Two-Stage Submersible Actuator for Subsea Valve Control
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Solution Overview
Problem
Existing subsea oil exploration systems face challenges in maintaining reliable operation of blow-out preventers due to pressure drops in hydraulic fluid transmission from surface ships to wellheads, and reliance on surface-powered sources, which can lead to failures and hydrocarbon leaks.
Innovation Solution
A two-stage submersible electrohydraulic actuator that utilizes ambient sea pressure to create fluid pressure, independent of surface power sources, with a first cylinder, intensifier piston, and actuator piston, along with a pump and valves to manage fluid flow, ensuring operation even in failure scenarios.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Stress or pressure
If pressurized hydraulic fluid is transmitted from surface ship to wellhead through long pipe, then valves can be operated, but pressure drop becomes very large reducing usable pressure at sub-surface wellhead
Solution Approach 1:
The hydraulic system is segmented into two stages: an intensifier stage that generates high pressure from ambient pressure using a small-area piston, and an actuator stage that uses this high pressure to move a large-area piston. This segmentation eliminates the need for long-distance pressure transmission while achieving the required actuation force.
Solution Approach 2:
Ambient sea water pressure serves as an intermediary resource. Instead of transmitting pressure from the surface, the system uses the ambient pressure already present at depth as the input for the intensifier piston, converting it to high pressure through the small-area surface mechanism.
2Reliability
If surface-powered power sources are used to operate subsea valves, then actuation can be achieved, but system complexity and vulnerability to umbilical failure increase
Solution Approach 1:
The actuator is self-sufficient by utilizing ambient sea pressure as its power source. The intensifier piston converts ambient pressure into high pressure without requiring external power transmission, making the system independent of surface umbilicals and capable of autonomous operation.
Solution Approach 2:
The system extracts power directly from the ambient environment (sea water pressure) rather than relying on external power sources. This extraction of environmental energy eliminates the need for complex umbilical connections and surface-powered sources.
3Adaptability or versatility
If compressed spring actuators are used for subsea valve operation, then fail-safe operation can be achieved, but adaptability to different pressure conditions and valve types is limited
Solution Approach 1:
The actuator uses dynamic hydraulic pressure transmission instead of static spring compression. The hydraulic fluid allows for adjustable and variable actuation forces by controlling fluid pressure and volume, providing adaptability to different operational requirements while maintaining mechanical simplicity through the two-stage piston design.
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 actuator provides a reliable and fail-safe mechanism for operating subsea valves, reducing the risk of hydrocarbon leaks by using ambient pressure to generate fluid pressure, eliminating the need for surface umbilical connections and ensuring continuous operation.
Implementation Method 1
an intensifier piston (22) mounted in the first cylinder for sealed sliding movement therealong; the intensifier piston having a large-area surface (26) exposed to ambient pressure, and having a small-area surface (30); an intermediate chamber (35) communicating the intensifier piston small-area surface with the actuator piston large-area surface (27)
Data Source
AI summary
The present invention provides an improved two-stage actuator (20) that broadly includes: a first cylinder (21); an intensifier piston (22) mounted in the first cylinder for sealed sliding movement therealong, the intensifier piston having a large-area surface (26) exposed to ambient pressure, and having a small-area surface (30); a second cylinder (23) having an end wall (36); an actuator piston (24) mounted in the second cylinder for sealed sliding movement therealong; an actuator rod (39) connected to the actuator piston for movement therewith and having an intermediate portion sealingly penetrating the second cylinder end wall; the actuator piston having a large-area surface (27) and a small-area surface (37), an intermediate chamber (35) communicating the intensifier piston small-area surface with the actuator piston large-area surface; and an incompressible fluid in the chamber; whereby ambient pressure (i.e., the pressure of sea water at the depth at which the device is submerged) will create pressure in the intermediate chamber for urging the actuator piston to move toward the second cylinder end wall.