Downhole Swivel Sub Freewheel Mechanism for Deviated Wellbore Deployment
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Solution Overview
Problem
In wellbore operations, particularly in deviated and extended reach drilling, there is a challenge in deploying strings like casing strings and liners without rotating the bottom section, which can lead to friction issues and potential damage due to insufficient downhole weight, especially when dealing with delicate tools or formations like sandstone, where sand control screens are required to prevent sand migration and equipment erosion.
Innovation Solution
A swivel sub with a freewheel mechanism that allows the upper section of the string to rotate independently of the bottom section, reducing drag and enabling controlled deployment and cementation while preventing damage to fragile elements, featuring a one-way clutch or sprag clutch for secure engagement in reverse rotation and an operable sealing system for safety and reliability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If the string is rotated during deployment to reduce friction, then the deployment efficiency is improved, but the bottom section may become damaged due to excessive torque
Solution Approach 1:
The string is divided into an upper section and a bottom section that can rotate independently relative to each other through the swivel sub mechanism. This segmentation allows the upper section to rotate for friction reduction while the bottom section remains stationary to avoid damage.
Solution Approach 2:
The swivel sub acts as an intermediary mechanism between the upper and bottom sections. It includes a freewheel mechanism that permits rotation of the upper section while preventing torque transmission to the bottom section, thus mediating between the conflicting requirements of rotation and protection.
2Reliability
If the bottom section is protected from rotation to prevent damage, then the reliability is improved, but the overall string deployment becomes difficult due to insufficient downhole weight
Solution Approach 1:
By segmenting the string into rotatable and non-rotatable sections, the upper section can be rotated to reduce friction and aid deployment, while the bottom section remains protected from rotation-induced damage.
Solution Approach 2:
The swivel sub serves as a mediator that enables rotation of the upper section to improve deployment ease while simultaneously protecting the bottom section from rotational damage through its freewheel mechanism.
3Object-affected harmful factors
If delicate tools like sand control screens are used to prevent sand migration, then the formation protection is improved, but the tools are susceptible to damage during deployment
Solution Approach 1:
The swivel sub acts as a protective intermediary that isolates delicate tools in the bottom section from rotational stresses during deployment. The freewheel mechanism prevents torque transmission, thereby protecting vulnerable tools while allowing the upper section to rotate for friction reduction.
4Length of moving object
If the string length is increased to reach deeper wellbores, then the wellbore access capability is improved, but the friction and deployment difficulty increase
Solution Approach 1:
The long string is segmented into upper and bottom sections with independent rotation capability. This allows the upper section to rotate during deployment to continuously break friction, making it feasible to deploy much longer strings into deep wellbores.
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
Facilitates the deployment of strings into deep and deviated wellbores with reduced risk of damage, enhances cement distribution and sealing efficiency, and allows for the use of delicate tools and accessories by managing torque and friction effectively, enabling longer liner lengths and improved wellbore stability.
Implementation Method 1
the swivel sub comprises a freewheel arranged such that the swivel sub allows rotation of the upper section of the string relative to the bottom section of the string upon rotation of the upper section in a first direction
Implementation Method 2
featuring a one-way clutch or sprag clutch for secure engagement in reverse rotation
Data Source
AI summary
The invention relates to a swivel sub for a string to be lowered into a wellbore and a method of operation in a wellbore, wherein such swivel sub is used and comprises: —a first end provided with connection means for connecting a bottom section of a string; —a second end provided with connection means for connecting an upper section of the string; —a first member, including the first end and a sleeve portion opposed to the first end; —a second member including the second end and comprising a section opposed to the second end and partially located within the sleeve portion; the first member and the second member being arranged to rotate relative to each other.