Casing Expansion Device Seals Cement Sheath Cavities
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Solution Overview
Problem
Existing methods for sealing cavities in or adjacent to a cured cement sheath surrounding a well casing are either prone to damage, require costly drilling interventions, or have limited success rates, and are not effective for thick-walled casings or in-situ material utilization.
Innovation Solution
A method using an expansion device with edged segments that expands circumferentially spaced recesses into the inner surface of the casing section, pressing the outer surface into the surrounding cement sheath to seal cavities, which can be deployed without penetrating the casing and using in-situ materials, thereby achieving plastic deformation and permanent sealing.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a flexible sleeve made of elastomeric foam is wrapped around a well casing to seal micro-annuli, then sealing capability is improved, but the sleeve is prone to damage and detachment from the inner surface of the well casing
Solution Approach 1:
The expansion device acts as an intermediary tool that temporarily applies force to press the foam sleeve against the casing inner surface. The device includes expansion segments that can be inflated to generate sufficient pressing force, ensuring the foam sleeve maintains reliable attachment without direct permanent modification to the casing or sleeve structure.
Solution Approach 2:
The foam sleeve transitions from a compressed state during installation to an expanded state for sealing. The expansion device allows dynamic adjustment of the sleeve's radial position, enabling it to conform to the casing inner surface and maintain reliable sealing contact while avoiding damage from excessive static force.
2Reliability
If an inflatable bladder is used to expand a well casing to generate zonal isolation, then sealing is achieved, but the expansion force is limited and cannot expand thick-walled well casing together with cured cement sheath
Solution Approach 1:
The expansion device is divided into multiple expandable segments distributed around the casing circumference. Each segment can be independently inflated to apply localized expansion force, collectively generating sufficient total force to expand thick-walled casing and adjacent cement sheath while maintaining controlled deformation for reliable zonal isolation.
Solution Approach 2:
The expansion device uses pneumatic or hydraulic pressure to inflate the expandable segments, generating the high expansion forces required to deform thick-walled casing and cured cement sheath. This fluid pressure mechanism provides controllable, high-magnitude force that overcomes the limitations of mechanical expansion methods.
3Reliability
If cement replacement or supplementing techniques are used to seal the cement sheath, then sealing can be achieved, but these techniques require creating access by milling or perforating the casing and involve complicated well interventions with limited success rate
Solution Approach 1:
The method uses the existing cured cement sheath material itself as the sealing medium, eliminating the need to introduce replacement cement or supplementary materials. The expansion device simply repositions and compacts the in-situ cement to create seals, avoiding the complexity of cement replacement operations while achieving reliable sealing.
Solution Approach 2:
The method extracts the essential sealing function from the complex cement replacement process, isolating only the necessary mechanical action of expanding and compacting the existing cement. This eliminates unnecessary steps such as milling, perforating, and introducing new cement materials, significantly reducing intervention complexity while maintaining sealing effectiveness.
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 method effectively reduces leak rates by 100-fold and provides a cost-effective, reliable sealing solution that can be deployed without a drilling rig, using in-situ materials to seal micro-annuli and cavities along the wellbore length.
Implementation Method 1
pressing circumferentially spaced recesses into an inner surface of the selected casing section and expand the outer surface of the selected the expanded casing section into the surrounding cement sheath thereby sealing the cavities
Data Source
AI summary
A method for sealing cavities in or adjacent to a cured cement sheath (4) surrounding a well casing (3) of an underground wellbore comprises: —providing an expansion device (1) with edged expansion segments (2) that is configured to be moved with the expansion segments (2) in an unexpanded configuration up and down through the well casing (3); —moving the unexpanded expansion device (1) to a selected depth in the well casing (3); and —expanding the edged expansion segments (2) at the selected depth, thereby plastically expanding a selected casing section and pressing the expanded casing section into the surrounding cement sheath thereby sealing the cavities.