Partially Removable Downhole Plug for Reduced Milling
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Solution Overview
Problem
Existing well bore packing devices, such as cast iron bridge plugs, are difficult to remove due to their design and material, requiring time-consuming and expensive milling or drilling processes when they become lodged in well tubing with bends or scale restrictions.
Innovation Solution
A downhole plug with a run-in, deployed, and released configuration, featuring a mandrel, bull nose, expandable slip, inner and outer sleeves, and an elastomeric member, which allows for controlled expansion and release from the well bore, enabling easier removal by applying forces to release coupling mechanisms and allowing the plug to descend or be removed in parts.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If a cast iron bridge plug is used to seal the well bore, then high differential pressure holding capability is achieved, but removal becomes time-consuming and expensive requiring milling or drilling
Solution Approach 1:
The plug body is divided into two main segments: an inner sleeve and an outer sleeve. The inner sleeve contains the sealing and anchoring mechanisms (elastomeric member and slip assembly), while the outer sleeve provides structural support. This segmentation allows the inner sleeve to be removed independently through the tubular, avoiding the need to mill or drill the entire plug body.
Solution Approach 2:
The inner sleeve, which contains the elastomeric member and slip assembly, is designed to be extracted and removed through the tubular after the plug has been set. A retrieval tool is used to engage the inner sleeve and pull it out through the tubular, leaving only the outer sleeve in the well bore. This extraction eliminates the need for time-consuming milling or drilling operations.
2Strength
If a cast iron bridge plug is used to seal the well bore, then high differential pressure holding capability is achieved, but removal becomes expensive requiring specialized equipment
Solution Approach 1:
The plug body is divided into two main segments: an inner sleeve and an outer sleeve. The inner sleeve contains the sealing and anchoring mechanisms (elastomeric member and slip assembly), while the outer sleeve provides structural support. This segmentation allows the inner sleeve to be removed independently through the tubular, avoiding the need to mill or drill the entire plug body.
Solution Approach 2:
The inner sleeve, which contains the elastomeric member and slip assembly, is designed to be extracted and removed through the tubular after the plug has been set. A retrieval tool is used to engage the inner sleeve and pull it out through the tubular, leaving only the outer sleeve in the well bore. This extraction eliminates the need for time-consuming milling or drilling operations.
3Strength
If the plug running diameter is within close tolerances with the tubular, then high differential pressure holding capability is achieved, but the plug can become lodged in bends or scale restrictions
Solution Approach 1:
The slip assembly is designed to be collapsible during run-in, allowing the plug to navigate through bends and scale restrictions in the tubular. Once the plug reaches the desired location and is set, the slip assembly expands to provide anchoring and sealing. This dynamic transformation enables the plug to accommodate varying tubular conditions during insertion while maintaining structural integrity during operation.
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
Facilitates efficient and cost-effective removal of the plug by reducing the amount of metal to be drilled out and simplifying the process, as the inner and outer sleeves can be separated from the mandrel, allowing the elastomeric member and slip to disengage, thus reducing the complexity and expense of the removal procedure.
Implementation Method 1
The expandable slip has an internal surface and an external surface. The external surface contains a gripping surface. The cone has a shaped engagement surface for engaging the expandable slip internal surface. When the plug is in the deployed configuration, the slip is expanded.
Implementation Method 2
An elastomeric member is disposed about the mandrel between the outer sleeve and the bull nose.
Data Source
AI summary
A downhole plug and a method of releasing a portion of the plug. The plug has a run-in configuration, a deployed configuration, and a released configuration. The plug includes a mandrel, a bull nose, and a cone and an expandable slip. The expandable slip has an external gripping surface. The plug includes an inner and outer sleeve, where the outer sleeve is concentric around the inner sleeve and the inner sleeve is concentric with the mandrel. The inner sleeve is slidable about but releasingly coupled to the mandrel. The inner sleeve is slidable about the outer sleeve but releasingly coupled to the outer sleeve in both the run-in configuration and in the deployed configuration. The inner sleeve is coupled with the mandrel in the run-in configuration and in the deployed configuration, but uncoupled and slidable about the mandrel in the released configuration.