Dual-Walled Running String Power Transmission via Skin Effect

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Solution Overview

Problem

Conventional running strings for downhole electrically operated tools, such as electric submersible pumps, face issues with power cable failure due to wellbore debris and corrosion, which can disrupt the operation of ESPs and other devices.

Innovation Solution

A dual-walled running string formed of coiled tubing or interconnected conventional oilfield tubulars is used to transmit power to ESPs and other devices, utilizing a conductive shroud to communicate power via skin effect, eliminating the need for a surface power cable and providing backup power in case of primary cable failure.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If a conventional power cable is used to transmit power to the ESP, then power transmission is achieved, but the system reliability deteriorates due to wellbore debris and corrosion causing cable failure

Engineering Contradiction:

Improvepower transmission reliabilityVSAvoidwellbore debris and corrosion

Core Design Contradiction:

ReliabilityVSObject-affected harmful factors

Solution Approach 1:

The patent extracts the power transmission function from the conventional separate power cable and integrates it into the running string itself. The running string is converted into a conductive power transmission medium, eliminating the need for a separate vulnerable power cable that is exposed to wellbore debris and corrosion.

Inventive Principle:

Principle #2Taking out (Extraction)

Solution Approach 2:

The patent merges the mechanical support function of the running string with the electrical power transmission function by making the running string itself conductive. This combines two previously separate functions (mechanical support and power transmission) into a single integrated system, reducing the number of separate components exposed to harmful wellbore conditions.

Inventive Principle:

Principle #5Merging (Combining)

2Object-affected harmful factors

If an armored power cable is used to protect against wellbore debris and corrosion, then protection is improved, but the device complexity and potential failure points increase

Engineering Contradiction:

Improveprotection against wellbore debris and corrosionVSAvoidpower cable structure complexity

Core Design Contradiction:

Object-affected harmful factorsVSDevice complexity

Solution Approach 1:

The patent removes the complex armored power cable structure entirely and replaces it with a simpler conductive running string. By extracting the power transmission function from the separate armored cable and integrating it into the running string, the system eliminates the complexity of armored cable construction while maintaining protection against wellbore conditions.

Inventive Principle:

Principle #2Taking out (Extraction)

3Power

If a separate power cable is retained within the flowbore or clamped to the outer surface, then power transmission is achieved, but the system reliability deteriorates due to exposure to wellbore conditions

Engineering Contradiction:

Improvepower transmission capabilityVSAvoidpower cable reliability

Core Design Contradiction:

PowerVSReliability

Solution Approach 1:

The patent merges the power transmission function with the running string structure itself. Instead of having a separate power cable positioned within the flowbore or clamped to the outer surface, the running string becomes the power transmission medium, eliminating the separation between mechanical support and electrical power functions.

Inventive Principle:

Principle #5Merging (Combining)

Solution Approach 2:

The patent extracts the power transmission function from the separate power cable and integrates it into the running string. This eliminates the need for a distinct power cable component that would be positioned in vulnerable locations within or on the running string.

Inventive Principle:

Principle #2Taking out (Extraction)

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

The dual-walled coiled tubing running string enhances power transmission efficiency, reduces viscosity of transported fluids through waste heat, offers additional physical support for ESPs, and provides a more reliable and cost-effective solution compared to conventional power transmission methods.

Implementation Method 1

Electric current is transmitted along the dual-walled coiled tubing running string via skin effect

Methodology Applied

Scientific EffectSkin effect: Skin Effect

Implementation Method 2

Waste heat from power transmission can mitigate the effects of high viscosity of fluids being transported through the inner coiled tubing string to surface. The heat generated by transmission of electric power via the coiled tubing assembly will lower the viscosity of transported fluids

Methodology Applied

Scientific EffectJoule heating: Joule Heating

Data Source

PatentUS10240406B2Dual-walled running string for electric devices with power transmission through running string

Publication Date: 2019.03.26 BAKER HUGHES CO

AI summary

Arrangements for transmitting electrical operating power to a downhole electrically operated tool via a dual-walled conductive running string.