Toe Valve Pressure Cycling for Casing Integrity Testing
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Solution Overview
Problem
Toe valves that require high fluid pressure to open can prematurely open during casing integrity pressure tests, potentially damaging the casing or creating leaks, and those with mechanical mechanisms for opening can be impractical in horizontal wells due to access issues.
Innovation Solution
A downhole tool with a toe valve design that includes an unlocking piston and arming sleeve, where the toe valve is unlocked by increasing fluid pressure and then opened by reducing pressure, allowing fluid communication between the tool bore and the well formation using a sequence of pressure cycles.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If high fluid pressure is applied to open the toe valve, then the toe valve opens to allow fluid communication, but the toe valve may prematurely open during casing integrity pressure tests
Solution Approach 1:
The toe valve mechanism is segmented into distinct functional components: an unlocking piston that responds to high pressure to release the arming sleeve, and a separate valve opening mechanism that responds to pressure reduction. This segmentation allows the system to distinguish between pressure testing conditions and actual toe valve opening conditions, preventing premature opening during integrity tests.
Solution Approach 2:
Instead of opening the toe valve by applying high pressure directly to the valve mechanism, the invention inverts the approach: high pressure first unlocks the arming sleeve, but the actual valve opening is triggered by reducing pressure below a threshold level. This inversion ensures the valve remains closed during high-pressure integrity testing while enabling controlled opening when pressure is reduced after testing.
2Reliability
If mechanical mechanisms are used to open the toe valve, then the valve can be controlled to open, but access becomes impractical in horizontal wells
Solution Approach 1:
The invention replaces complex mechanical opening mechanisms with a pressure-responsive system. The toe valve opens automatically in response to pressure reduction, eliminating the need for mechanical actuators, linkages, or manual intervention that would be difficult to deploy in horizontal wells. The pressure cycling method can be remotely controlled from the surface, greatly improving ease of operation.
Solution Approach 2:
The toe valve opening mechanism is actuated by hydraulic pressure cycling rather than mechanical means. The unlocking piston and arming sleeve are controlled by fluid pressure changes that can be transmitted through the wellbore from surface equipment, enabling reliable operation in horizontal wells where mechanical access is impractical.
3Reliability
If the toe valve is designed to open at high pressure, then it can remain closed during normal operation, but it cannot be safely pressure tested at high pressures
Solution Approach 1:
The toe valve system dynamically responds to pressure changes through a two-stage process: the unlocking piston activates at a first pressure threshold to release the arming sleeve, but the valve actually opens only when pressure drops below a second, lower threshold. This dynamic behavior allows the valve to remain reliably closed during high-pressure operations and integrity testing, while enabling controlled opening when pressure is reduced, thus resolving the contradiction between sealing reliability and pressure testing capability.
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
Enables safe and effective pressure testing of casing integrity without prematurely opening the toe valve, allowing for subsequent operation at lower pressures and facilitating access in various well orientations.
Implementation Method 1
The unlocking piston is adapted for actuation by a pressure at the first port to unlock the arming sleeve
Implementation Method 2
A spring is loaded against the arming sleeve and biases the arming sleeve in an axial direction towards the unlocking piston
Implementation Method 3
The valve piston is adapted for actuation by a pressure at the uncovered second port to uncover the valve port. The pressure at the uncovered second port is less than the pressure applied at the first port to unlock the arming sleeve
Data Source
AI summary
A tool includes a housing between an outer wall and an inner wall that surrounds a longitudinal tool bore. First and second axially spaced ports connect the housing to the tool bore. An unlocking piston seals across the first port and an arming sleeve seals across the second port. A Locking ring is held in place by a retaining ring and prevents the arming sleeve from sliding towards the unlocking piston to open the second port. An unlocking tool bore pressure at the first port moves the unlocking piston axially to displace the retaining ring and unlock the tool. A lower, arming tool bore pressure moves the arming sleeve in the unlocked tool to open the second port and arms the tool. An actuating tool bore pressure, which is less that the unlocking pressure, actuates a valve piston via the open second port.