System And Method For Power Transmission In A Bottom Hole Assembly
First Claim
1. A method for transmitting electrical power from a power source located above a positive displacement motor (“
- PDM”
) in a bottom hole assembly of a drill string to a sensor subassembly located below the PDM in the drill string, the method comprising;
inductively coupling a pair of coils comprising a primary coil and a secondary coil, wherein;
the coils are located above the PDM;
the primary coil is an annular coil and the secondary coil is a mandrel coil extending from a rotor of the PDM;
the secondary coil is substantially positioned within a space defined by the primary coil;
the coils are loosely coupled such that;
k=M/√
{square root over (L1L2)}≦
0.9, 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 respective coils;
each coil is resonantly tuned with a capacitor such that;
f1≈
f2, wherein
1 Assignment
0 Petitions
Accused Products
Abstract
Various embodiments of methods and systems for wireless power and data communications transmissions to a sensor subassembly below a mud motor in a bottom hole assembly are disclosed. In a certain embodiment, a float valve is located above the motor. Power is supplied by a turbine or by batteries located in a subassembly above the float valve. Wires pass through the float valve and connect to an annular coil. Power is transmitted through the annular coil to an inductively coupled second, mandrel coil that is attached to the rotor. By leveraging resonantly tuned circuits and impedance matching techniques for the coils, power can be transmitted efficiently from one coil to the other despite relative movement and misalignment of the two coils.
10 Citations
20 Claims
-
1. A method for transmitting electrical power from a power source located above a positive displacement motor (“
- PDM”
) in a bottom hole assembly of a drill string to a sensor subassembly located below the PDM in the drill string, the method comprising;inductively coupling a pair of coils comprising a primary coil and a secondary coil, wherein; the coils are located above the PDM; the primary coil is an annular coil and the secondary coil is a mandrel coil extending from a rotor of the PDM; the secondary coil is substantially positioned within a space defined by the primary coil; the coils are loosely coupled such that;
k=M/√
{square root over (L1L2)}≦
0.9, 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 respective coils;each coil is resonantly tuned with a capacitor such that;
f1≈
f2, wherein - View Dependent Claims (2, 3, 4, 5, 6)
- PDM”
-
7. A method for transmitting electrical power from a power source located above a positive displacement motor (“
- PDM”
) in a bottom hole assembly of a drill string to a sensor subassembly located below the PDM in the drill string, the method comprising;inductively coupling a pair of coils comprising a primary coil and a secondary coil, wherein; the coils are located above the PDM; the primary coil is an annular coil and the secondary coil is a mandrel coil extending from a rotor of the PDM; and the secondary coil is substantially positioned within a space defined by the primary 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 subassembly via a wired connection that passes through the rotor of the PDM. - View Dependent Claims (8, 9, 10, 11, 12, 13)
- PDM”
-
14. A system for transmitting electrical power from a power source located above a positive displacement motor (“
- PDM”
) in a bottom hole assembly of a drill string to a sensor subassembly located below the PDM in the drill string, the system comprising;an inductively coupled pair of coils comprising a primary coil and a secondary coil, wherein; the coils are located above the PDM; the primary coil is an annular coil and the secondary coil is a mandrel coil extending from a rotor of the PDM; and the secondary coil is substantially positioned within a space defined by the primary coil; a power source 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 through the rotor of the PDM operable to provide power from the secondary coil to the sensor subassembly. - View Dependent Claims (15, 16, 17, 18, 19, 20)
- PDM”
Specification