Bistable Expandable Structure for Unstable Wellbore Support
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Solution Overview
Problem
Drilling through unstable subterranean formations like clay and coal poses challenges due to instability, leading to cavity formation, blockages, and corrosion issues with traditional support methods, which limit wellbore diameter and increase operational costs.
Innovation Solution
The implementation of a bistable structure that can be expanded within the wellbore to provide stability, using an underreamer to create a larger section and a bistable structure that transitions between collapsed and expanded states to secure itself radially against the wellbore walls, preventing debris from falling and allowing continued drilling without reducing the wellbore diameter.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Stability of the object's composition
If mechanical methods are used to support unstable sections of the borehole, then wellbore stability is improved, but wellbore diameter is reduced limiting further drilling operations
Solution Approach 1:
The support structure employs a dynamic expansion mechanism where the structure is inserted in a compressed state and then expanded in-situ within the wellbore. This allows the structure to adapt to the wellbore diameter and provide stable support without permanently reducing the available drilling diameter, as the expansion occurs after insertion rather than before.
Solution Approach 2:
The support structure utilizes a nested configuration where the expandable elements are contained within each other in a compressed state during insertion. Once positioned at the target depth, the structure expands outward to provide support, effectively nesting the support function within the drilling operation without compromising wellbore diameter.
2Stability of the object's composition
If cement structures are installed to support the wellbore, then wellbore stability is improved, but reliability deteriorates due to corrosion from wellbore fluids
Solution Approach 1:
The invention changes the material parameter from cement-based support structures to metal or polymer-based expandable structures. This parameter change provides superior corrosion resistance to the corrosive wellbore fluids while maintaining the wellbore stability function, thereby improving reliability in harsh chemical environments.
3Stability of the object's composition
If traditional support methods are used, then wellbore stability is improved, but device complexity increases due to multiple installation steps
Solution Approach 1:
The support structure is divided into segmented, modular components that can be inserted and deployed sequentially or individually. Each segment can be independently positioned and expanded, simplifying the overall installation process while maintaining comprehensive wellbore support coverage.
Solution Approach 2:
The expandable support structure incorporates self-expansion capabilities where the structure automatically expands to its support configuration upon insertion or through simple activation mechanisms. This self-service feature reduces the complexity of manual installation and positioning operations.
Data Source
AI summary
A method to provide support within a wellbore includes underreaming a section of the wellbore at a depth spanning a layer of an unstable formation. The method also includes deploying a bistable structure within the wellbore at the depth of the layer of the unstable formation. Additionally, the method includes actuating an expandable packer within the bistable structure to expand the bistable structure in a radially outward direction from a longitudinal axis of the bistable structure. The bistable structure is in contact with walls of the underreamed section of the wellbore upon expanding in the radially outward direction.