Umbilical Cable Trefoil Design for Deepwater Production Efficiency
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Solution Overview
Problem
Conventional umbilical cables for deepwater oil exploration are cumbersome to produce, require lengthy splicing processes, and have high stiffness and voltage imbalances due to their triplex configuration and filling with thermoplastic materials, leading to inefficiencies in manufacturing time, cost, and flexibility.
Innovation Solution
The umbilical cable design eliminates the triplex configuration by grouping individual conductors with increased spacing and shielding, forming a trefoil helical configuration within the cable, allowing for single passage production and optimized electrical characteristics through proper sizing of the shielding cross-section, and using insulating fillers to maintain trefoil positioning.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the triplex configuration with thermoplastic filling is used, then the cable structure is mechanically stable, but the production time increases significantly due to multiple passages and splicing operations
Solution Approach 1:
The cable is divided into five independent single-core circuits instead of triplex arrangements. Each conductor is shielded individually and grouped separately, allowing them to be manufactured independently in a single continuous passage without requiring multiple assembly operations or splicing.
Solution Approach 2:
The conductors are pre-shielded individually before final assembly. This preliminary shielding action eliminates the need for post-assembly splicing operations, allowing the entire cable to be manufactured in one continuous passage through the cabling machine.
2Stability of the object's composition
If the triplex configuration with thermoplastic filling is used, then the cable maintains structural integrity, but the cable stiffness increases making it difficult to handle
Solution Approach 1:
The thermoplastic filling material is completely removed from the cable structure. Instead of filling interstitial voids with rigid thermoplastic material, the patent uses a different construction approach where individual shielded conductors are grouped together, eliminating the source of excessive stiffness while maintaining structural integrity.
3Power
If the triplex configuration is used, then the cable can transmit power to multiple pumps, but the voltage imbalance and electrical losses increase
Solution Approach 1:
Each of the five circuits is configured as a balanced three-phase system with identical electrical characteristics. The conductors within each circuit are positioned symmetrically and equidistantly, ensuring uniform electrical properties across all phases. This local symmetry in each circuit eliminates voltage imbalances and reduces electrical losses while maintaining the ability to power multiple pumps.
4Length of moving object
If multiple splicing operations are performed to achieve required cable length, then the cable can reach deepwater installations, but the manufacturing cost and time increase significantly
Solution Approach 1:
The conductors are pre-shielded individually to the full required cable length before final assembly. This preliminary shielding to complete length eliminates the need for splicing operations, allowing the entire 12 km cable to be manufactured in one continuous passage without interruptions for splicing.
Data Source
Figure 1~3
AI summary
The invention relates to an umbilical cable, particularly adequate for subsea exploration, containing two or more three-phase power supply circuits, each consisting of three conductors grouped in a trefoil configuration, each conductor comprising a metal core surrounded by an insulating sheath, each said conductor being provided with an individual shielding whose cross section is lesser, equal to or larger than that of said core. Advantageously each insulating sheath may be surrounded by a layer of semiconductor material. Filler spacers made of an insulating material, preferably polyethylene, may be used to aid in the positioning of said trefoils. Said cable provides an economy of material, an increased flexibility, a reduction of the diameter of the finished cable and a substantial decrease of manufacturing time as compared with cables produced in accordance with the known art. The invention further relates to a manufacturing method of said umbilical cable.