Subsea Well Safing System with Ejector Mechanism
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing subsea well blowout preventer systems fail to effectively manage uncontrolled well pressures and flows, leading to potential environmental and economic disasters, as seen in the Deepwater Horizon incident, due to inadequate sealing and control mechanisms.
Innovation Solution
A subsea well safing system comprising a safing assembly with a lower and upper assembly connected via a connector, featuring slips and a shear mechanism to secure and shear tubulars, and an ejector device to physically separate the upper assembly from the lower, allowing for controlled disconnection of the marine riser from the blowout preventer stack.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a blowout preventer is used to seal and control the well, then well control capability is improved, but system complexity and potential points of failure increase
Solution Approach 1:
The blowout preventer system is divided into multiple independent assemblies (lower BOP assembly, upper BOP assembly, intermediate assembly) that can function semi-independently. This segmentation allows the system to maintain well control capability while reducing the complexity of any single assembly and providing redundancy if one segment fails.
Solution Approach 2:
The system incorporates pre-positioned shear rams and ejector assemblies that are ready to activate immediately upon detecting a failure condition. The slips are pre-loaded and the shear mechanism is pre-configured to cut the tubular, eliminating the need for complex real-time decision-making during a blowout event.
2Reliability
If the blowout preventer remains connected to the marine riser during a failure, then well control is maintained, but physical damage spreads to the riser and platform
Solution Approach 1:
The ejector assembly is designed to physically separate the lower BOP assembly (which remains connected to the well) from the upper BOP assembly and marine riser. This extraction of the riser from the failure zone prevents uncontrolled flow from damaging the expensive marine riser and platform equipment while the lower assembly continues to seal the well.
Solution Approach 2:
The intermediate assembly acts as a mediator between the lower and upper BOP assemblies. It contains the shear rams that can cut the tubular connecting the assemblies, allowing controlled separation. This intermediary mechanism enables the system to sacrifice the intermediate assembly to protect the more critical well and riser components.
3Object-affected harmful factors
If the safing assembly is designed to automatically separate assemblies, then damage limitation is improved, but the mechanism complexity increases
Solution Approach 1:
The ejector assembly is designed to activate automatically upon detection of a failure condition without requiring external intervention. Sensors monitor well parameters and automatically trigger the ejector mechanism to separate the assemblies, eliminating the need for complex control systems or human decision-making during the critical separation phase.
Solution Approach 2:
The intermediate assembly is designed as a sacrificial component that can be deliberately destroyed (sheared) to achieve the safety function. By making this intermediate component relatively simple and replaceable, the system gains automatic damage limitation capability without requiring complex protective systems for the entire assembly.
Data Source
AI summary
A subsea well safing method and apparatus adapted to secure a subsea well in the event of a perceived blowout in a manner to mitigate the environmental damage and the physical damage to the subsea wellhead equipment to promote the ability to reconnect and recover control of the well. The safing assembly is adapted to connect the marine riser to the BOP stack. Pursuant to a safing sequence, the well tubular is secured in the upper and lower safing assemblies and the tubular is then sheared between the locations at which it has been secured. Subsequently, an ejection device is actuated to physically separate the upper safing assembly and connected marine riser from the lower safing assembly that is connected to the BOP stack.