Downhole Casing Buoyancy Chamber with Rupture Disc
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Solution Overview
Problem
The length of deviated or horizontal sections in well bores poses challenges in running well casing to the desired depth due to high casing drag, as long lengths of casing create significant friction, making it difficult to overcome and potentially causing the casing to become stuck.
Innovation Solution
A buoyant chamber is created within the casing using a fluid lighter than the well bore fluid, such as air or a gas like nitrogen, to reduce drag and facilitate easier placement by increasing buoyancy, and a degradable rupture disk mechanism is employed to ensure a clear flow path once the desired depth is reached.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Length of moving object
If long lengths of casing are used to reach the desired depth in deviated or horizontal well sections, then the casing can reach the target depth, but friction and casing drag increase significantly making it difficult to run the casing
Solution Approach 1:
The patent applies the anti-weight principle by introducing a buoyancy chamber filled with a buoyant fluid (lighter than the well bore fluid) within the casing. This creates an upward buoyant force that counteracts the downward gravitational force and reduces the effective weight of the casing string, thereby reducing casing drag and friction during installation in deviated or horizontal well sections.
2Ease of operation
If a buoyant chamber is created in the casing to reduce drag, then it becomes easier to run the casing to the desired depth, but the casing string becomes more complex
Solution Approach 1:
The patent applies segmentation by dividing the casing string into distinct functional segments: a buoyancy chamber section filled with buoyant fluid and a non-buoyant section. This allows the buoyant portion to reduce drag during installation while the non-buoyant portion maintains structural integrity and can be easily connected to standard casing strings, thereby managing complexity through modular design.
3Reliability
If a rupture disk is used to block flow in the buoyancy assist tool, then the buoyant fluid is contained in the chamber, but the flow path is restricted until the disk ruptures
Solution Approach 1:
The patent applies preliminary action by pre-positioning the rupture disk in the flow path of the buoyancy assist tool before casing installation. The disk remains intact during installation to maintain buoyant fluid containment, and only ruptures after the casing reaches the desired depth, automatically clearing the flow path for subsequent operations without requiring additional intervention.
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 buoyant chamber significantly reduces friction, allowing the casing to reach the desired depth without becoming stuck, while the degradable rupture disk ensures a full bore passageway for other tools, enhancing the ease of placement and reducing the risk of damage.
Implementation Method 1
Creating a buoyant chamber in the casing utilizing air or a fluid lighter than the well bore fluid can reduce the drag making it easier to overcome the friction and run the casing to the desired final depth
Implementation Method 2
The rupture disk is completely removable from a flow path through the outer case solely upon the flow of fluid therethrough
Data Source
AI summary
A downhole tool includes a casing string with a fluid barrier connected therein defining a lower end of a buoyancy chamber. A plug assembly connected in the casing string defines an upper end of the buoyancy chamber. The plug assembly has an outer case with a rupture disc positioned therein configured to block flow and to burst at a predetermined pressure. The rupture disk is removable from a flow path through the outer case upon the flow of fluid therethrough.