Subterranean Wellbore Plug Assembly Radial Expansion

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Solution Overview

Problem

Conventional plugs used in subterranean wellbores for hydraulic fracturing operations are often large and complex, leading to inadequate engagement with the wellbore wall, which can result in poor sealing and subsequent frustration of high-pressure operations.

Innovation Solution

A plug assembly with a reduced number of components, featuring a ball seat, seal sub, and slip sub with tapered surfaces and radially expanding fingers, which securely engages with the wellbore wall through axial advancement and radial expansion, enhancing sealing efficacy under high pressure.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If conventional plugs are used with multiple components, then the plug can provide sealing function, but the plug becomes large and complex leading to inadequate engagement with wellbore wall

Engineering Contradiction:

Improvesealing qualityVSAvoidplug structure complexity

Core Design Contradiction:

ReliabilityVSDevice complexity

Solution Approach 1:

The patent combines multiple plug components (seal elements, slips, and engagement features) into a single integrated plug structure. This merging eliminates the need for separate components while maintaining both sealing functionality and adequate wellbore wall engagement, directly resolving the contradiction between reliability and device complexity.

Inventive Principle:

Principle #5Merging (Combining)

2Reliability

If conventional plugs are used with multiple components, then the plug can provide sealing function, but the plug becomes large leading to inadequate engagement with wellbore wall

Engineering Contradiction:

Improvesealing qualityVSAvoidplug length

Core Design Contradiction:

ReliabilityVSLength of stationary object

Solution Approach 1:

The patent merges seal elements and engagement features into a compact integrated structure, reducing the overall plug length while maintaining adequate engagement with the wellbore wall. This allows the plug to achieve reliable sealing without the excessive length associated with multi-component conventional plugs.

Inventive Principle:

Principle #5Merging (Combining)

3Ease of manufacture

If conventional plugs are used, then the plug can be removed by milling or cutting, but this removal process is time-consuming and complex

Engineering Contradiction:

Improveplug removal processVSAvoidremoval time

Core Design Contradiction:

Ease of manufactureVSLoss of time

Solution Approach 1:

The patent employs dissolvable materials for the plug structure that can dissolve in wellbore fluids over time, eliminating the need for mechanical removal processes like milling or cutting. This disposable approach significantly reduces removal time and operational complexity, directly addressing the contradiction between ease of manufacture and time loss.

Inventive Principle:

Principle #27Cheap short-living objects (Disposable)

4Ease of manufacture

If dissolvable materials are used for plug removal, then the removal process is simplified, but the plug material selection is limited

Engineering Contradiction:

Improveremoval process simplicityVSAvoidmaterial selection flexibility

Core Design Contradiction:

Ease of manufactureVSAdaptability or versatility

Solution Approach 1:

The patent utilizes composite material construction where dissolvable materials are combined with non-dissolvable components (such as metal slips or structural elements). This composite approach maintains the simplicity of dissolution-based removal while expanding material selection flexibility to include various dissolvable polymers, alloys, and composite formulations with different dissolution rates and mechanical properties.

Inventive Principle:

Principle #40Composite materials

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 plug assembly maintains a higher quality seal during hydraulic fracturing operations and facilitates easier removal by reducing the number of components and utilizing dissolvable materials for post-operation clearance.

Implementation Method 1

The seal sub is configured to be at least partially inserted within the slip sub so that the tapered outer surface engages with the tapered inner surface, and an axial advance of the tapered inner surface within the tapered outer surface is configured to radially expand the fingers of the slip sub

Methodology Applied

Scientific EffectTapered surface engagement: Wedge

Implementation Method 2

Axial advance of the ball seat into the seal sub is configured to radially expand the fingers of the seal sub and the sealing element

Methodology Applied

Scientific EffectAxial advancement to radial expansion: Wedge

Data Source

PatentUS11002104B2Plug assemblies for a subterranean wellbore

Publication Date: 2021.05.11 NAT OILWELL VARCO LP

AI summary

Plug assemblies for plugging a wellbore tubular and methods relating thereto are disclosed. In an embodiment, the plug assembly includes a central axis and a seal sub including a plurality of axially extending fingers and a tapered outer surface. In addition, the plug assembly includes a sealing element coupled to the axially extending fingers of the seal sub. Further, the plug assembly includes a slip sub including a tapered inner surface, and a plurality of axially extending fingers. The fingers of the slip sub each include one or more teeth. The seal sub is configured to be at least partially inserted within the slip sub so that the tapered outer surface engages with the tapered inner surface, and axial advance of the tapered inner surface within the tapered outer surface is to radially expand the fingers of the slip sub to engage with an inner surface of the tubular.