Flexible Pipe Length Adjustment for Offshore Stability

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Solution Overview

Problem

Flexible pipe systems used for transferring fluids between seabed and sea surface installations face challenges in accommodating forces and movements due to weather conditions and vessel movements, leading to potential damage from bending, contact with the seabed, or uncontrolled swinging.

Innovation Solution

A flexible pipe system with a fixed subsea structure and a sliding-S configuration, where the flexible transporting unit can vary in length between a minimum and maximum length, supported by a subsea structure that allows sliding relative to the support section, reducing the risk of damage and providing stability and control.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Adaptability or versatility

If the flexible pipe is made longer to allow vessel movement, then the adaptability to weather conditions is improved, but the risk of uncontrolled swinging and damage increases

Engineering Contradiction:

Improveadaptability to vessel movementVSAvoidrisk of uncontrolled swinging

Core Design Contradiction:

Adaptability or versatilityVSReliability

Solution Approach 1:

The flexible pipe system transitions from a static fixed configuration to a dynamic adjustable configuration. The pipe length can be varied between a first length and a second length, allowing the system to adapt to different operational conditions while maintaining control through the tensioning mechanism that prevents uncontrolled swinging.

Inventive Principle:

Principle #15Dynamics

Solution Approach 2:

The system changes the physical parameter of pipe length dynamically. By adjusting the flexible pipe between different lengths using the tensioning mechanism, the system optimizes both adaptability to vessel movement and control stability, resolving the contradiction between flexibility and reliability.

Inventive Principle:

Principle #35Parameter changes

2Stability of the object's composition

If the tensioning mechanism applies sufficient tension to prevent excess slack, then the stability of the flexible pipe is improved, but uncontrolled swinging and over bending may occur

Engineering Contradiction:

Improvestability of flexible pipeVSAvoiduncontrolled swinging and over bending

Core Design Contradiction:

Stability of the object's compositionVSObject-affected harmful factors

Solution Approach 1:

The tensioning mechanism incorporates a feedback control system that monitors the state of the flexible pipe and adjusts tension accordingly. This feedback mechanism ensures sufficient tension is applied to prevent excess slack and maintain stability, while automatically reducing tension to prevent uncontrolled swinging and over bending, thus resolving the contradiction between stability and harmful effects.

Inventive Principle:

Principle #23Feedback

Solution Approach 2:

The tensioning mechanism dynamically adjusts the tension level applied to the flexible pipe based on operational conditions. This dynamic control allows the system to maintain optimal tension that prevents slack and instability while avoiding excessive tension that would cause swinging and over bending.

Inventive Principle:

Principle #15Dynamics

3Measurement precision

If a rigid tensioning mechanism is used to control flexible pipe length, then the control precision is improved, but the device complexity and difficulty of installation increase

Engineering Contradiction:

Improvecontrol precision of pipe lengthVSAvoidcomplexity of tensioning mechanism

Core Design Contradiction:

Measurement precisionVSDevice complexity

Solution Approach 1:

The invention uses a flexible tensioning mechanism rather than a rigid one, employing flexible elements that can control pipe length while maintaining simplicity. This flexible approach provides sufficient control precision without the complexity and installation difficulties associated with rigid mechanical systems.

Inventive Principle:

Principle #30Flexible shells and thin films

Solution Approach 2:

The tensioning mechanism uses simple, easily replaceable components that are less complex than rigid mechanical systems. While individual components may have limited service life, their simplicity and ease of replacement reduce overall system complexity and installation difficulty while maintaining adequate control precision.

Inventive Principle:

Principle #27Cheap short-living objects (Disposable)

Data Source

PatentEP2576333B1A flexible pipe system

Publication Date: 2019.08.07 NAT OILWELL VARCO DENMARK

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AI summary

A flexible pipe system for transferring fluid between a seabed installation (7) and a sea surface installation (6). The flexible pipe system comprises a fixed subsea structure (2) with a support section (3) and a flexible transporting unit (1 ) with an axis along a length thereof, a sea surface end (4) and a seabed end (5) arranged with a horizontal distance and a vertical distance. The sea surface end (4) is connected to the sea surface installation (6) and the seabed end (5) is the touchdown point on the seabed of the flexible transporting unit (1 ) or the point along the flexible transporting unit (1) where it is connected to the seabed installation (7) which ever has the shorter horizontal distance to the sea surface end (4). The flexible transporting unit (1 ) is supported by the support section (3) of the fixed subsea structure (2) at a flexible pipe supporting area (1a) defining a flexible transporting unit sea surface length (1b) extending along the flexible transporting unit (1) from its sea surface end (4) to the flexible pipe supporting area (1a). At least a section of the flexible transporting unit (1) is movable along the axis with respect to the support section (3) of the fixed subsea structure (2) such that the flexible transporting unit sea surface length (1b) can very between a minimum and a maximum length.