Subterranean Casing with Varying Width for High-Pressure Storage
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Solution Overview
Problem
Current subterranean gas storage systems face challenges in maintaining high pressures (5,000 psi or more) without compromising the integrity of the casing, especially as the casing diameter increases above 9.625 inches, leading to safety concerns and reduced storage capacity due to the limitations in sealing and yield strength.
Innovation Solution
A subterranean gas storage system design featuring a casing string with a containment section of greater width between end regions, allowing for a larger diameter at the containment section while maintaining smaller diameters at the end regions, which enhances sealing and retention within the bore, thereby supporting pressures up to 5,000 psi or more.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Volume of stationary object
If the casing diameter is increased to enhance storage capacity, then the storage volume increases, but the sealing integrity and yield strength deteriorate at pressures of 5,000 psi or more
Solution Approach 1:
The casing string is divided into multiple sections with different diameters: end regions with smaller diameter (9.625 inches or less) for reliable sealing, and a central containment section with larger diameter for increased storage capacity. This segmentation allows each section to perform its optimal function while maintaining overall system reliability at high pressures.
Solution Approach 2:
Different sections of the casing string are assigned different local qualities: the end regions have smaller diameter and thicker walls optimized for sealing and pressure containment, while the central containment section has larger diameter optimized for storage volume. This local differentiation resolves the contradiction between overall storage capacity and localized sealing integrity.
2Volume of stationary object
If the casing diameter is increased above 9.625 inches to improve storage capacity, then more gas can be stored, but the safety factor decreases due to compromised casing integrity
Solution Approach 1:
The casing is segmented into smaller-diameter end regions that provide the safety factor needed for high-pressure operation, while the larger-diameter central section provides storage capacity. The smaller end regions act as safety-critical components that maintain integrity at 5,000 psi or more, allowing the system to achieve both high storage capacity and adequate safety factor.
Solution Approach 2:
The solution moves from a single-dimension (uniform diameter) design to a multi-dimensional (varying diameter along the length) design. This allows the system to optimize different sections for different functions: safety factor in the end regions and storage capacity in the central section, thereby achieving both goals simultaneously.
3Ease of manufacture
If a uniform width casing is used, then manufacturing is simpler, but storage capacity is reduced due to the need to maintain smaller diameter for sealing requirements
Solution Approach 1:
The casing string is constructed as multiple connected sections with different diameters. This segmented approach balances manufacturing complexity with storage optimization, as each section can be manufactured to standard specifications and then assembled into the final variable-diameter configuration, achieving high storage capacity without excessive manufacturing difficulty.
Solution Approach 2:
Rather than using a uniform diameter throughout, the casing applies local quality by varying the diameter along its length. This allows the majority of the casing (the central containment section) to have larger diameter for maximum storage capacity, while only the end regions maintain smaller diameter for sealing, thereby optimizing storage without requiring all sections to be manufactured to the more complex variable-diameter specification.
Data Source
AI summary
A subterranean tank can consist of at least a casing string that has a containment section disposed between first and second end regions. The containment section may have a first width while each of the first and second end regions have a second width. The first width can be greater than the second width of the respective first or second end regions. The entire casing string may be sealed to maintain a gas at 5,000 psi or more until a gas delivery assembly attached to the first end region releases gas stored in the casing string.