Stacked Piston Safety Valve Redundant Hydraulic Actuation
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Solution Overview
Problem
Subsurface safety valves in the oil and gas industry face failures due to control line damage and hydraulic actuating mechanism failures, leading to potential uncontrolled releases of reservoir fluids, necessitating redundant operators or systems.
Innovation Solution
A safety valve design with two independent hydraulic control lines and piston assemblies, allowing for continuous operation even if one control line fails, with a transition member and valve closure device to manage fluid flow, ensuring the valve can switch between redundant systems without ceasing production.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a single hydraulic control line is used to actuate the safety valve, then the device complexity is reduced, but the reliability decreases due to potential control line damage or mechanical failures
Solution Approach 1:
The control system is segmented into two independent control lines (first and second control lines) that can independently actuate the safety valve. This segmentation allows the system to maintain reliability even if one control line fails, as the other can still perform the actuation function.
Solution Approach 2:
The patent implements preliminary redundancy by providing a second piston assembly and control line before any failure occurs. This preliminary action ensures that if the first control line or piston assembly fails, the second is already in place to take over without requiring additional activation systems or complex switching mechanisms.
2Reliability
If redundant control lines and piston assemblies are added to prevent failures, then the reliability improves, but the device complexity increases
Solution Approach 1:
The first and second piston assemblies are merged within a single common piston bore, sharing the same hydraulic fluid pathway and structural housing. This merging approach reduces overall device complexity by eliminating the need for separate bores and reducing the number of external components, while still maintaining the redundancy benefit of having two independent actuation paths.
Solution Approach 2:
The common piston bore serves multiple functions: it houses both the first and second piston assemblies, provides a shared hydraulic fluid pathway for both control lines, and enables either piston to independently actuate the safety valve. This multi-functionality reduces the need for additional dedicated structures, thereby reducing overall system complexity.
3Reliability
If a single piston assembly is used to actuate the flow tube, then the device complexity is minimized, but the reliability decreases due to potential mechanical failures from seal wear and vibration
Solution Approach 1:
The hydraulic actuating mechanism is segmented into two separate piston assemblies (first and second piston assemblies) that can independently actuate the flow tube. This segmentation provides redundancy against mechanical failures from seal wear and vibration, as one functional piston assembly can compensate for the other if it fails.
Solution Approach 2:
The patent implements preliminary redundancy by providing a second piston assembly before any mechanical failure occurs. This ensures that if the first piston assembly fails due to seal wear or vibration, the second is already in place to take over the actuation function without requiring complex switching systems.
4Length of stationary object
If control lines traverse thousands of feet of production tubulars with turns and twists, then the safety valve can be positioned deeper in the well, but the control lines are more susceptible to vibration and damage
Solution Approach 1:
The patent implements preliminary redundancy by providing a second control line and piston assembly before any control line damage occurs during descent through the production tubulars. This ensures that if the first control line is severed or damaged due to vibration from turns and twists, the second is already in place to take over without requiring additional activation systems.
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 design ensures continuous operation of the safety valve by providing redundant systems that can switch without additional activation systems, minimizing part count and maintaining production, even in the event of control line or mechanical failures, thereby preventing uncontrolled releases.
Implementation Method 1
the first and second control lines are independent from each other to independently convey hydraulic fluid pressure to the piston bore
Data Source
Figure 1
Figure 2A~2B
Figure 2C~3A
AI summary
Disclosed is a safety valve with redundant operators or systems. One safety valve includes a piston bore in fluid communication with a first control line via first control line port and a second control line via a second control line port, the first and second control lines conveying hydraulic fluid pressure to the piston bore. First and second piston assemblies are movably arranged within the piston bore and the second piston assembly includes a transition member coupled thereto. A flow tube is arranged adjacent the transition member and moves axially within a flow passage defined in the safety valve in response to the movement of the transition member, A valve closure device moves between an open position and a closed position restricts fluid flow through the flow- passage when in the closed position, the flow tube being adapted to shift the valve closure device between open and closed positions.