Subsea Well Suspension With Sequential Frangible Tubing Plugs
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Solution Overview
Problem
Existing methods for temporarily sealing hydrocarbon wells during completion and prior to stimulation are costly, time-consuming, and prone to errors, particularly with the use of single glass plugs that require precise pressure sequences and risk incorrect activation.
Innovation Solution
Implementing a tubing string with pre-installed upper and lower frangible plugs having selectively closable bypass channels, controlled by predetermined pressure pulse sequences, allowing sequential and precise activation for sealing and unsealing, eliminating the need for wireline operations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If wireline techniques are used to set temporary plugs, then the well can be sealed temporarily, but the procedure is costly, time-consuming (up to a day), and requires specialized vessels
Solution Approach 1:
The patent employs disposable glass plugs that are installed once and then shattered to open the well. These single-use plugs eliminate the need for complex wireline operations to set and remove temporary plugs, significantly reducing operational time and cost while maintaining sealing reliability during the suspension period
Solution Approach 2:
The invention extracts the complex wireline intervention vessel and procedure from the well sealing process by using pre-installed glass plugs that can be shattered in-place. This removes the disturbing element (wireline operations) and replaces it with a simpler, more efficient method
2Reliability
If wireline techniques are used to remove temporary plugs, then the well can be unsealed, but the procedure is costly and poses risks (plugs can get stuck)
Solution Approach 1:
The glass plugs are designed as disposable components that are shattered to open the well rather than being removed. This eliminates the risk of plugs getting stuck during removal operations and simplifies the process by making the plug itself the opening mechanism through controlled shattering
Solution Approach 2:
Instead of designing plugs to be removed, the invention inverts the approach by designing plugs to be shattered in-place. The opening action is achieved by destroying the plug structure through controlled pressure pulses rather than mechanically retrieving it
3Reliability
If multiple glass plugs are used for sequential barriers, then sealing reliability improves, but the risk of incorrect activation increases
Solution Approach 1:
Each glass plug is equipped with its own unique bypass channel closure sequence, creating local differentiation in the activation patterns. This allows multiple plugs to be used safely with distinct operational signatures for each, maintaining reliability while enabling sequential control through localized quality variations
4Ease of operation
If a single glass plug is used, then operational simplicity is maintained, but sealing reliability and versatility are limited
Solution Approach 1:
The well suspension system is segmented into multiple glass plugs positioned at different locations, each providing independent sealing barriers. This segmentation enhances reliability by creating redundant barriers while maintaining operational simplicity through standardized activation procedures for each segment
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
Reduces operational time and cost by eliminating the need for wireline intervention vessels, ensuring precise and reliable sealing and unsealing of hydrocarbon wells, thereby enhancing safety and efficiency.
Implementation Method 1
The plug may be designed to break after a certain period of time or when a certain combination of pressure pulses is applied, for example
Data Source
AI summary
In the process of suspending a subsea hydrocarbon well (1) after finalizing the completion operation and prior to stimulation of the well and putting the well on production, preinstalled upper and lower glass plugs (11, 12) are used as temporary barriers in the tubing. The plugs allow various tests to be performed before the lower plug (12), below the production packer (10), is broken; the upper plug (11) located above the downhole safety valve (13) then forms one of the barriers required to suspend the well whilst the Blow Out Preventer (BOP) is removed and Xmas tree installed, at which point the upper plug (11) is broken.