Degradable Bridge Plug Slip Elements for Easy Milling Removal
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Solution Overview
Problem
Conventional bridge plug designs face difficulties in removing large pieces left after milling, which can be challenging to circulate out of the flowbore during removal.
Innovation Solution
The bridge plug features a degradable inner body portion made of dissolvable materials like magnesium powder, exposed by rupturing a phenolic molding, combined with a hardened, resilient outer contact portion with stress risers, facilitating disintegration and easy removal via milling.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If conventional bridge plug designs are used, then the plug can be set and engaged in the flowbore, but large pieces remain after milling which are difficult to circulate out
Solution Approach 1:
The slip element is divided into two distinct portions: a hardened outer contact portion for engagement and a degradable inner body portion for dissolution. This segmentation allows the plug to be removed in small, soluble fragments rather than large solid pieces, resolving the contradiction between secure engagement and easy removal.
Solution Approach 2:
The material composition of the inner body portion is changed to be chemically degradable. By using materials that can dissolve in wellbore fluids or injected chemicals, the removal process is simplified from mechanical extraction of large pieces to chemical dissolution followed by circulation of small fragments.
2Ease of operation
If the inner body portion is made of degradable material, then removal is facilitated by dissolution, but the material must be protected against premature dissolution before removal is desired
Solution Approach 1:
A protective coating is applied to the inner body portion before the plug is set in the flowbore. This preliminary protective action prevents premature dissolution during the operational phase, while allowing controlled dissolution when removal is intentionally initiated by injecting dissolving agents.
Solution Approach 2:
The protective coating acts as an intermediary barrier between the degradable inner body material and the wellbore environment. This intermediary layer maintains reliability during operation by preventing premature dissolution, while being removable or penetrable when intentional removal is desired.
3Strength
If the outer contact portion is made of hardened material for biting engagement, then secure engagement is achieved, but the material is difficult to break down into smaller parts
Solution Approach 1:
The outer contact portion is designed with discontinuities, openings, or weakened zones that segment the hardened material into smaller sections. This segmentation maintains biting engagement strength during operation while facilitating breakdown into manageable fragments during removal, resolving the contradiction between strength and disintegratability.
Solution Approach 2:
Different regions of the outer contact portion have different properties: the outer surface maintains hardened material for biting engagement, while internal regions or specific zones incorporate discontinuities or softer materials that facilitate fragmentation during removal, allowing simultaneous engagement strength and ease of disintegration.
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 removal of the bridge plug by dissolving the inner body portions with a dissolving agent, allowing the outer contact portions to break down into smaller parts, making it easier to circulate out of the wellbore.
Implementation Method 1
the inner body portion is substantially formed of a material that is dissolvable in response to a dissolving agent
Implementation Method 2
the molding of the slip ring is ruptured by the mill, which exposes the dissolvable material forming the inner body portions to wellbore fluid
Implementation Method 3
the outer contact portion includes a plurality of openings that function as stress risers
Data Source
AI summary
Slip elements for a bridge plug 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 outer contact portion includes a plurality of openings that function as stress risers. The inner body portion may be formed of magnesium powder.