Downhole Pressure Relief Valve Sequencing to Prevent Locked Open
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Solution Overview
Problem
Conventional downhole tester valves can inadvertently enter a 'Locked Open' position due to high friction or pressure differentials, leading to incorrect operation and potential failure in closing the valve, especially under emergency conditions, as the pressure relief valve activates before the ball valve opens, causing the tool to remain in an unintended state.
Innovation Solution
A pressure responsive downhole tool with a selectively activatable power piston pressure relief valve that remains deactivated until the ball valve is open, utilizing a vent port between annular seals around the power piston to ensure the pressure relief valve only activates when the ball valve is in the open position, preventing inadvertent 'Locked Open' positions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If the pressure relief valve is set to activate at a low pressure (e.g., 1250 psi), then the power piston can relieve pressure easily, but the ball valve may not open if friction or pressure differential exceeds this relief pressure
Solution Approach 1:
The patent introduces a preliminary action mechanism where the ball valve is opened first by applying pressure through the power piston before the pressure relief valve activates. This sequence ensures that the ball valve opening action occurs before pressure relief, preventing the scenario where pressure relief prevents ball valve opening. The preliminary opening of the ball valve establishes the correct operational state before pressure management takes over.
2Strength
If the ball valve has high friction due to wear or high pressure differential, then higher pressure is required to open the ball valve, but this may exceed the pressure relief setting and cause the tool to index to Lock Open position
Solution Approach 1:
The system performs the ball valve opening action as a preliminary step before pressure relief occurs. The power piston applies sufficient pressure to overcome ball valve friction and open it, and only after this preliminary action is complete does the pressure relief valve activate to prevent excessive pressure buildup that would cause incorrect tool positioning.
3Reliability
If the pressure relief valve activates before the ball valve opens, then the tool enters Lock Open position inadvertently, but if the pressure relief valve is set higher to allow ball valve opening, then pressure relief cannot occur when needed
Solution Approach 1:
The patent establishes a predetermined sequence where ball valve opening is the preliminary action that must occur first. Only after the ball valve is confirmed open does the pressure relief valve activate. This sequencing resolves the contradiction by ensuring correct tool positioning through preliminary ball valve opening while preserving pressure relief functionality for subsequent pressure management.
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 solution ensures the pressure relief valve only activates when the ball valve is open, preventing unintended tool positions and allowing for safe operation by ensuring the tool remains in a normal functioning state, even under high pressure conditions, thereby avoiding the need for lengthy pressure cycles to return to normal operation.
Implementation Method 1
a first pressure conducting passage for communicating a well annulus pressure with the power piston to move the power piston from the first position
Implementation Method 2
a pressure relief valve disposed along the power piston, the pressure relief valve comprising a vent port disposed between the first and second seals
Data Source
AI summary
A pressure responsive downhole tool comprises a power piston pressure relief valve that is selectively activated and deactivated to allow pressure-related operations to be conducted. The pressure relief valve will not open until the power piston is activated, which also requires the operating element (ball valve, for example) to be opened, thereby avoided situations in which the ball valve is inadvertently placed in the Lock Open position.