Time Release Downhole Trigger Mechanism
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Solution Overview
Problem
Existing downhole tool activation mechanisms lack a time delay feature, leading to immediate tool setting without ensuring proper placement, which is costly and inefficient due to the need for additional strings and manual triggering.
Innovation Solution
A mechanism that responds to hydrostatic pressure by shifting a pilot piston to bypass primary seals, allowing well fluids to actuate a secondary seal set, which eventually fails, delaying the activation of the main piston to set the downhole tool, eliminating the need for an inner string and enabling precise sequencing of tool activation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If an inner string is used to manually trigger a valve for hydrostatic pressure actuation, then the downhole tool can be set at the proper depth, but the operation becomes time-consuming and expensive
Solution Approach 1:
The system uses the wellbore's existing hydrostatic pressure to automatically trigger the valve and actuate the downhole tool at the correct depth, eliminating the need for manual intervention via inner string. The hydrostatic pressure itself serves the dual purpose of both positioning indication and actuation power source.
Solution Approach 2:
The manual mechanical triggering system (inner string + sliding sleeve valve) is replaced with an automatic hydrostatic pressure-actuated system. The valve is triggered automatically when hydrostatic pressure overcomes the spring force and shear pin, eliminating the need for mechanical manual operation.
2Ease of operation
If a sliding sleeve valve is used to control hydrostatic pressure access, then the tool can be triggered, but additional strings and manual operation are required increasing cost
Solution Approach 1:
The complex sliding sleeve valve mechanism requiring manual operation is extracted and replaced with a simpler automatic trigger mechanism. The new design removes the sliding sleeve and manual operation requirements, keeping only the essential pressure-actuated valve opening function.
Solution Approach 2:
The hydrostatic pressure system serves multiple functions: it indicates proper depth positioning, provides the triggering force for the valve, and acts as the power source for the downhole tool actuation. This multi-functionality eliminates the need for separate triggering mechanisms.
3Speed
If the valve opens immediately to allow hydrostatic pressure to actuate the tool, then the tool sets quickly, but there is no delay to ensure proper placement
Solution Approach 1:
The system performs preliminary positioning by allowing the tool to be lowered to the correct depth where hydrostatic pressure naturally occurs. The valve remains closed during this positioning phase, and only opens automatically when the predetermined depth (indicated by the specific hydrostatic pressure level) is reached, ensuring proper placement before actuation.
4Adaptability or versatility
If multiple downhole tools are set sequentially, then proper sequencing is achieved, but additional strings and time are required
Solution Approach 1:
Multiple downhole tools are actuated in periodic sequence as the hydrostatic pressure progressively overcomes the trigger mechanisms of each tool in turn. Each tool has a slightly different trigger pressure threshold, causing them to activate sequentially as pressure increases with depth, achieving automated periodic actuation without additional strings.
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 allows for precise positioning and sequencing of downhole tools with built-in delay times, reducing operational costs and eliminating the need for additional strings, enabling efficient and sequential activation of multiple tools.
Implementation Method 1
A setting mechanism is made to respond to hydrostatic pressure. Upon reaching a predetermined depth corresponding to a given pressure, a pilot piston is shifted to allow well fluids to bypass a first set of piston seals and reach a second set.
Implementation Method 2
Raising the tool from the wellbore allows the spring acting on the pilot piston to seal in a bore to isolate hydrostatic pressure from the operating piston.
Data Source
AI summary
A setting mechanism is made to respond to hydrostatic pressure. Upon reaching a predetermined depth corresponding to a given pressure, a pilot piston is shifted to allow well fluids to bypass a first set of piston seals and reach a second set. A shear pin that held the pilot piston in position is broken as the hydrostatic pressure increases with greater depth attained. However, the shifting of the pilot piston does not cause the main piston in the assembly to set the downhole tool. The action of the well fluids on the secondary seal set on the pilot piston eventually fail the second seal set allowing hydrostatic pressure to bypass them and actuate the main piston that will set the downhole tool. Raising the tool from the wellbore allows the spring acting on the pilot piston to seal in a bore to isolate hydrostatic pressure from the operating piston.