Welded Capillary Tubing for Corrosion-Resistant ESP Motor Leads
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Solution Overview
Problem
Existing power and motor lead cables in downhole electric submersible pumping systems fail due to degradation from corrosive well fluids and hydrogen sulfide exposure, as they are not adequately protected by lead-based sheathing, which is also toxic and costly.
Innovation Solution
A motor lead cable design featuring an insulated conductor encased in a capillary tube with a continuous seam, formed by approximating and welding the open ends of the capillary tube around the conductor, providing enhanced protection against corrosive environments and eliminating the need for lead-based sheathing.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If lead-based sheathing is used to protect conductors, then protection against corrosion is improved, but toxicity and cost increase
Solution Approach 1:
The patent changes the material parameter from lead to stainless steel, transforming the protective sheathing from toxic to non-toxic while maintaining corrosion resistance. This material substitution resolves the contradiction by eliminating harmful properties while preserving protective functionality.
Solution Approach 2:
The patent employs a composite structure with multiple protective layers including stainless steel capillary tubing, corrosion-resistant insulation layers, and protective jackets. This composite approach provides enhanced corrosion protection without relying on toxic lead materials.
2Reliability
If conventional seamless extruded capillary tubing is used, then protection against corrosive compounds is improved, but manufacturing complexity and cost increase
Solution Approach 1:
The patent divides the capillary tubing into segments that are formed separately and then joined together using welding or other joining methods. This segmentation allows for easier manufacturing of long-length tubing while maintaining the protective benefits of stainless steel construction.
Solution Approach 2:
The patent introduces joining mechanisms (welding, brazing, or mechanical connectors) as intermediaries to connect separate tubing segments. This intermediary approach enables the assembly of long protective conduits from manageable sections, reducing manufacturing complexity.
3Reliability
If lead-based sheathing is used, then protection against H2S is improved, but weight and handling costs increase
Solution Approach 1:
The patent changes the material density parameter by substituting heavy lead with lighter stainless steel. This material parameter change reduces the weight of protective sheathing while maintaining H2S resistance, thereby resolving the contradiction between protection and weight.
4Reliability
If capillary tubing is used for motor lead cables, then protection against corrosive environments is improved, but the frictional interface prevents encapsulation of longer conductors
Solution Approach 1:
The patent segments the capillary tubing into manageable sections that can be assembled in sequence along the conductor length. This segmentation allows the tubing to accommodate longer conductors by joining multiple sections together, overcoming the friction limitation of single-piece extruded tubing.
Solution Approach 2:
The patent applies preliminary lubrication or surface treatment to the capillary tubing interior before conductor insertion. This preliminary action reduces friction between the conductor insulation and tubing wall, enabling successful encapsulation of longer conductors within the protective tubing.
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 solution effectively prevents corrosion and electrical malfunctions, ensuring the reliability and longevity of downhole equipment while reducing health and safety risks and manufacturing costs.
Implementation Method 1
welding the sides of the capillary tube together to form a closed capillary tube around the insulated conductor
Data Source
AI summary
A method for manufacturing a motor lead cable includes the steps of forming one or more motor leads and placing external armor around the one or motor leads. The step of forming each of the one or more motor leads includes providing an insulated conductor, providing an open capillary tube that has opposing sides that have not been joined together, placing the insulated conductor inside the unclosed capillary tube, approximating the sides of the unclosed capillary tube around the insulated conductor, and welding the sides of the capillary tube together to form a closed capillary tube around the insulated conductor.