Rotating Indexing Coupling for Precise Subsea Tree Orientation

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Solution Overview

Problem

Traditional methods for orienting subsea production trees are complex, require significant modifications to blowout preventers, and can lead to failures in hydraulic control due to shared radial seal compartments, resulting in inefficient and costly operations.

Innovation Solution

A rotating indexing coupling (RIC) assembly with a stab body and coupler body that rotates relative to the stab body, featuring hydraulic coupling elements and coiled tubes for isolated fluid communication, allowing precise orientation and hydraulic coupling with the tubing hanger.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Manufacturing precision

If traditional BOP assembly methods are used to orient the tubing hanger, then radial orientation can be achieved, but the device complexity increases and requires significant modifications to the BOP

Engineering Contradiction:
Improveradial orientation precisionVSAvoidBOP modification complexity
Core Design Contradiction:
Manufacturing precisionVSDevice complexity

Solution Approach 1:

The orientation function is segmented from the BOP assembly into a separate RIC assembly. The RIC includes a stab body with orientation features and a coupler body with rotational capability, allowing orientation to be achieved without modifying the BOP. This segmentation resolves the contradiction by maintaining orientation precision while reducing BOP complexity.

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

The RIC assembly acts as an intermediary component between the BOP and the production tree. It provides the orientation and coupling functions that were previously required through BOP modifications, thereby simplifying the BOP while maintaining the required radial orientation precision through its own integrated orientation mechanisms.

Inventive Principle:
Principle #24Intermediary (Mediator)

2Device complexity

If shared radial seal compartments are used in hydraulic control, then device complexity is reduced, but reliability decreases due to potential hydraulic failures

Engineering Contradiction:
Improvehydraulic control structureVSAvoidhydraulic control independence
Core Design Contradiction:
Device complexityVSReliability

Solution Approach 1:

The hydraulic control system is segmented into separate, isolated seal compartments within the RIC assembly. Each compartment contains its own seal (e.g., radial seals) that is independent of other compartments. This segmentation ensures that a failure in one compartment does not affect hydraulic control in other compartments, thereby improving reliability while maintaining acceptable device complexity through modular design.

Inventive Principle:
Principle #1Segmentation

3Manufacturing precision

If multiple tolerances are accounted for in traditional orientation methods, then proper orientation can be achieved, but the assembly length increases due to flow loops

Engineering Contradiction:
Improveorientation accuracyVSAvoidassembly length
Core Design Contradiction:
Manufacturing precisionVSLength of moving object

Solution Approach 1:

The RIC assembly replaces the mechanical flow loop compensation system with a precision mechanical orientation system. The stab body with keyed orientation features and the rotatable coupler body provide direct mechanical orientation that eliminates the need for long flow loops to accommodate tolerance variations. This substitution maintains orientation accuracy while significantly reducing assembly length.

Inventive Principle:
Principle #28Mechanics substitution (Replace mechanical system)

4Manufacturing precision

If traditional orientation methods are used, then radial orientation can be achieved, but ease of operation decreases due to complex installation procedures

Engineering Contradiction:
Improveradial orientationVSAvoidinstallation complexity
Core Design Contradiction:
Manufacturing precisionVSEase of operation

Solution Approach 1:

The RIC assembly incorporates self-aligning and self-orienting features that reduce the complexity of installation operations. The stab body with its orientation key and the coupler body with rotational capability allow the assembly to self-adjust to the correct orientation during installation, eliminating the need for complex external orientation procedures and improving ease of operation while maintaining radial orientation precision.

Inventive Principle:
Principle #25Self-service

Data Source

PatentEP4269746B1Rotating indexing coupling (RIC) assembly for installation and orientation of a subsea production tree
Publication Date: 2025.11.19 FMC TECHNOLOGIES INC
  • EP4269746B1 patent drawingFigure 1
  • EP4269746B1 patent drawingFigure 2~3
  • EP4269746B1 patent drawingFigure 4

AI summary

One illustrative apparatus (100) disclosed herein includes a stab body (37), at least one inlet/outlet (61) and a coupler body (35) positioned around the stab body (37), wherein the coupler body (35) is adapted to rotate relative to the stab body (37). Also included is at least one hydraulic coupling element (70) positioned on the coupler body (35) and at least one coiled tube (52) positioned around the stab body (37), the at least one coiled tube (52) being in fluid communication with the at least one first hydraulic coupling element (70) and the at least one inlet/outlet (61).