Garter Spring Spacer Elements to Prevent Seal Cracking
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Solution Overview
Problem
Sealing tools, such as bridge plugs, experience internal linear cracking during the setting process due to axial pressure, which compromises the seal's ability to maintain pressure differential, particularly in the rubber volume between the outer garter spring, inner garter spring, and balls, leading to pressure leakage.
Innovation Solution
Incorporation of spacer elements, such as small springs or rods, within the gaps between the balls in the garter spring to reinforce the rubber volume and maintain ball positioning, reducing the likelihood of cracking and internal stress.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If axial pressure is applied during the setting process, then the seal expands to seal the annular gap, but internal linear cracking occurs in the rubber volume between the garter spring and balls
Solution Approach 1:
A spacer element is introduced as an intermediary component between the balls of the garter spring. This spacer element mediates the stress distribution during seal expansion, preventing direct stress concentration on the rubber volume and thereby eliminating linear cracking while maintaining sealing capability.
Solution Approach 2:
The spacer element provides beforehand cushioning by being pre-positioned between the balls to absorb and distribute axial pressure before it can concentrate on the rubber volume. This preventive measure cushions the rubber against cracking during the setting process.
2Reliability
If the seal is expanded radially to set state, then sealing is achieved, but pressure leakage occurs through cracking in the rubber volume
Solution Approach 1:
The spacer element acts as an intermediary that blocks the propagation of cracks through the rubber volume. By being positioned between the balls, it prevents pressure leakage paths from forming, thereby maintaining pressure differential without compromising sealing integrity.
3Ease of operation
If balls are spaced within the garter spring, then the seal structure is formed, but gaps between balls create stress concentration leading to cracking
Solution Approach 1:
The spacer element serves as an intermediary that fills the gaps between balls, eliminating stress concentration points while preserving the necessary ball spacing for seal structure formation. It mediates between the need for gaps (for structure) and avoidance of stress concentration (for strength).
Solution Approach 2:
The spacer element introduces local quality changes by being positioned specifically between the balls rather than uniformly throughout. This localized intervention addresses stress concentration at critical points while maintaining the overall seal structure and functionality.
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
The inclusion of spacer elements significantly reduces cracking and enhances the sealability of the seal assembly by maintaining even spacing and reinforcing the rubber volume, ensuring effective sealing against the wellbore.
Implementation Method 1
a coiled spring member (410) having an inside diameter (ID1) and an outside diameter (OD1)
Implementation Method 2
ones of spacer elements located in gaps between the plurality of spaced balls
Data Source
AI summary
Provided is a garter spring, a downhole tool and a well system. The garter spring, in one aspect, includes a coiled spring member having an inside diameter (ID1) and an outside diameter (OD1). The garter spring, in accordance with this aspect, further includes a plurality of spaced balls located within the inside diameter (ID1) of the coiled spring member, as well as ones of spacer elements located in gaps between the plurality of spaced balls.