Riser Joint Fluid Flow Control for Emergency Disconnect
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Solution Overview
Problem
The existing technologies face challenges in providing sufficient time for emergency disconnect in riser systems during drift off or drive off situations, especially when the heave compensator fails, leading to a limited operational window.
Innovation Solution
A joint for the riser system comprising an inner and outer pipe segment with a radially extending piston, forming a chamber with a fluid line connection that controls the relative movement by regulating fluid flow, allowing for controlled extension and tension management, including the use of burst disks and valves to regulate the flow rate and activate the Emergency Quick Disconnect Package (EQDP) effectively.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the Emergency Quick Disconnect Package is activated during drift off or drive off situations, then the floating installation can be released from the subsea installation, but the activation takes more time than is available in emergency situations
Solution Approach 1:
The joint is pre-configured with a piston and fluid chamber system that is ready to activate immediately when tension exceeds the threshold. The burst disk is pre-installed and primed to rupture at a specific pressure, initiating the extension sequence without requiring active control system intervention during the emergency event.
Solution Approach 2:
The invention uses a hydraulic system with incompressible fluid in a closed chamber to control the extension of the inner pipe segment. When the burst disk ruptures, fluid pressure differential drives the piston, which controls the extension speed through restricted fluid flow paths, providing smooth and controlled movement rather than abrupt mechanical action.
2Loss of time
If the inner pipe segment is allowed to extend rapidly to gain time for EQDP operation, then more time is available for emergency disconnect, but the tension in the riser may exceed threshold values and cause failure
Solution Approach 1:
The joint transitions from a static rigid connection to a dynamic extensible connection in response to increasing tension. The piston-controlled extension mechanism allows the joint to adapt its length dynamically during the emergency event, extending at a controlled rate that balances time gain with tension management.
Solution Approach 2:
The system changes the physical parameter of riser length in a controlled manner through piston-driven extension. By regulating fluid flow through restricted passages, the extension rate is controlled to prevent excessive tension buildup while still providing sufficient time for EQDP operation.
3Loss of time
If a fluid line connection is used to control the extension rate through regulated fluid flow, then the extension can be controlled and time gained, but the device complexity increases
Solution Approach 1:
The joint is designed to activate and control its own extension automatically through the burst disk rupture and fluid pressure differential. The system uses the existing tension force in the riser to drive the extension process, converting the harmful high tension into the driving force for controlled extension without requiring external power or control systems.
Solution Approach 2:
The inner pipe segment is nested within the outer pipe segment, with the piston and fluid chamber system contained within the annular space between them. This nested configuration allows the extension mechanism to be integrated within the existing joint structure without requiring separate external components.
4Loss of time
If the joint extends to allow more time for EQDP operation, then operational window is increased, but the riser may experience excessive movement affecting the end position relative to the wellhead
Solution Approach 1:
The fluid pressure in the chamber acts as a feedback mechanism that automatically regulates the extension process. As the inner pipe segment extends, the fluid pressure differential decreases, naturally slowing the extension rate and providing stable positioning when the chamber volume change is minimized, thereby maintaining end position accuracy.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The joint extends the operational window of the riser system by allowing controlled extension and tension management, ensuring adequate time for EQDP activation and preventing riser failure by regulating the flow of fluid through the chamber, thus enhancing safety and operational reliability.
Implementation Method 1
one of said chamber parts in an initial position of the joint is adapted to contain a mainly incompressible fluid
Implementation Method 2
the relative movement of the pipe segments is controlled by the allowed flow rate of a fluid flowing through the fluid line connection
Implementation Method 3
The burst disk will brake as a result of a pressure in the chamber part exceeding a predetermined pressure level, a threshold value
Data Source
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AI summary
The present invention regards a joint for use in a riser (1) extending between a floating installation (3) and a subsea installation (2). The joint comprises an inner pipe segment (21) and an outer pipe segments (22), arranged moveable relative each other in an axial direction and connectable to respective riser segments, forming a chamber (23) between them with a radially extending piston (24), dividing the chamber (23) in a first chamber part (25) and a second chamber part (26), wherein on of said chamber parts (25) in an initial position of the joint is adapted to contain a mainly incompressible fluid, this chamber part (25) decreasing in volume as the inner pipe segment (21) is moved relatively out of the outer pipe segment (22). According to the invention the joint is configured with a fluid line connection (30) from said one chamber part (25) to the other chamber part (26), configured such that the relative movement of the pipe segments (21, 22) is controlled by the allowed flow rate of a fluid flowing out of the chamber part (25) through the fluid line connection (30) to the other chamber part (26).