Inner Drilling Riser Tie-Back Connector Locking Mechanism
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Solution Overview
Problem
Existing well riser systems face challenges in efficiently coupling a small diameter riser to a subsea wellhead for high-pressure fluid flow during drilling operations, requiring a reliable and secure connection that maintains hydraulic circulation and structural integrity.
Innovation Solution
The Inner Drilling Riser Tie-Back Connector (ITBC) system, which includes an inner and outer body with a locking assembly, allows the inner riser pipe to be securely locked within the subsea wellhead, providing a fluid-tight seal and withstanding high tension and compression loads, enabling efficient fluid flow and structural strength.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Stress or pressure
If a small diameter riser is used, then high pressure capacity and hydraulic circulation are improved, but coupling reliability to subsea wellhead deteriorates
Solution Approach 1:
The connector employs a nested structure where the inner body with small outer diameter (for high pressure capacity) is positioned within an outer body with larger inner diameter. The locking assembly with locking teeth engages between these nested bodies to secure the connection to the subsea wellhead, resolving the contradiction by allowing small diameter for pressure while maintaining coupling reliability through the locking mechanism.
Solution Approach 2:
The connector is divided into distinct functional segments: an inner body for high pressure fluid flow, an outer body for structural support and engagement, and a locking assembly with locking teeth for secure attachment. This segmentation allows each component to be optimized for its specific function while working together to achieve both high pressure capacity and reliable coupling.
2Productivity
If a small diameter riser is used, then hydraulic circulation efficiency is improved, but structural integrity under load deteriorates
Solution Approach 1:
The nested configuration places the small diameter inner body (optimized for hydraulic circulation) within a larger outer body (optimized for structural strength). The outer body provides the necessary structural integrity to withstand high tension and compression loads, while the inner body maintains efficient hydraulic flow, resolving the contradiction between circulation efficiency and structural strength.
Solution Approach 2:
The connector merges the functional advantages of two different diameter structures by combining them into a single integrated assembly. The inner body provides efficient hydraulic circulation with its small diameter, while the outer body provides structural strength with its larger diameter, creating a composite structure that achieves both objectives simultaneously.
3Adaptability or versatility
If a reusable connection is designed, then operational flexibility is improved, but device complexity increases
Solution Approach 1:
The locking assembly incorporates a dynamic locking mechanism with locking teeth that can engage and disengage on demand. This dynamic feature enables the connector to be reused multiple times by simply engaging or disengaging the locking teeth, providing operational flexibility while keeping the overall design relatively simple compared to permanent welded or threaded connections.
Solution Approach 2:
The locking assembly is designed to automatically engage and lock when the connector is installed, and can be easily disengaged when removal is needed. This self-service capability allows operators to quickly install and remove the connector without complex tools or procedures, enhancing operational flexibility while minimizing the complexity of the locking mechanism itself.
Data Source
AI summary
Systems and methods for coupling a platform to a subsea wellhead are provided. The systems may include a riser extending between the platform and the subsea wellhead. The systems may further include an inner drilling riser tie-back connector (“ITBC”) coupled to an inner riser and having an outer body and an inner body. The inner body is at least partially disposed within the outer body, and the inner body is translatable along a longitudinal axis of the ITBC between a first unlocked position and a second locked position. The systems may additionally include a locking mechanism for the ITBC.