Wellbore Top Drive Non-threaded Connection Assembly

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Solution Overview

Problem

Existing top drive systems in wellbore drilling face issues with thread damage and fatigue, leading to costly downtime and potential injuries due to high stress and misalignment, especially as drilling depths increase, and there is a need for a more robust connection and effective sealing mechanism.

Innovation Solution

A top drive system with a non-threaded connection assembly using a load ring and load ring housing that supports the weight of connected items, allowing for easy inspection and replacement, and includes torque transmitting splines for efficient rotation transfer, reducing stress on the drive shaft and facilitating quick replacement of damaged components.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Strength

If a threaded connection is used to connect the drive shaft to the item below it, then the connection can transmit torque and support weight, but the threads are subject to high stress and fatigue damage leading to failure

Engineering Contradiction:

Improvethread strengthVSAvoidconnection reliability

Core Design Contradiction:

StrengthVSReliability

Solution Approach 1:

The patent removes the threaded connection from the drive shaft entirely. Instead of threading the drive shaft directly to the item below it, the invention extracts the threading function to a separate nut or coupling device that engages with external threads on the item, leaving the drive shaft with a smooth, non-threaded end that cannot suffer from thread fatigue or damage.

Inventive Principle:

Principle #2Taking out (Extraction)

Solution Approach 2:

The connection system is segmented into distinct components: the non-threaded drive shaft end, a separate nut or coupling device with external threads, and the item below it. This segmentation allows the threading function to be isolated in a replaceable component rather than being integral to the drive shaft itself.

Inventive Principle:

Principle #1Segmentation

2Ease of manufacture

If threads are used for connection, then torque transmission is achieved, but inspection for cracks is difficult and damage can occur

Engineering Contradiction:

Improveconnection ease of manufactureVSAvoidthread crack detection difficulty

Core Design Contradiction:

Ease of manufactureVSDifficulty of detecting and measuring

Solution Approach 1:

The threading is extracted from the drive shaft and placed in a separate nut or coupling device. This allows the drive shaft end to be smooth and easily inspectable, while the threaded portion becomes a separate component that can be independently examined or replaced.

Inventive Principle:

Principle #2Taking out (Extraction)

Solution Approach 2:

Instead of having internal threads in the drive shaft that are hard to inspect, the invention uses external threads on a separate nut or coupling device. External threads are much easier to visually inspect for cracks and damage, and can be coated with penetrant dye for enhanced detection.

Inventive Principle:

Principle #13The other way round (Inversion)

3Adaptability or versatility

If dynamic misalignment occurs between the drive shaft and drilling pipe, then additional moment stress is induced into the threaded connection, but this accelerates fatigue damage and can lead to failure

Engineering Contradiction:

Improvemisalignment accommodationVSAvoidservice life of connection

Core Design Contradiction:

Adaptability or versatilityVSDuration of action of stationary object

Solution Approach 1:

By removing the threads from the drive shaft, the invention eliminates the stress concentration points where misalignment moments would cause fatigue. The smooth bore end of the drive shaft can accommodate misalignment without inducing bending stresses in the connection interface.

Inventive Principle:

Principle #2Taking out (Extraction)

Solution Approach 2:

The invention provides a cushioning effect by using a separate nut or coupling device that can absorb or accommodate misalignment moments before they reach the drive shaft. This protective arrangement prevents the accumulation of fatigue damage in the drive shaft itself.

Inventive Principle:

Principle #11Beforehand cushioning (Prior cushioning)

4Reliability

If the drive shaft is damaged or fails, then the rig must be shut down for repair, resulting in lost income and delayed production

Engineering Contradiction:

Improvedrive shaft reliabilityVSAvoidrig downtime

Core Design Contradiction:

ReliabilityVSLoss of time

Solution Approach 1:

The connection system is segmented so that the threaded nut or coupling device is a separate, easily replaceable component from the drive shaft. If failure occurs, only the nut or coupling needs to be replaced rather than the entire drive shaft, significantly reducing repair time and rig downtime.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The invention treats the nut or coupling device as a sacrificial, easily replaceable component. These items can be designed as simpler, less expensive parts that can be quickly swapped out in the field, while the expensive drive shaft remains intact and reusable.

Inventive Principle:

Principle #27Cheap short-living objects (Disposable)

Data Source

PatentUS7419012B2Wellbore top drive systems

Publication Date: 2008.09.02 VARCO I P INC

AI summary

A drive system for wellbore operations, the drive system, in certain, but not necessarily all aspects, including a main body, a motor apparatus, a main shaft extending from the main body and rotatable by the motor, the main shaft having a top end and a bottom end, and an item, the item non-threadedly connected to the main shaft.