Modular Downhole Plug Tool With Shear Pin Sequencing
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Solution Overview
Problem
Current wellbore plug assemblies require expensive electric line equipment and additional manpower for deployment and retrieval, especially in high-pressure applications, making them cost-prohibitive for many situations.
Innovation Solution
A modular wellbore plug assembly using cylindrical sealing elements made of malleable materials, shear pins of varying strengths for controlled engagement, and a knockout plug for pressure equalization, allowing deployment and retrieval with standard slickline equipment, thereby reducing costs and manpower needs.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If multi-barrier tools capable of holding extremely high pressures are used, then sealing integrity is improved, but deployment cost and manpower requirements increase significantly
Solution Approach 1:
The plug assembly is divided into multiple independent barrier sections (first barrier, second barrier, third barrier) that can be deployed sequentially. Each barrier is a self-contained sealing unit with its own mandrel and sealing elements, allowing the system to achieve high-pressure sealing integrity through multiple barriers while maintaining manageable deployment complexity by using standardized modular units
Solution Approach 2:
The patent employs nested mandrels where smaller mandrels are positioned inside larger ones (first mandrel inside second mandrel, second mandrel inside third mandrel). This nesting arrangement allows sequential deployment of multiple barriers through a single deployment mechanism, reducing the need for multiple crews and complex equipment while maintaining reliable multi-barrier sealing
2Reliability
If e-line equipment and crews are used for deployment, then high-pressure sealing capability is achieved, but upfront costs and manpower consumption increase by up to 60%
Solution Approach 1:
The plug assembly is designed with universal slickline deployment capability that can be used across multiple wellbore applications. The standardized barrier sections and coupling mechanisms allow the same equipment and procedures to be reused for different sealing requirements, reducing upfront costs by eliminating the need for specialized e-line equipment while maintaining high-pressure sealing capability through proper barrier design
Solution Approach 2:
The patent employs disposable shear pins made of relatively inexpensive materials that are designed to fail at specific pressure thresholds. These shear pins are replaced rather than repaired, and their low cost allows for multiple deployment cycles using standard slickline equipment without requiring expensive reusable high-pressure components, thereby reducing overall deployment costs while maintaining reliable sealing
3Ease of operation
If multiple mandrels with varying shear strengths are used for controlled engagement, then deployment control is improved, but device structure becomes more complex
Solution Approach 1:
Each mandrel is assigned a specific local quality in the form of a predetermined shear strength tailored to its deployment sequence. The first mandrel has shear pins designed to fail at a lower pressure threshold than the second mandrel, which in turn has pins with higher thresholds. This local differentiation in shear strength allows controlled sequential engagement of barriers without requiring complex overall mandrel structures, as each individual mandrel remains relatively simple but is optimized for its specific function in the deployment sequence
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 efficient and cost-effective deployment and retrieval of multi-barrier plug assemblies in high-pressure wellbores using standard slickline equipment, reducing upfront costs and manpower requirements while maintaining high-pressure sealing integrity.
Implementation Method 1
selecting at least two shear pins according to a desired order of engagement of at least two mandrels
Implementation Method 2
cylindrical elements made of rubber or another malleable material
Data Source
AI summary
A pressure-isolation device has a plug for isolating pressure within a wellbore. The plug can include one or more modular mandrel assemblies partially disposed within each other. Each mandrel assembly can include a sealing element and a shear pin for setting the mandrel section. Each mandrel assembly can also have a collar element, a shear sleeve, a mandrel stop element, and a back-up ring in contact with the sealing element. The plug can further include a bottom receiving element including a knockout plug. The plug assembly can include a top catch element for setting and pulling the plug.