Degradable Mandrel Plug for Well Isolation

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Solution Overview

Problem

Current well drilling processes face challenges in reliably isolating and fracturing well holes at increasing depths, with high costs and prolonged processes due to the difficulty in removing and recovering plugs used for well drilling, especially in high-temperature, high-pressure environments.

Innovation Solution

A plug for well drilling comprising a mandrel made from a degradable material, paired rings with at least one degradable ring, and a diameter-expandable circular rubber member, which facilitates reliable isolation and fracturing by expanding to seal the well hole and degrading after use, reducing the need for costly recovery or destruction.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If conventional plugs made from non-degradable materials are used for well isolation and fracturing, then reliable isolation and fracturing can be achieved, but the cost and time required for plug removal and recovery increase significantly

Engineering Contradiction:
Improvereliability of isolation and fracturingVSAvoidtime required for plug removal
Core Design Contradiction:
ReliabilityVSLoss of time

Solution Approach 1:

The plug is designed with a mandrel made from degradable material that breaks down after serving its isolation function, eliminating the need for costly and time-consuming retrieval operations. The plug body and rings use degradable materials that decompose under downhole conditions, transforming the plug from a permanent component requiring recovery to a temporary, self-eliminating isolation device.

Inventive Principle:
Principle #27Cheap short-living objects (Disposable)

Solution Approach 2:

The plug utilizes degradable materials whose physical and chemical properties change over time under downhole conditions (temperature, pressure, chemical environment). The mandrel and rings transition from a solid, intact state during isolation to a degraded, fragmented state after fracturing, enabling automatic removal without intervention.

Inventive Principle:
Principle #35Parameter changes

2Reliability

If conventional plugs made from non-degradable materials are used for well isolation and fracturing, then reliable isolation and fracturing can be achieved, but the overall cost of the well drilling process increases

Engineering Contradiction:
Improvereliability of isolation and fracturingVSAvoidcost of plug recovery and destruction
Core Design Contradiction:
ReliabilityVSEase of manufacture

Solution Approach 1:

The plug is designed with a mandrel made from degradable material that breaks down after serving its isolation function, eliminating the need for costly and time-consuming retrieval operations. The plug body and rings use degradable materials that decompose under downhole conditions, transforming the plug from a permanent component requiring recovery to a temporary, self-eliminating isolation device.

Inventive Principle:
Principle #27Cheap short-living objects (Disposable)

Solution Approach 2:

The degradable materials in the mandrel and rings enable the plug to self-eliminate under downhole conditions without requiring external intervention for removal. The plug automatically degrades through chemical or biological processes in the subsurface environment, eliminating the need for specialized retrieval equipment and operations.

Inventive Principle:
Principle #25Self-service

3Ease of manufacture

If degradable materials are used for the mandrel and rings, then plug removal is facilitated and cost is reduced, but the structural strength and reliability during high-temperature, high-pressure fracturing may be compromised

Engineering Contradiction:
Improveease of plug removalVSAvoidstructural strength during fracturing
Core Design Contradiction:
Ease of manufactureVSStrength

Solution Approach 1:

The plug utilizes degradable materials whose physical and chemical properties change over time under downhole conditions (temperature, pressure, chemical environment). The mandrel and rings transition from a solid, intact state during isolation to a degraded, fragmented state after fracturing, enabling automatic removal without intervention.

Inventive Principle:
Principle #35Parameter changes

Solution Approach 2:

The plug structure transitions dynamically from a rigid, strength-providing configuration during isolation to a degrading, self-eliminating state after fracturing. The degradable materials maintain structural integrity when needed and automatically break down when the isolation function is complete, adapting to different operational phases.

Inventive Principle:
Principle #15Dynamics

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 solution enables efficient and cost-effective well drilling by ensuring reliable isolation and fracturing while allowing for easy degradation and removal of the plug, thereby reducing the overall cost and time required for the process.

Implementation Method 1

a mandrel (1) formed from a degradable material

Methodology Applied
Scientific EffectHydrolysis: Hydrolysis

Implementation Method 2

a mandrel (1) formed from a degradable material

Methodology Applied
Scientific EffectBiodegradation: Decomposition (biological)

Implementation Method 3

at least one diameter-expandable circular rubber member (3) placed at a position between the pair of rings (2, 2') on the outer peripheral surface existing in the orthogonal to an axial direction of the mandrel (1)

Methodology Applied
Scientific EffectElastic expansion: Elasticity

Data Source

PatentEP3006665B1Boring plug provided with mandrel formed from degradable material
Publication Date: 2019.08.21 KUREHA CORPORATION
  • EP3006665B1 patent drawingFigure 1A~2B

AI summary

A plug for well drilling process comprising: (a) a mandrel formed from a degradable material; (b) a pair of rings placed on an outer peripheral surface existing in the orthogonal to an axial direction of the mandrel, at least one of the rings being formed from a degradable material; and (c) at least one diameter-expandable circular rubber member placed at a position between the pair of rings on the outer peripheral surface existing in the orthogonal to the axial direction of the mandrel; the percentage of mass loss in the degradable material after immersion for 72 hours in water at a temperature of 150°C preferably being from 5 to 100%; and a well drilling method comprising the step of plugging well hole using the plug for well drilling process , wherein part or all of the plug for well drilling process degrades after the plugging.