Dissolvable Barrier Assembly for Buoyant Casing Strings
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Current systems for creating buoyant casing strings in wellbores are fragile and leave debris, making it difficult to run casing deep into horizontal wellbores efficiently.
Innovation Solution
A dissolvable barrier assembly is deployed with the casing string, featuring a holder and a barrier with different corrosion rates on its surfaces, which isolates fluid chambers and allows for controlled fluid communication, reducing frictional drag and debris.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Force
If current buoyant casing systems are used, then frictional drag is reduced, but the systems are fragile and leave debris in the wellbore
Solution Approach 1:
The barrier assembly is segmented into multiple functional components: a barrier element for fluid isolation, a holder for structural support, and seal assemblies for hydraulic isolation. This segmentation allows each component to be optimized independently - the barrier can be made from dissolvable materials that reduce debris, while the holder provides structural integrity to prevent fragility issues
Solution Approach 2:
The barrier element is designed as a disposable component made from dissolvable or erodible materials that temporarily perform their fluid isolation function during casing deployment, then dissolve to eliminate debris problems. This disposable approach resolves the contradiction by sacrificing the barrier itself rather than having it remain as fragile debris in the wellbore
2Force
If air is trapped inside the casing string to reduce density, then buoyancy increases and frictional drag decreases, but the system becomes more complex and fragile
Solution Approach 1:
The barrier assembly is pre-installed on the casing string before deployment into the wellbore. This preliminary action ensures that the fluid isolation mechanism is already in place, eliminating the need for complex post-deployment operations to create buoyancy chambers, thereby reducing overall system complexity
Solution Approach 2:
The barrier assembly extracts the fluid isolation function from the complex buoyant casing systems and implements it through a simple, self-contained device that can be easily deployed and then dissolved, reducing overall system complexity and fragility
3Ease of manufacture
If the barrier has uniform corrosion rate, then manufacturing is simpler, but controlled fluid communication cannot be achieved
Solution Approach 1:
The barrier element is designed with non-uniform corrosion properties - different regions of the barrier have different corrosion rates or resistance levels. This local quality variation allows the barrier to maintain structural integrity in some areas while controlled dissolution in other areas enables timed fluid communication, achieving adaptability without sacrificing manufacturability
Solution Approach 2:
The barrier's corrosion parameters are intentionally varied across different regions or layers. By changing the corrosion rate parameter locally, the barrier can provide both structural support and controlled dissolution functionality, enabling adaptability while maintaining relative manufacturing simplicity through standardized fabrication processes
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 dissolvable barrier assembly effectively reduces the effective weight of the casing string, minimizing frictional drag and allowing for longer horizontal wellbore runs without the need for powerful surface equipment, while also eliminating debris issues.
Implementation Method 1
a barrier positioned in the central aperture of the holder and configured to prevent the communication of fluid across the barrier whereby an uphole chamber within the casing string extending uphole from the barrier and containing an uphole fluid is hydraulically isolated from a downhole chamber within the casing string extending downhole from the barrier
Implementation Method 2
at least a portion of the uphole surface is configured to corrode when in contact with the uphole fluid at a first corrosion rate
Implementation Method 3
at least a portion of the downhole surface is configured to corrode when in contact with the uphole fluid at a second corrosion rate that is greater than the first corrosion rate
Implementation Method 4
To reduce the effective weight (the weight of the casing string observed at the surface) and frictional drag created by a casing string running along a bottom of a horizontal section of the wellbore, it is known to reduce the density of the casing string relative to fluids present in the wellbore by trapping air inside of the casing string thereby making the casing string somewhat buoyant
Data Source
AI summary
A dissolvable barrier assembly includes a holder configured to couple to a casing string and defining a central aperture, a barrier configured to prevent the communication of fluid across the barrier, wherein the barrier comprises an outer surface including an uphole surface defining an uphole end and a downhole surface defining a downhole end opposite the uphole end and having a greater surface area than the uphole surface, wherein at least a portion of the uphole surface is configured to corrode when in contact with the uphole fluid at a first corrosion rate and also wherein at least a portion of the downhole surface is configured to corrode when in contact with the uphole fluid at a second corrosion rate that is greater than the first corrosion rate.