Degradable Slip Inner Body for Downhole Tool Removal
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Solution Overview
Problem
Conventional downhole tools with gripping systems that use slips are difficult and costly to remove, as milling through the tool leaves large pieces that are hard to circulate out of the flowbore.
Innovation Solution
The design incorporates slip elements with an inner body portion made of degradable material that dissolves in response to a dissolving fluid, and a hardened outer contact portion that bites into the tubular member, allowing for the tool to be removed by dissolving the inner body portions with a dissolving agent, either through milling or direct contact, without the need for extensive milling.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional tool designs are used with traditional slip elements, then the gripping system provides secure anchoring, but the tool becomes difficult and costly to remove requiring extensive milling that leaves large pieces
Solution Approach 1:
The slip element is divided into two distinct portions: a hardened outer contact portion for gripping and a degradable inner body portion for structural support. This segmentation allows the inner portion to dissolve during removal while the outer portion maintains gripping function, enabling easier tool retrieval without extensive milling.
Solution Approach 2:
The material properties of the slip element are changed by using a degradable material for the inner body portion that can dissolve in wellbore fluids. This parameter change from permanent to temporary material enables the tool to be removed by dissolving the inner portion, significantly reducing removal complexity and cost.
2Ease of operation
If milling is used to remove conventional tools, then the tool can be removed from the flowbore, but large pieces are left that are difficult to circulate out
Solution Approach 1:
The inner body portion of the slip element is designed to be extracted from the system through dissolution in wellbore fluids. This extraction of the bulk material leaves only small hardened outer contact portion fragments, which are easily circulated out of the flowbore, eliminating the problem of large difficult-to-remove pieces.
Solution Approach 2:
The mechanical milling process is replaced or supplemented by a chemical dissolution process. Instead of mechanically removing large portions of the tool, the degradable inner body portion dissolves chemically in wellbore fluids, leaving only small manageable fragments that can be easily circulated out.
3Ease of manufacture
If the inner body portion is made of degradable material, then the tool can be easily removed by dissolution, but the material must be protected against premature dissolution during operation
Solution Approach 1:
The degradable inner body portion is prepared in advance with the understanding that it will dissolve at a specific time (during tool removal). The material is selected and positioned to maintain structural integrity during operation, then naturally dissolves when needed, eliminating the need for complex activation mechanisms.
Solution Approach 2:
Different portions of the slip element have different material properties: the outer contact portion uses hardened material for gripping durability, while the inner body portion uses degradable material for easy removal. This local differentiation of material quality allows the tool to maintain gripping integrity during operation while enabling easy removal afterward.
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 method enables efficient and cost-effective removal of downhole tools by dissolving the inner body portions, allowing the outer contact portions and other components to be easily circulated out of the wellbore, reducing the need for extensive milling and facilitating tool retrieval.
Implementation Method 1
the inner body portion is substantially formed of a material that is dissolvable in response to a dissolving agent
Data Source
AI summary
Slip elements for a downhole tool include an inner body portion that is substantially formed of a material that is degradable by dissolution in response to a dissolving fluid and a hardened, resilient, radially outer contact portion. The inner body portion may be formed of magnesium, aluminum or iron based powder.