Subsurface Safety Valve Actuator for Deep Water Wells
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Solution Overview
Problem
Current subsurface safety valve systems in deep water oil or gas wells face delays and potential failures due to high pressure head and flow resistance in long control lines, which can hinder the valve's response time and reliability.
Innovation Solution
A recockable actuator within the valve body, independent of pressure head and flow line resistance, is used to open the valve, with a latching mechanism to hold the flow sleeve in place, and a disengaged actuator allows the spring to close the valve without overcoming pressure head or frictional forces.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a conventional piston-actuated valve is used in deep water wells, then the valve can be controlled from the surface, but the high pressure head and flow resistance in long control lines delay the response time and may cause failure
Solution Approach 1:
The valve actuation system is segmented into two independent parts: a surface control system that sends signals through the control line, and a subsurface actuator system that actually opens/closes the valve. The actuator includes a piston separated from the flow sleeve by a diaphragm, allowing independent operation of the actuation mechanism from the valve body. This segmentation eliminates the need for the entire control line to be filled with hydraulic fluid, reducing pressure head and flow resistance effects.
Solution Approach 2:
A diaphragm acts as an intermediary element between the piston and the flow sleeve. The diaphragm transmits force from the piston to the flow sleeve while allowing the piston to be actuated independently through the control line. This intermediary mechanism decouples the actuation system from the valve body, enabling faster response by eliminating the need to overcome pressure head and flow resistance in the control line.
2Ease of operation
If the flow sleeve is moved to open the valve using pressure from the control line, then the valve can be opened, but the spring must overcome high pressure head and flow resistance to close the valve
Solution Approach 1:
The actuator is extracted from the traditional piston-actuated configuration and repositioned within the valve body. The actuator includes a piston that can be actuated independently, and the flow sleeve is separated from the actuator by a diaphragm. This extraction allows the spring to close the valve without having to overcome pressure head or frictional forces from the control line, as the actuator handles those forces independently.
Solution Approach 2:
The system employs dynamic elements including a movable diaphragm that separates the piston from the flow sleeve, and a spring that dynamically adjusts to compress and expand forces. The diaphragm allows dynamic force transmission while maintaining separation between the actuation mechanism and the valve body, enabling the spring to operate independently of pressure head and flow resistance.
3Reliability
If a latching mechanism is added to hold the flow sleeve in place, then the valve can be securely held open, but the device complexity increases
Solution Approach 1:
The latching mechanism is merged with the actuator assembly, combining the functions of actuation and positioning into a single integrated unit. The latch mechanism engages with the flow sleeve to hold it in the open position, while the actuator can still be actuated independently through the control line. This merging reduces overall system complexity by integrating multiple functions into one assembly rather than adding separate components.
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
This design significantly reduces response time and enhances reliability by eliminating the need to overcome pressure head and flow resistance during valve closure, ensuring faster and more reliable operation.
Implementation Method 1
the spring will move the flow sleeve upwardly so as to allow the valve to close
Implementation Method 2
pressure in a control line from the surface acting on a piston in the valve which is operatively connected to a flow sleeve
Implementation Method 3
the spring must overcome the pressure head caused by the hydraulic fluid and the flow resistance due to the small diameter of the control line
Implementation Method 4
flow resistance due to the small diameter of the control line
Data Source
AI summary
A subsurface safety valve is operable to close a fluid flow path by virtue of an axially movable flow sleeve. The valve includes a recockable linear actuator and a latch mechanism so that the valve can be moved from an open to a closed position as a result of axial movement of the flow sleeve without overcoming the pressure head and frictional forces currently encountered in conventional safety valves.