Torque-balanced wellbore cable armor layers

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Solution Overview

Problem

Typical wireline cable designs suffer from torque imbalance between armor wire layers, leading to cable stretch, deformation, and reduced strength, due to larger torque generated by the outer armor wire layer, which results in gas infiltration and damage to the cable core.

Innovation Solution

A wellbore cable design featuring a cable core surrounded by multiple armor wire layers with a predetermined percentage coverage, typically between 50% to 90%, and a polymeric material layer that bonds to the armor wires and core, achieving torque balance and enhanced durability.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Object-affected harmful factors

If larger-diameter armor wires are placed in the outer layer to provide additional protection against impact and abrasion damage, then protection capability is improved, but torque imbalance between armor wire layers worsens

Engineering Contradiction:

Improveprotection against impact and abrasion damageVSAvoidtorque imbalance between armor wire layers

Core Design Contradiction:

Object-affected harmful factorsVSStability of the object's composition

Solution Approach 1:

The patent applies asymmetry by using different armor wire diameters in different layers (smaller inner layer, larger outer layer) and different coverage percentages (inner layer at 98%, outer layer at 60-80%). This asymmetric configuration balances the torque generated by each layer, where the larger outer layer compensates for its lower coverage, achieving overall torque equilibrium while maintaining superior protection capability.

Inventive Principle:

Principle #4Asymmetry

Solution Approach 2:

The patent changes key parameters including armor wire diameter, coverage percentage, and layer configuration to resolve the contradiction. By adjusting the outer layer coverage to 60-80% (lower than the inner layer's 98%) and using larger diameter wires, the torque balance equation is satisfied while enhancing protection against impact and abrasion.

Inventive Principle:

Principle #35Parameter changes

2Strength

If outer armor wire layer carries more loads with larger pitch diameter, then strength is improved, but torque imbalance increases resulting in cable stretch and core deformation

Engineering Contradiction:

Improveload carrying capacity of outer armor layerVSAvoidtorque imbalance causing cable stretch and deformation

Core Design Contradiction:

StrengthVSStability of the object's composition

Solution Approach 1:

The patent applies the counterweight principle by configuring the armor wire layers to generate opposing torques that balance each other. The outer layer with larger diameter and 60-80% coverage generates torque in one direction, while the inner layer with smaller diameter and 98% coverage generates torque in the opposite direction, achieving equilibrium and preventing cable stretch and core deformation.

Inventive Principle:

Principle #8Anti-weight (Counterweight)

Data Source

PatentUS9959953B2Torque-balanced electrical cable

Publication Date: 2018.05.01 SCHLUMBERGER TECH CORP

AI summary

An embodiment of a wellbore cable comprises a cable core, at least a first armor wire layer comprising a plurality of strength members and surrounding the cable core, and at least a second armor wire layer comprising a plurality of strength members surrounding the first armor wire layer, the second armor wire layer covering a predetermined percentage of the circumference of the first armor wire layer to prevent torque imbalance in the cable.