Drilling Coupler Extended Pin for Bend Fatigue
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Solution Overview
Problem
The existing coupling of stator components in drilling assemblies is susceptible to stress and breakage during directional drilling, leading to delays and increased costs due to bend fatigue and reduced stability.
Innovation Solution
A reinforcement coupling with an extended portion that provides an interference fit between the pin and stator components, increasing the cross-sectional thickness and torque-carrying capacity, thereby preventing bend fatigue and enhancing stress absorption.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the stator is coupled to other components of the drill string using a conventional coupling, then the device complexity is reduced and ease of manufacture is improved, but the coupling point experiences high stress and is susceptible to breaking during directional drilling
Solution Approach 1:
The patent adds an extended portion (nose) that protrudes axially from the pin component, extending into the inner area of the box component. This dimensional extension reinforces the coupling by preventing bend fatigue and increasing stability during directional drilling operations, while maintaining a relatively simple overall structure.
Solution Approach 2:
The extended portion is specifically positioned at the critical coupling point where the pin component connects to the box component. This localized reinforcement addresses the specific stress concentration area without requiring complex modifications to the entire coupling structure, maintaining ease of manufacture while improving reliability.
2Adaptability or versatility
If the drill string is bent to achieve directional drilling, then the wellbore can be placed in contact with selected reservoir rock, but the coupling point experiences stress and bend fatigue
Solution Approach 1:
The extended portion protruding axially from the pin component into the box component's inner area creates additional structural support that prevents bend fatigue. This dimensional addition allows the coupling to withstand the stresses of directional drilling while maintaining stability.
Solution Approach 2:
The extended portion is pre-positioned to overlap with the box component before assembly, creating an interference fit that reinforces the coupling against future bending stresses. This preliminary structural arrangement prevents fatigue failure during subsequent directional drilling operations.
3Strength
If the cross-sectional thickness at the coupling point is increased to prevent breakage, then the torque-carrying capacity is increased, but the device complexity and manufacturing difficulty increase
Solution Approach 1:
The reinforcement is achieved by segmenting the pin component into distinct portions: a threaded portion for engagement and an extended portion (nose) for reinforcement. This segmentation allows the extended portion to provide additional cross-sectional thickness and torque capacity while keeping the manufacturing process relatively simple through standard machining operations.
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 solution effectively reduces failures of drilling motors and increases the torque-carrying capacity, ensuring stability during bend operations and maintaining drilling efficiency.
Implementation Method 1
The extended portion has an interference fit with the stator.
Data Source
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AI summary
A drill tool that is usable in drilling a wellbore can include a pin component and a box component. The pin component has a threaded portion and an extended portion extending axially from an end of the threaded portion. The box component is part of a stator of a downhole drilling motor. The box component is threadedly coupled to the pin component such that the extended portion of the pin component is positioned in an inner area defined by the box component to absorb stress from the threaded portion during a bend for a wellbore drilling operation.