Annular Barrier Segmented Sleeve Pressure Compensation
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Solution Overview
Problem
Existing annular barriers for well completion often fracture or damage formations due to excessive expansion energy when the borehole diameter is smaller than expected, as they lack effective pressure compensation mechanisms.
Innovation Solution
An annular barrier design featuring an expandable sleeve with distinct sections, where the first sections have a larger thickness or inner diameter than the second section, allowing excess expansion energy to expand the smaller sections, thereby compensating for varying borehole diameters and preventing fracture.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If a uniform thickness expandable sleeve is used, then the structure is simple and easy to manufacture, but the sleeve may fracture or damage the formation when borehole diameter is smaller than expected due to excessive expansion energy
Solution Approach 1:
The expandable sleeve is divided into multiple sections with different thicknesses. The first section has a larger thickness than the second section, creating a segmented structure that provides passive pressure compensation. This segmentation allows the sleeve to handle varying borehole diameters safely, preventing fracture while maintaining manufacturability.
Solution Approach 2:
Different sections of the expandable sleeve have different local properties (thicknesses). The first section has a larger thickness to provide compensation for excess expansion energy, while the second section has a smaller thickness for normal operation. This local quality variation enables the sleeve to adapt to different borehole conditions without compromising overall reliability.
2Reliability
If the expandable sleeve has varying thickness sections, then passive pressure compensation is achieved and reliability is improved, but the device complexity increases
Solution Approach 1:
The sleeve is segmented into sections with different thicknesses, where the first section has larger thickness than the second section. This segmentation provides passive pressure compensation capability while maintaining a relatively simple overall structure that does not significantly increase device complexity.
Solution Approach 2:
The thickness parameter of the expandable sleeve is changed across different sections. The first section has a larger thickness parameter to provide compensation, while the second section has a smaller thickness parameter for normal operation. This parameter variation achieves reliability improvement with minimal increase in device complexity.
3Use of energy by moving object
If a compound is heated to expand the annular barrier, then expansion energy is generated, but excess expansion energy can damage the formation or collapse the casing when borehole diameter is smaller than expected
Solution Approach 1:
The first section of the expandable sleeve with larger thickness acts as a cushion that absorbs excess expansion energy before it can reach the formation or casing. This beforehand cushioning prevents formation damage and casing collapse by providing a safety buffer against over-expansion when borehole diameter is smaller than expected.
Solution Approach 2:
The excess expansion energy that would normally cause harm is converted into a beneficial effect by designing the first section with larger thickness. This section absorbs the excess energy, transforming what would be a harmful over-expansion force into a controlled expansion that still achieves the desired barrier function without damaging the formation or casing.
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 design enables the annular barrier to accommodate a range of borehole diameters without fracturing, ensuring reliable zone isolation and preventing damage to the formation or casing, by utilizing a thermally decomposable compound that generates expansion energy, which is managed through the varying thickness and diameter sections.
Implementation Method 1
the annular space comprising a compound adapted to expand the annular space when subjected to heat
Data Source
Figure 1
Figure 2a
Figure 2b
AI summary
The present invention relates to an annular barrier to be expanded in an annulus between a well tubular structure and an inside wall of a borehole downhole for providing zone isolation between a first zone and a second zone of the borehole, the annular barrier comprising a tubular metal part for mounting as part of the well tubular structure, an expandable sleeve surrounding the tubular metal part and having an inner face facing the tubular metal part and an outer face facing the inside wall of the borehole, each end of the expandable sleeve being connected with the tubular metal part, and an annular space between the inner face of the expandable sleeve and the tubular metal part, wherein the tubular part and the inner face of the expandable sleeve substantially hermetically enclose the annular space, the annular space comprising a compound adapted to expand the annular space, and wherein the expandable sleeve comprises two first sections abutting the ends of the expandable sleeve and a second section between the first sections, the first section of the expandable sleeve has a first inner diameter in an unexpanded condition of the annular barrier, and the second section of the expandable sleeve has a second inner diameter in the unexpanded condition, which second inner diameter is larger than the first inner diameter in the unexpanded condition, or the first sections have a first thickness which is larger than a second thickness of the second section in the unexpanded condition. Furthermore, the invention relates to a downhole system and a method of expanding an annular barrier.