair of coils is associated with a high quality factor, Q, that is equal to or greater than 10.