Lead Barrier Tape Splice for Downhole Cable Gas Sealing

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Solution Overview

Problem

Existing power cables with continuous lead barriers face difficulties in splicing due to the absence of a suitable heat source and soldering capability, particularly in harsh downhole environments with corrosives like CO2 and H2S.

Innovation Solution

A lead-based tape with a Pb-Sn-Sb crystal structure is wrapped helically around the conductors to form a gas seal, using an adhesive to bond without heat, and additional layers are applied to ensure a desirable splice, including high modulus tape for reinforcement and armor for mechanical protection.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Object-affected harmful factors

If a continuous lead barrier is used to protect power cable conductors from corrosive gases, then gas permeation protection is improved, but splicing difficulty increases due to lack of heat source and soldering capability

Engineering Contradiction:

Improvegas permeation protectionVSAvoidsplicing difficulty

Core Design Contradiction:

Object-affected harmful factorsVSEase of repair

Solution Approach 1:

The continuous lead barrier is segmented into discrete lead tape sections that can be independently handled and applied during splicing operations. This allows the barrier to be applied in segments rather than requiring manipulation of a continuous barrier, making field splicing feasible without heat sources or soldering equipment.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The patent replaces the thermal/mechanical soldering process with a mechanical wrapping and bonding system. Lead tape is wrapped around conductors and bonded using mechanical pressure and adhesive properties rather than thermal fusion, eliminating the need for heat sources and soldering equipment in field conditions.

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

2Ease of repair

If lead based tape is wrapped helically around conductors to provide gas seal, then splicing ease is improved, but manufacturing complexity increases due to multiple layers and wrapping requirements

Engineering Contradiction:

Improvesplicing easeVSAvoidmanufacturing complexity

Core Design Contradiction:

Ease of repairVSDevice complexity

Solution Approach 1:

The lead tape application system is designed to be dynamic and adaptable, allowing the tape to be wrapped helically around conductors of various sizes and configurations. The wrapping process can be adjusted in the field to accommodate different cable geometries, making the system flexible rather than rigid despite the increased application steps.

Inventive Principle:

Principle #15Dynamics

Solution Approach 2:

The patent utilizes changes in physical parameters of the lead tape, including its adhesive properties, flexibility, and dimensional characteristics, to enable simple wrapping and bonding operations. By selecting lead tape with appropriate physical parameters, the system achieves effective sealing through straightforward wrapping rather than complex assembly procedures.

Inventive Principle:

Principle #35Parameter changes

3Reliability

If additional layers are added to ensure desirable splice seal, then gas seal reliability is improved, but application time increases

Engineering Contradiction:

Improvegas seal reliabilityVSAvoidapplication time

Core Design Contradiction:

ReliabilityVSLoss of time

Solution Approach 1:

The lead tape is pre-formed with appropriate dimensions, adhesive properties, and structural characteristics before field application. This preliminary preparation ensures that when the tape is applied during splicing operations, it can achieve reliable gas sealing in fewer steps and less time than if components were prepared or adjusted on-site.

Inventive Principle:

Principle #10Preliminary action

Solution Approach 2:

The patent employs thin, flexible lead tape that can conform to conductor shapes and be easily wrapped around cables. This flexibility allows multiple layers to be applied quickly and efficiently, reducing the time penalty associated with layered application while maintaining reliable gas sealing through the cumulative effect of multiple conforming layers.

Inventive Principle:

Principle #30Flexible shells and thin films

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 method allows for effective splicing of power cables in harsh environments without the need for a heat source or soldering, providing a sealed environment against gas permeation and mechanical protection.

Implementation Method 1

an extruded continuous lead barrier is provided around the conductors to block gas permeation

Methodology Applied

Scientific EffectGas barrier/permeation blocking: Permeation

Implementation Method 2

using an adhesive to bond without heat

Methodology Applied

Scientific EffectAdhesive bonding: Adhesive

Data Source

PatentUS12573525B2Lead alloy barrier tape splice for downhole power cable

Publication Date: 2026.03.10 SCHLUMBERGER TECH CORP

AI summary

A technique facilitates splicing of a power cable including splicing of a protective lead barrier. According to the technique, the power cable comprises conductors which form individual phases of a multi-phase conductor assembly. The conductors may be individually spliced for each phase of the multi-phase conductor assembly. Subsequently, splicing of the protective lead barrier may be performed by utilizing a lead based tape which is wrapped, e.g. helically wrapped, around the conductors. The wrapping technique provides a gas seal with respect to each individual insulated conductor within the multi-phase conductor assembly. Depending on the specifics of a given application and environment, additional layers may be added to ensure formation of a desirable splice.