Control Line Sharing for Subsurface Safety Valves
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Solution Overview
Problem
In subsurface safety valve systems, particularly in deep water applications, there is a challenge in reducing the number of control lines while ensuring the insert safety valve operates without the need for pressurized gas chambers to offset hydrostatic pressure, due to space constraints and the risk of gas pressure loss in single line systems, and the increased cost and space requirements of dual line systems.
Innovation Solution
A system where one control line serves both the lower safety valve and the insert valve, with the landing nipple allowing the operating line of the lower safety valve to become a balance line for the insert valve, eliminating the need for additional lines and pressurized gas chambers, and allowing dual use of a single line to reduce the total line count.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If a single control line is used for the insert safety valve, then the line count is reduced, but pressurized gas chambers or other means are required to offset hydrostatic pressure
Solution Approach 1:
The patent merges the control line system of the original safety valve with the insert safety valve by routing the original control line through the landing nipple to serve as the balance line for the insert valve. This consolidation reduces the total number of control lines from three to two while eliminating the need for pressurized gas chambers in the insert valve.
Solution Approach 2:
The original control line is given dual functionality: it continues to operate the original safety valve while simultaneously serving as the balance line for the insert safety valve. The landing nipple acts as a universal connection point that enables this multi-functional use of the control line.
2Reliability
If a dual control line system is used for the insert safety valve, then hydrostatic pressure is offset without gas chambers, but space requirements increase in the crowded annular volume
Solution Approach 1:
The patent combines the balance line requirement for the insert valve with the existing control line from the original valve. By routing the original control line through the landing nipple to serve as the balance line, the system achieves dual control line functionality (operating line and balance line) without increasing the total line count, thus conserving annular volume.
3Reliability
If pressurized gas chambers are used in the insert safety valve, then hydrostatic pressure is offset, but the risk of gas pressure loss increases
Solution Approach 1:
The patent extracts and eliminates the pressurized gas chamber from the insert safety valve design. Instead of using gas pressure to offset hydrostatic pressure, the system uses hydraulic pressure from the repurposed control line, thereby removing the source of potential gas pressure loss while maintaining the hydrostatic pressure offset capability.
4Reliability
If three control lines are used (original dual line system plus insert valve line), then both valves operate without gas chambers, but the line count and cost increase
Solution Approach 1:
The patent merges the control line requirements of both valves by routing the original control line through the landing nipple to serve dual purposes. This reduces the total line count from three to two while maintaining gas chamber-free operation, as the original control line provides both operating and balance functions for the insert valve.
Solution Approach 2:
The original control line is assigned multiple functions: it operates the original safety valve and simultaneously serves as the balance line for the insert safety valve. The landing nipple enables this universal use, allowing one line to fulfill multiple roles and reducing the overall line count.
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 configuration reduces the number of control lines required, saving space and eliminating the need for pressurized gas chambers, enabling a more reliable and efficient operation of the insert valve with a lower pressure rating, while maintaining system functionality.
Implementation Method 1
A common design has a flow tube that is actuated by a hydraulic control system from a surface location
Implementation Method 2
A closure spring is provided to act against a piston that actuates the flow tube
Implementation Method 3
there are in some instances a compressed gas chamber, atmospheric chamber or other components in the safety valve that acts on the piston in the same direction as the closure spring to offset the pressure from the liquid column in the control line
Data Source
AI summary
A system involving a lower tubing mounted safety valve having one or two control lines further contains a landing nipple above for a wireline insert valve. One line that serves the lower safety valve is tied to a connection on the landing nipple for the insert valve. When the lower safety valve malfunctions the landing nipple wall is penetrated to get communication to the line coming from the lower safety valve so that such line can serve as a balance line for the insert valve. The other line from the surface to the other connection on the landing nipple serves as the operating line for the insert valve. Making one line serve a dual purpose eliminates one control line from the surface.