Hydraulic Coupler for Subsea Riser Isolation
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Solution Overview
Problem
Existing hydraulic systems for subsea equipment face contamination and interference from external fluids, particularly during the installation of tubing hangers, where drilling fluids with higher density or pressure can compromise the hydraulic control system's integrity.
Innovation Solution
A hydraulic coupler that mechanically shifts fluid supply between two sources, using a male stab member to block external contamination by isolating non-active fluid paths and ensuring fluid communication only between the second fluid source and the return port, preventing external fluids from entering the system.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If the second hydraulic fluid path is left accessible to facilitate subsea connection to the wellhead member, then ease of operation is improved, but the risk of external fluid contamination increases
Solution Approach 1:
The coupler body is pre-configured with aligned hydraulic control fluid passages and sealing surfaces before the tubing hanger is landed on the wellhead member. The sealing element is positioned in advance to automatically seal the second hydraulic fluid path when the tubing hanger makes contact with the wellhead member, eliminating the need for additional sealing operations and ensuring immediate protection against contamination upon connection.
2Stress or pressure
If drilling fluid pressure is higher than hydraulic fluid pressure in the riser, then the ability to handle high pressure environments is improved, but the risk of fluid ingress into the hydraulic system increases
Solution Approach 1:
The sealing element is designed to utilize the higher drilling fluid pressure in the riser as a beneficial force that pushes the sealing element against the sealing surface, enhancing the seal rather than compromising it. The biasing element positions the sealing element such that pressure differential, regardless of direction, forces the sealing element into tighter engagement with the sealing surface, converting the potential harmful high pressure into a beneficial sealing force.
3Reliability
If a seal is provided over the second hydraulic fluid path to prevent contamination, then reliability is improved, but the complexity of the device increases
Solution Approach 1:
The sealing element and biasing element are integrated into a single compact assembly within the coupler body, combining multiple sealing and biasing functions into one unified component. The sealing element is positioned within the coupler body such that it simultaneously seals the second hydraulic fluid path and is biased by the biasing element, eliminating the need for separate sealing mechanisms and reducing overall device complexity while maintaining reliability.
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 hydraulic coupler effectively selects between two hydraulic fluid sources, ensuring continuous positive control of downhole components while preventing contamination from external fluids, regardless of pressure differentials, thus maintaining the integrity of the hydraulic system.
Implementation Method 1
a biasing element positioned within the coupler body and in engagement with the sealing element to bias the sealing element against the coupler body
Implementation Method 2
The ingress of drilling fluids from the riser is of particular concern when the drilling fluid has a much higher density or is at a higher pressure than the hydraulic fluid in the tubing hanger and running tool
Data Source
AI summary
A hydraulic coupler adapted to select the supply of fluid from a first source or a second source. The fluid selection is achieved by mechanically shifting a fluid selector with a male stab member that also supplies the second fluid source. When shifted, the fluid selector positively blocks the first fluid source and opens a hydraulic pathway for the second fluid source. When the male stab is disengaged, the fluid selector is pressure biased by internal and external pressure to a position allowing fluid flow from the first fluid source and preventing external fluids from entering the hydraulic system. In certain embodiments the hydraulic coupler is horizontally installed in a tubing hanger providing horizontal porting for connection with a subsea christmas tree and vertical porting for connection to a running tool. The coupler prevents riser fluid contamination of the hydraulic system regardless of the differential pressure between the riser fluid and the hydraulic system.