Frac Plug Bottom Sub Raised Edges for Flow Back Obstruction

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Solution Overview

Problem

Existing frac plug systems face issues with flow back obstructions due to features like flow back pins, which hinder component movement and are costly and complex when using degradable balls in fracturing operations.

Innovation Solution

A frac plug system with an unobstructed internal passage, featuring a seal member and slips for engaging the wellbore wall, and a bottom sub with raised edges that catch balls during flow back without blocking the passage, enabling torque locking with subsequent plugs and preventing flow obstructions.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If a flow back pin is used to prevent obstructions, then flow back obstruction is prevented, but the internal flow-through passage is blocked and component movement is hindered

Engineering Contradiction:

Improveflow back obstruction preventionVSAvoidcomponent movement through internal passage

Core Design Contradiction:

ReliabilityVSEase of operation

Solution Approach 1:

The bottom sub is segmented into multiple discrete raised edges (typically 3-6 edges) spaced circumferentially around the internal passage. This segmentation allows fluid to flow through multiple separate paths between the edges, preventing obstruction while maintaining structural integrity for catching balls and providing torque lock.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The raised edges are positioned at specific locations circumferentially around the internal passage, creating localized obstruction points that catch balls while leaving the spaces between edges open for fluid flow. This local quality approach ensures ball containment without complete passage blockage.

Inventive Principle:

Principle #3Local quality

2Reliability

If degradable balls are used in fracturing operations, then flow back obstruction is addressed, but cost and operational complexity increase

Engineering Contradiction:

Improveflow back obstruction preventionVSAvoidoperational complexity and cost

Core Design Contradiction:

ReliabilityVSDevice complexity

Solution Approach 1:

The bottom sub's raised edges automatically catch and contain frac balls during flow back operations without requiring external tools, degradable materials, or complex operational procedures. The passive geometric feature performs the ball containment function inherently, eliminating the need for expensive and complex degradable ball systems.

Inventive Principle:

Principle #25Self-service

3Ease of manufacture

If a bottom sub with milling feature is used, then milling capability is provided, but flow back obstruction occurs due to blocked internal passage

Engineering Contradiction:

Improvemilling capabilityVSAvoidflow back performance

Core Design Contradiction:

Ease of manufactureVSReliability

Solution Approach 1:

The bottom sub integrates multiple functions into a single component: (1) milling capability through the engagement surface for bottoming out during milling operations, (2) ball containment through raised edges, (3) torque lock through engagement teeth, and (4) unobstructed fluid flow through the internal passage. This multi-functionality resolves the contradiction by providing milling features without sacrificing flow back performance.

Inventive Principle:

Principle #6Universality (Multi-functionality)

Data Source

PatentUS10458200B2Frac plug system having bottom sub geometry for improved flow back, milling and/or setting

Publication Date: 2019.10.29 SCHLUMBERGER TECH CORP

AI summary

A technique facilitates plugging of a wellbore during, for example, a fracturing operation. A frac plug is constructed with an unobstructed internal passage and comprises a seal member combined with a plurality of slips for engaging a surrounding wall, e.g. a surrounding wellbore wall. Additionally, the frac plug comprises a lower sub having raised edges arranged to catch a ball during a flow back stage without blocking flow along the unobstructed internal passage.