Apparatus for electrical power and/or data transfer between rotating components in a drill string

Abstract

A downhole tool includes a non-contact, electrical coupling device configured to transmit electrical power and / or data between relatively rotating components. In one embodiment, the coupling device includes at least first and second wound toroidal cores deployed about a shaft. At least one of the wound toroidal cores is rotationally fixed to the shaft, while at least one other is rotationally fixed to a housing in which the shaft is deployed. The shaft forms a portion of a conductive loop that extends through the toroids. A non-contact electrical pathway is advantageously provided for high power electrical transmission and / or high speed data transmission across a gap between first and second rotating members of a downhole assembly.

Description

RELATED APPLICATIONS[0001]None.FIELD OF THE INVENTION[0002]The present invention relates generally to downhole tools having rotating components, for example, including directional drilling tools such as a steering tool or a mud motor. More particularly, embodiments of this invention relate to a downhole assembly including a non-contact apparatus for transmitting electrical power and / or data between first and second members of the assembly that are disposed to rotate with respect to one another (such as a shaft rotating in a housing).BACKGROUND OF THE INVENTION[0003]As is well-known in the industry, hydrocarbons are recovered from subterranean reservoirs by drilling a borehole (wellbore) into the reservoir. Such boreholes are commonly drilled using a rotating drill bit attached to the bottom of a drilling assembly (which is commonly referred to in the art as a bottom hole assembly or a BHA). The drilling assembly is commonly connected to the lower end of a drill string including a lo...

AI Technical Summary

Benefits of technology

[0010]Exemplary embodiments of the present invention may advantageously provide several technical advantages. For example, exemplary embodiments of this invention provide a non-contact, high-power electrical transmission path and a high-speed data communication channel across a gap between first and second rotating members of a downhole assembly. Moreover, exemplary embodiments of the invention also provide for simultaneous non-contact transmission of electrical power between the first and second tool members.

[0011]Exemplary embodiments of the invention may be advantageously configured for high-power and high-efficiency electrical transmission (especially as compared with conventional inductive coupling devices). Moreover, the invention does not utilize a magnetic field to transmit electrical energy across an air gap (as with prior art inductive couplings). Those of ordinary skill in the art will appreciate that the presence of the air gap in an inductive coupling reduces the effective magnetic permeability of the magnetic path, which can significantly reduce the overall efficiency of the coupling. The invention utilizes the afore-mentioned low impedance conductive loop to transmit electrical energy between the rotating components and is therefore advantageously unaffected by the clearance (the size of the gap) between the rotating components (e.g., between the shaft and housing on a rotary steerable tool) or between similar parts of a rotary transformer.

Problems solved by technology

Those of ordinary skill in the art will appreciate that the presence of the air gap in an inductive coupling reduces the effective magnetic permeability of the magnetic path, which can significantly reduce the overall efficiency of the coupling.

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