Subsea Umbilical Multicore Cable Hydrogen Barrier
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Solution Overview
Problem
In subsea oil field operations, low voltage multicore electric cables in umbilicals are prone to hydrogen gas diffusion from seawater, leading to detrimental effects within the cables over time.
Innovation Solution
Incorporating a tubular metallic layer, preferably made of copper, around the insulated electric conductors, along with a protective polymer sheath and hydrogen absorbent materials to prevent hydrogen diffusion and circulation, and optionally using armouring wires for mechanical resistance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If a simple multicore cable construction is used, then manufacturing cost and complexity are reduced, but hydrogen gas diffusion into the cable occurs leading to detrimental effects
Solution Approach 1:
The cable incorporates a composite structure combining a metallic hydrogen barrier layer with a polymer sheath. The metallic layer (copper or aluminum) provides effective hydrogen diffusion barrier properties, while the polymer sheath provides mechanical protection and chemical resistance to seawater, creating a composite material system that addresses both protection needs
Solution Approach 2:
The cable structure implements nested protection layers: the metallic hydrogen barrier layer is positioned inside the polymer sheath, creating a nested configuration where the inner metallic layer specifically blocks hydrogen diffusion while the outer polymer layer provides general environmental protection and mechanical strength
2Reliability
If additional protective layers are added to prevent hydrogen diffusion, then reliability is improved, but device complexity and manufacturing difficulty increase
Solution Approach 1:
The protective structure applies local quality by using a metallic layer specifically where hydrogen diffusion blocking is needed (around the conductors), rather than using a thick uniform protective layer throughout. This targeted approach provides effective hydrogen protection only where the conductors are vulnerable, reducing overall complexity
Solution Approach 2:
The metallic layer serves as an intermediary barrier between the seawater environment and the electric conductors. It specifically mediates hydrogen diffusion by blocking hydrogen atoms from reaching the conductors, while allowing the cable to maintain its functional simplicity for electrical transmission
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
Significantly reduces hydrogen gas diffusion and circulation within the cables, maintaining a hydrogen-free environment and enhancing mechanical strength and electrical performance.
Implementation Method 1
The metallic layer acts as a barrier against the diffusion of hydrogen from the outside to the inside of the cable
Implementation Method 2
over an extended period of time, in some circumstances related to the presence of sea water, small quantities of hydrogen appear inside the umbilical structure, and then diffuse inside the electric cables
Data Source
AI summary
An umbilical for use in the offshore production of hydrocarbons, the umbilical comprising a plurality of functional elements contained within an outer sheath, at least one of said functional elements comprising a multicore electric cable, said multicore electric cable comprising a plurality of insulated electric conductors electrically insulated from each other and assembled together in a helical or S/Z manner, said multicore electric cable further comprising a protective polymer sheath surrounding said plurality of insulated electric conductors, said multicore electric cable further comprising a tubular metallic layer located inside said protective polymer sheath and surrounding said plurality of insulated electric conductors.