Reverse Circulation Overshot Brake Assembly for Safe Retrieval

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Solution Overview

Problem

Conventional reverse circulation overshot systems lack feedback indicating successful coupling to an overshot catcher, and the coupled pair can get stuck in the drill string, posing safety hazards due to the risk of fluid release when dislodged.

Innovation Solution

A drill string sub with a plug assembly that includes a proximal and distal subassembly, featuring a brake apparatus to inhibit unwanted discharge of the overshot and a mechanism to provide coupling feedback through pressure changes.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If drill rods are sequentially removed to retrieve a stuck overshot, then the overshot can be recovered, but the coupled pair may be undesirably released from the drill string posing a safety hazard

Engineering Contradiction:

Improvesafe retrieval of overshotVSAvoidunwanted discharge of overshot

Core Design Contradiction:

ReliabilityVSObject-affected harmful factors

Solution Approach 1:

The brake apparatus is activated before removing drill rods to prevent the overshot from being discharged. The brake applies a counteracting force to hold the overshot in place, counterbalancing the force that would otherwise cause unwanted discharge when drill rods are removed.

Inventive Principle:

Principle #9Preliminary anti-action

Solution Approach 2:

The brake apparatus is engaged in advance before the retrieval process begins. This preliminary action ensures that the overshot is secured and cannot be accidentally discharged when drill rods are subsequently removed.

Inventive Principle:

Principle #10Preliminary action

2Reliability

If a brake apparatus is added to prevent unwanted discharge, then safety is improved, but device complexity increases

Engineering Contradiction:

Improvesafety during retrievalVSAvoidcomplexity of drill string sub

Core Design Contradiction:

ReliabilityVSDevice complexity

Solution Approach 1:

The brake apparatus is integrated into the drill string sub assembly, merging the braking function with the existing drill string components. This combination reduces overall system complexity compared to having a separate brake system.

Inventive Principle:

Principle #5Merging (Combining)

Solution Approach 2:

The brake apparatus is designed to be activated and deactivated through the existing operational procedures of the drilling system. The brake engages automatically when drill rods are removed and can be released using the existing drill string operations, eliminating the need for separate control mechanisms.

Inventive Principle:

Principle #25Self-service

3Object-affected harmful factors

If a plug assembly with brake apparatus is used to inhibit proximal movement, then overshot discharge is prevented, but the system complexity increases

Engineering Contradiction:

Improveinhibition of proximal movementVSAvoidcomplexity of plug assembly

Core Design Contradiction:

Object-affected harmful factorsVSDevice complexity

Solution Approach 1:

The plug assembly is divided into functional segments: a sealing portion that prevents fluid leakage and a braking portion that prevents proximal movement. This segmentation allows each component to perform its specific function efficiently while keeping the overall design manageable.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The plug assembly serves multiple functions: it seals the annular space around the overshot, prevents proximal movement through the brake apparatus, and can be pumped into and out of the drill string. This multi-functionality reduces the need for separate devices for each task.

Inventive Principle:

Principle #6Universality (Multi-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

Ensures safe retrieval of the overshot by preventing unintended discharge and providing real-time feedback on coupling, reducing safety risks during up-hole drilling operations.

Implementation Method 1

A biasing element can be configured to bias the distal subassembly distally to a first position

Methodology Applied

Scientific EffectElasticity: Elasticity

Implementation Method 2

The distal subassembly can comprise a seal that is configured to bias against the inner surface of the drill string sub to inhibit fluid travel

Methodology Applied

Scientific EffectFriction: Friction

Implementation Method 3

a mechanism to provide coupling feedback through pressure changes

Methodology Applied

Scientific EffectPressure Gradient: Pressure Gradient

Data Source

PatentEP4237656B1Apparatuses and methods for use with reverse circulation overshot systems

Publication Date: 2025.10.08 BOART LONGYEAR CO

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AI summary

A system can comprise a drill string sub that is configured to couple to a drill rod of a drill string, wherein the drill string sub defines a shoulder and at least one through hole. A plug assembly can be receivable with a bore of the drill. The plug assembly can be releasably coupled to the drill string sub. When decoupled from the drill string, the plug assembly can be configured to be pumped into the drill string. The plug assembly can comprise a distal subassembly that defines a receiver that is configured engage a reverse circulation overshot. A proximal subassembly can be coupled to the distal subassembly. The proximal subassembly can comprise a brake apparatus that is configured to inhibit proximal movement of the plug assembly