Subsurface Safety Valve Lockout Mechanism for Hydraulic Failure
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Solution Overview
Problem
Subsurface safety valves in the oil and gas industry often fail due to damage from vibrations and extreme downhole conditions, leading to premature failure and the inability to maintain the safety valve in an open position, especially when hydraulic actuating mechanisms fail.
Innovation Solution
A safety valve with a built-in lockout feature, including a housing, a flapper, a flow tube, a lockout rod, and a lockout ratchet element, which can be locked in an open position using a lockout tool, ensuring the valve remains open even if the hydraulic actuation fails.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If a hydraulic actuating mechanism is used to control the safety valve, then the valve can be opened and closed remotely from the surface, but the control line may be severed or detached due to vibrations and extreme downhole conditions, rendering the safety valve powerless
Solution Approach 1:
The safety valve is equipped with a lockout capability that allows it to lock itself in the open position using the existing flow tube and lockout rod mechanism, without requiring external intervention or intact control lines. The system serves itself by utilizing its own components to maintain safety function when hydraulic control fails.
Solution Approach 2:
The lockout rod and ratchet element are pre-positioned within the valve body, ready to engage if needed. This beforehand preparation ensures that when control line failure occurs, the valve can immediately transition to a locked-open state without requiring additional components or external assistance.
2Reliability
If the safety valve is designed with a lockout capability, then the valve can be locked in the open position to prevent premature failure, but the device complexity increases with additional components
Solution Approach 1:
The lockout rod is integrated with the flow tube assembly, and the ratchet element is incorporated into the existing valve body structure. By merging these lockout components with the primary valve components, the design minimizes the number of separate parts while achieving the lockout function.
Solution Approach 2:
The flow tube serves dual functions: it controls valve operation during normal hydraulic actuation and also acts as a guide for the lockout rod during lockout engagement. The lockout rod similarly serves both as a locking mechanism and as a structural element within the valve assembly, reducing the need for dedicated separate components.
3Adaptability or versatility
If the control line traverses thousands of feet of borehole with turns and twists, then the valve can be reached at the proper destination, but the control line undergoes substantial vibration and damage during descent
Solution Approach 1:
The valve system becomes self-sufficient by incorporating an intrinsic lockout mechanism that does not depend on the control line. Once the valve is opened using the control line, it can maintain its open position through the lockout rod and ratchet element, eliminating continued reliance on the vulnerable control line connection.
Solution Approach 2:
The lockout components are pre-installed and positioned within the valve body, ready to engage immediately if control line failure occurs during or after traversal. This beforehand preparation compensates for the vulnerability of the control line during the traversal process.
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 solution allows for the safety valve to be permanently locked in an open position, reducing operational time to correct failures and minimizing cost increases, with a robust design that can withstand extended storage without degradation.
Implementation Method 1
a lockout ratchet element arranged within the housing and coupled to the lockout rod, the lockout ratchet element being configured to retain the lockout rod in the deployed position
Implementation Method 2
When the hydraulic pressure is removed from the control line, the spring pushes the flow tube back up, which allows the flapper to move into its closed position
Implementation Method 3
When sufficient hydraulic pressure is conveyed to the subsurface safety valve via the control line, the piston and rod assembly forces the flow tube downward
Data Source
AI summary
A safety valve includes a housing, a flapper coupled to the housing and movable between open and closed positions, and a flow tube movably disposed within the housing to retain the flapper in the open position. A lockout rod is coupled to the housing and movable between deployed and stored positions. The lockout rod is configured to retain the flow tube in an extended position when in the deployed position. A lockout ratchet element is arranged within the housing and coupled to the lockout rod. The lockout ratchet element is configured to retain the lockout rod in the deployed position.