Rotating Riser System for Arctic Ice Obstacle Avoidance

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Solution Overview

Problem

Conventional offshore drilling systems face challenges in arctic regions due to the presence of ice floes and icebergs, which require frequent riser disconnections to avoid damage, leading to operational inefficiencies and increased risks, especially in areas with unpredictable ice drift patterns.

Innovation Solution

The system employs a vessel with a top swivel and base swivel that allows for lateral offset and circular movement, enabling the vessel to rotate with respect to the riser and wellhead, thereby avoiding obstacles without disconnecting the riser, and includes features like negative riser slope sections and variable buoys to maintain connection and stability.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If the vessel remains stationary over the wellhead to protect the riser connection, then the riser integrity is maintained, but the vessel cannot avoid ice floes and icebergs, leading to frequent emergency disconnects

Engineering Contradiction:

Improveriser integrityVSAvoidoperational continuity

Core Design Contradiction:

ReliabilityVSProductivity

Solution Approach 1:

The patent transforms the static riser configuration into a dynamic system by introducing a rotating joint at the wellhead that allows the riser to rotate horizontally. This enables the vessel to move laterally and avoid ice obstacles while maintaining continuous riser connection, resolving the contradiction between maintaining riser integrity and avoiding ice damage through emergency disconnects

Inventive Principle:

Principle #15Dynamics

Solution Approach 2:

The patent changes the operational parameters by allowing horizontal displacement of the vessel beyond the traditional fixed position. The rotating joint enables the riser to accommodate lateral movements and rotational movements, transforming the system from a rigid fixed-position setup to a flexible position-adjustable setup, thereby enabling obstacle avoidance without disconnecting the riser

Inventive Principle:

Principle #35Parameter changes

2Adaptability or versatility

If the vessel is allowed to drift off its fixed position to avoid ice, then obstacle avoidance is improved, but emergency disconnects become necessary, increasing operational risks

Engineering Contradiction:

Improveobstacle avoidance capabilityVSAvoidoperational safety

Core Design Contradiction:

Adaptability or versatilityVSReliability

Solution Approach 1:

The rotating joint creates a dynamic connection that accommodates vessel movement while maintaining riser integrity. This allows the vessel to adapt its position to avoid ice obstacles without requiring emergency disconnects, thereby improving both obstacle avoidance capability and operational safety simultaneously

Inventive Principle:

Principle #15Dynamics

3Reliability

If the riser is disconnected frequently to avoid ice damage, then vessel and rig safety is protected, but drilling operations are interrupted, reducing productivity

Engineering Contradiction:

Improvevessel and rig safetyVSAvoiddrilling operation continuity

Core Design Contradiction:

ReliabilityVSProductivity

Solution Approach 1:

The rotating joint enables continuous drilling operations by allowing the riser to rotate and accommodate vessel movements. This eliminates the need to interrupt drilling operations for emergency disconnects, maintaining continuous useful action while protecting vessel and rig safety through controlled rotational movement rather than disconnection

Inventive Principle:

Principle #20Continuity of useful action

4Reliability

If the vessel maintains a fixed position with limited horizontal tolerance, then the riser connection is protected, but the vessel cannot navigate through icy regions, limiting operational flexibility

Engineering Contradiction:

Improveriser connection protectionVSAvoidnavigational flexibility

Core Design Contradiction:

ReliabilityVSAdaptability or versatility

Solution Approach 1:

The rotating joint transforms the fixed-position riser system into a dynamic system that can accommodate lateral and rotational movements. This enables the vessel to navigate through icy regions with navigational flexibility while the rotating joint continuously protects the riser connection through controlled rotation rather than requiring fixed position constraints

Inventive Principle:

Principle #15Dynamics

Data Source

PatentUS9546540B2System and method for obstacle avoidance during hydrocarbon operations

Publication Date: 2017.01.17 EXXONMOBIL UPSTREAM RESEARCH COMPANY(US)

AI summary

A system and method for obstacle avoidance during hydrocarbon operations utilizing a non-vertical conduit between a vessel and associated subsea equipment. The system comprises a vessel and a conduit connected to the vessel with a first rotatable apparatus which is constructed and arranged to permit the vessel to rotate with respect to the conduit. The system also comprises a second rotatable apparatus connecting the conduit to subsea equipment secured to the seafloor. The second rotatable apparatus is constructed and arranged to permit the conduit to rotate with respect to the subsea equipment.