Inductive Coupler for Downhole Drilling Power Transfer

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Solution Overview

Problem

Existing downhole drilling devices face challenges in efficiently transferring power from rotating to non-rotating parts due to high power losses and mechanical contact issues with slip-ring devices, limiting design flexibility and increasing costs.

Innovation Solution

The use of an inductive coupler with a primary and secondary side to wirelessly transfer power and data between rotating and non-rotating parts of the drilling device, powered by a downhole mud turbine generator, allowing for a self-contained, fully electric directional drilling system.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Loss of energy

If mechanical contact devices (slip-ring devices) are used to transfer power from rotating to non-rotating parts, then power transfer is achieved, but high power losses and temperature increases occur due to wear and contact resistance

Engineering Contradiction:

Improvepower lossesVSAvoiddevice reliability

Core Design Contradiction:

Loss of energyVSReliability

Solution Approach 1:

The patent replaces mechanical contact devices (slip-ring devices) with an inductive coupling system that uses electromagnetic fields to transfer power. The primary winding on the rotating drill string and secondary winding on the non-rotating bottom hole assembly create magnetic coupling without physical contact, eliminating wear and contact resistance while maintaining reliable power transfer.

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

2Loss of energy

If long wires are used to transfer power from surface to downhole components, then power supply is achieved, but design options are limited and power is lost during transfer

Engineering Contradiction:

Improvepower loss during transferVSAvoiddesign options

Core Design Contradiction:

Loss of energyVSAdaptability or versatility

Solution Approach 1:

The patent replaces long electrical wires with an inductive power transfer system using electromagnetic coupling between primary and secondary windings. This eliminates power loss in wire transfers and provides design flexibility by enabling power transfer across rotating and non-rotating interfaces without physical wire connections.

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

3Duration of action of moving object

If battery packs are used to power downhole components, then power supply is achieved, but lifetime between runs is limited and device length and running cost increase

Engineering Contradiction:

Improvelifetime between runsVSAvoiddevice length

Core Design Contradiction:

Duration of action of moving objectVSLength of moving object

Solution Approach 1:

The patent replaces battery packs with an inductive power transfer system that continuously supplies power from the surface through electromagnetic coupling. This eliminates the need for finite-capacity batteries, enabling unlimited operational duration without increasing device length, as power is transferred through the drill string and bottom hole assembly structure.

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

4Loss of energy

If inductive coupling is used to transfer power across rotating connections, then power transfer efficiency is improved and design is simplified, but robust solution for continuous rotation must be ensured

Engineering Contradiction:

Improvepower lossesVSAvoidrobustness of rotating connection

Core Design Contradiction:

Loss of energyVSReliability

Solution Approach 1:

The patent uses inductive coupling with primary and secondary windings that create magnetic coupling across the rotating interface. This electromagnetic coupling maintains constant power transfer efficiency regardless of rotational position or speed, and the magnetic field naturally accommodates continuous rotation without mechanical wear or contact issues.

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

Applied Scientific Principles

This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.

Function Achieved in This Case

This solution significantly reduces power losses, simplifies device design, and enables efficient power transfer across rotating connections, enhancing drilling efficiency and reducing operational costs by eliminating the need for surface power supply and mechanical contact devices.

Implementation Method 1

an inductive coupler having a primary side and a secondary side, said inductive coupler being adapted to transfer power from said power source, connected to the primary side of said inductive coupler, to said guiding device, connected to the secondary side of said inductive coupler

Methodology Applied

Scientific EffectElectromagnetic induction: Electromagnetic Induction

Data Source

PatentUS9957761B2Downhole drilling device

Publication Date: 2018.05.01 NABORS LUX 2 SARL

AI summary

A downhole drilling device (1) may include a drill bit rotatable via a drill string (11); a guiding device (4) provided between said drill bit and said drill string (11), said guiding device (4) being connected to and operable independently from said drill string (11); and a power source (5) for powering said guiding device (4). The downhole drilling device (1) may include an inductive coupler (6, 6′) having a primary side (61) and a secondary side (63), said inductive coupler (6, 6′) being adapted to transfer power from said power source (5), connected to the primary side (61) of said inductive coupler (6, 6′), to said guiding device (4), connected to the secondary side (63) of said inductive coupler (6, 6′).