Pivoting Spear Head Assembly for Drill String Engagement

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Solution Overview

Problem

Current head assemblies for tripping apparatuses through drill strings face challenges in securely engaging and disengaging within the drill string, particularly in preventing back-pushing by advancing core samples and ensuring reliable retrieval mechanisms.

Innovation Solution

The spear head assembly features a pivotally coupled spear point with a biased sleeve that can move axially and pivot between central and offset positions, along with a detent mechanism for holding positions, and a latching system with bias mechanisms and latch dogs that engage and release from latching members within the drill string.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If the spear point is fixed in position, then the structure is simple, but the alignment with overshots and latching mechanisms is unreliable

Engineering Contradiction:

Improvealignment reliabilityVSAvoidspear point mechanism complexity

Core Design Contradiction:

ReliabilityVSDevice complexity

Solution Approach 1:

The spear point is made dynamically adjustable through a pivot mechanism that allows it to rotate between a central position and offset positions. This enables the spear point to adapt its orientation to engage with overshots and latching mechanisms at different locations within the drill string, thereby improving alignment reliability without requiring multiple separate components

Inventive Principle:

Principle #15Dynamics

Solution Approach 2:

The spear point mechanism is divided into separable functional elements: the spear point itself, the pivot axis, the biasing mechanism, and the detent mechanism. This segmentation allows each component to perform its specific function independently while maintaining overall system simplicity. The modular design facilitates easier manufacturing and assembly compared to a fully integrated fixed structure

Inventive Principle:

Principle #1Segmentation

2Reliability

If the spear point is constrained to prevent movement, then the structure is stable, but the risk of jamming increases

Engineering Contradiction:

Improveoperation reliabilityVSAvoidjamming risk

Core Design Contradiction:

ReliabilityVSObject-affected harmful factors

Solution Approach 1:

The spear point is designed with controlled mobility through the pivot mechanism, allowing it to dynamically adjust its position and orientation during operation. This controlled movement prevents the spear point from becoming jammed in fixed positions, as it can rotate to accommodate variations in the drill string geometry and engagement conditions, thereby reducing jamming risk while maintaining operational reliability

Inventive Principle:

Principle #15Dynamics

Solution Approach 2:

The detent mechanism provides pre-positioning stability by holding the spear point in predetermined central and offset positions. This beforehand cushioning ensures that the spear point is properly positioned before engagement occurs, reducing the likelihood of improper alignment that could lead to jamming during operation

Inventive Principle:

Principle #11Beforehand cushioning (Prior cushioning)

3Strength

If the latching system engages firmly, then the head assembly is securely held, but the retrieval mechanism becomes less reliable

Engineering Contradiction:

Improvelatching strengthVSAvoidretrieval reliability

Core Design Contradiction:

StrengthVSReliability

Solution Approach 1:

The latching system employs movable latch dogs that can dynamically transition between engaged and disengaged states. During lowering operations, the latch dogs engage firmly with the drill string to provide strong holding force. During retrieval, the same latch dogs can be actuated to disengage, allowing the head assembly to be pulled back through the drill string. This dynamic capability resolves the contradiction between strong engagement and reliable retrieval

Inventive Principle:

Principle #15Dynamics

Solution Approach 2:

The latching mechanism is designed so that the same structural elements that provide strong engagement (latch dogs extending outward) are inverted during retrieval to provide smooth passage (latch dogs retracted inward). This inversion principle allows the system to achieve both strong holding during operation and easy retrieval when needed

Inventive Principle:

Principle #13The other way round (Inversion)

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 design enhances the secure engagement and retrieval of the head assembly by allowing axial and rotational movement of the spear point, ensuring proper alignment with overshots and latching mechanisms, while minimizing the risk of jamming and facilitating smooth operation through the drill string.

Implementation Method 1

the head assembly travels by action of gravity down the drill string

Methodology Applied

Scientific EffectGravity: Gravitation

Implementation Method 2

a sleeve having a central axis, the spear point being biased in a direction toward a proximal end of the sleeve

Methodology Applied

Scientific EffectElastic bias: Spring

Data Source

PatentEP3358125B1Head assembly

Publication Date: 2019.10.16 REFLEX INSTRUMENTS ASIA PACIFIC PTY LTD

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AI summary

A spear head assembly (12) is provided which comprises a spear point (16) having a proximal end (18) pivotally coupled about a pivot axis (20) and a sleeve (22) that is biased in a direction toward a pointed end (24) of the spear point (16). The sleeve (22) is coupled with the spear point (16) so that the spear point (16) and the pivot axis (20) can move axially relative to the sleeve (22). The spear head assembly (12) enables a head assembly (10) to be coupled to an overshot to enable tripping through a drill string.