Landing String Retainer System for Offshore Heave Compensation
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Solution Overview
Problem
Existing heave compensation systems in oil and gas operations can fail, leading to catastrophic incidents such as severed pipe strings, which pose risks to personnel and equipment due to excessive forces, and existing safety measures like weak link systems can cause buckling or snapping of the landing string.
Innovation Solution
A retainer system comprising a housing with a safety sleeve and stop arrangement that limits relative movement between the housing and the pipe string, preventing excessive tensile forces and ejection of a severed pipe string, thereby maintaining pipe integrity and safety.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Force
If a weak link bail is used as a safety device to release tension load on the landing string, then the tensile loading is reduced to zero when activated, but the landing string is subjected to compression causing buckling damage
Solution Approach 1:
The retainer system introduces a safety sleeve as an intermediary component between the heave compensation system and the landing string. This safety sleeve acts as a mediator that limits the relative movement and prevents the landing string from being subjected to excessive compressive forces after weak link activation, thereby resolving the contradiction between tension release and compression prevention
Solution Approach 2:
The retainer system provides beforehand cushioning by pre-positioning the safety sleeve to limit the range of motion of the landing string. This preventive measure ensures that when the weak link bail activates and releases tension, the landing string cannot move freely into compression, thus cushioning against buckling damage before it occurs
2Reliability
If the heave compensators lock-up putting extra tension load on the weak link bail, then the pre-set load is reached and the weak link bail is released, but the landing string is abruptly subjected to compression causing buckling
Solution Approach 1:
The safety sleeve serves as an intermediary that mediates the abrupt transition from tension to compression. By limiting the relative movement between the housing and the pipe string, it prevents the landing string from experiencing sudden buckling when the weak link bail releases, thus maintaining stability during the activation event
Solution Approach 2:
The retainer system applies preliminary anti-action by pre-configuring the safety sleeve to oppose excessive compression movements. When the weak link bail releases and the landing string tends to move into compression, the safety sleeve immediately engages to counteract this movement, preventing buckling before it can occur
3Object-affected harmful factors
If a severed upper part of the pipe string is not restrained, then it can eject through the rotary table high up over the rig floor, but restraining mechanisms may interfere with normal operations
Solution Approach 1:
The retainer system applies local quality by providing restraint only in the critical zone where the safety sleeve can engage the pipe string. The safety sleeve is positioned to limit movement only when excessive forces are present, while allowing free movement during normal operations. This localized intervention prevents ejection without interfering with routine pipe string handling
Solution Approach 2:
The retainer system embodies dynamics by allowing the pipe string to move freely during normal operations and only engaging the safety sleeve when abnormal conditions occur. The system transitions from a non-restrictive state to a restrictive state based on the forces applied, thereby preventing ejection of severed pipe while maintaining ease of operation during standard activities
Data Source
AI summary
A retainer system, device and method are provided for retaining a severed pipe string such as a landing string suspended from a rig of a floating vessel or platform during a failure of a primary or secondary heave compensation system and prevent the severed pipe string from flying over the rig floor. The retainer system includes a retainer device including a housing mounted to a platform or vessel, the housing defining a through bore for receiving a pipe string suspended from the platform or vessel. A safety sleeve extends through the housing. A stop arrangement is mountable on the pipe string, to permit engagement between the safety sleeve and the stop arrangement in order to limit relative movement between the housing and the pipe string in order to retain a severed pipe string in an emergency situation.