Wellbore Conductive Cable Jacket to Limit Insulation Thermal Expansion
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Solution Overview
Problem
Conventional conductive cables used for powering and communicating with electrical submersible pumps (ESPs) in hydrocarbon wells lack reliability due to premature electrical failures caused by partial discharge, especially in high-temperature environments.
Innovation Solution
A cable design featuring a PEEK core jacket to provide compression and limit thermal expansion of an underlying elastomer insulation, reducing partial electrical discharge and enhancing mechanical protection, with a polyimide film and Ethylene Propylene Diene Monomer (EPDM) insulation for improved electrical reliability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional PFA insulation is used in the cable, then the cable structure is simple, but the insulation resistance is low leading to premature electrical failures
Solution Approach 1:
The patent applies composite materials by combining multiple insulation layers (PFA inner layer, EPDM middle layer, and polyimide outer layer) with different properties. Each layer serves a specific function: PFA provides basic insulation, EPDM provides mechanical protection and flexibility, and polyimide provides heat resistance. This composite structure resolves the contradiction by achieving superior electrical reliability through material combination rather than relying on a single material, thus improving insulation resistance and preventing premature electrical failures while maintaining reasonable structural complexity.
Solution Approach 2:
The patent applies local quality by assigning different material properties to different layers of the cable insulation. The inner PFA layer provides electrical insulation, the middle EPDM layer provides mechanical strength and flexibility, and the outer polyimide layer provides thermal resistance. This localized optimization of material properties throughout the cable structure resolves the contradiction by ensuring each region of the cable has the specific qualities needed for its function, thereby achieving high electrical reliability without excessive overall complexity.
2Temperature
If the cable is designed for high-temperature environments, then the cable can operate in elevated temperatures, but thermal expansion of the elastomer insulation causes reliability issues
Solution Approach 1:
The patent applies parameter changes by modifying the thermal expansion characteristics of the cable structure through the multi-layer design. The combination of PFA, EPDM, and polyimide layers creates a structure where the thermal expansion parameters are controlled and balanced across layers, preventing excessive expansion that would compromise reliability. The polyimide layer specifically counteracts thermal expansion effects, allowing the cable to operate reliably at elevated temperatures.
Solution Approach 2:
The patent uses composite materials to resolve thermal expansion issues. The multi-layer composite structure (PFA-EPDM-polyimide) is designed so that the different materials compensate for each other's thermal expansion characteristics. The polyimide layer, with its superior heat resistance and controlled expansion properties, balances the thermal behavior of the elastomer layers, maintaining cable reliability in high-temperature environments.
3Reliability
If conventional cable design is used, then manufacturing is simple, but partial electrical discharge occurs leading to premature failure
Solution Approach 1:
The patent applies composite materials to eliminate partial electrical discharge. The multi-layer insulation structure (PFA, EPDM, and polyimide) creates multiple barriers to electrical discharge, with each layer providing different electrical properties. This composite approach prevents partial discharge by distributing electrical stress across multiple interfaces and material types, thereby extending cable lifespan and preventing premature failure.
Solution Approach 2:
The patent applies beforehand cushioning by incorporating the polyimide layer specifically to prevent future electrical discharge issues. This layer acts as a preventive measure against partial discharge that would otherwise occur in high-temperature environments, cushioning the cable structure against electrical degradation before it can cause failure. The manufacturing complexity increase is justified by this preventive protection.
4Reliability
If elastomer insulation is used to improve electrical properties, then insulation resistance improves, but thermal expansion at high temperatures compromises reliability
Solution Approach 1:
The patent applies local quality by placing the polyimide layer specifically around the areas most susceptible to thermal expansion effects. The elastomer insulation (EPDM) provides excellent electrical properties and flexibility, while the polyimide layer provides thermal stability where needed. This localized application of different material qualities resolves the contradiction by allowing the elastomer to maintain electrical performance while the polyimide counteracts thermal expansion in critical regions.
Solution Approach 2:
The patent uses composite materials to combine the electrical advantages of elastomer with the thermal stability of polyimide. The EPDM layer provides high insulation resistance and flexibility, while the polyimide layer provides thermal resistance and controlled expansion. This composite structure resolves the contradiction by integrating the complementary properties of both materials, achieving both excellent electrical insulation performance and thermal stability.
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 cable design significantly increases the reliability and usable lifespan of metal encapsulated motor lead extension cables, reducing partial discharge and improving assembly, packaging, handling, and installation processes.
Implementation Method 1
The PEEK jacket may provide compression to the elastic insulation to mitigate partial electrical discharge that may exist
Implementation Method 2
the elastic insulation may have a reduced thickness to limit thermal expansion that may occur in response to the elevated temperatures
Data Source
AI summary
A cable comprising: an electrical conductor; an elastic insulation positioned around the electrical conductor; and a nonconductive jacket positioned around the elastic insulation, wherein the nonconductive jacket is to provide containment of the elastic insulation to limit thermal expansion of the elastic insulation.