Expandable Compositions in Cement Top Jobs for Annulus Gas Sealing
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Solution Overview
Problem
Gas migration through pathways in wellbore annuli due to poor cement integrity poses a challenge, leading to sustained casing pressure and requires costly remediation, which can be addressed by improving cement top jobs.
Innovation Solution
Deploying an expandable composition, such as polyurethane formed from an isocyanate and organic polyol, at the top of the cement annulus to seal and control gas migration, using methods that include mixing components and pumping them through a conduit to form an expanded composition.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If traditional cement is added to the top of the cement annulus to seal gas migration pathways, then gas migration control is improved, but the complexity of the operation and cost increase
Solution Approach 1:
The patent changes the physical and chemical parameters of the sealing material by using expandable polymer compositions that undergo phase transition from liquid to expanded solid state. This allows the material to be pumped in a manageable liquid form through standard equipment, then expand in-situ to create effective seals, thereby improving gas migration control while maintaining operational simplicity
Solution Approach 2:
The patent employs composite polymer compositions comprising multiple components (isocyanate, polyol, blowing agent, catalyst) that work together to achieve expansion and sealing. This composite approach provides both the flowability needed for easy deployment and the expansion capability for effective gas migration control, resolving the contradiction between reliability and operational complexity
2Reliability
If cement height is increased to seal gas pathways, then gas migration control improves, but the volume of material required and operational complexity increase
Solution Approach 1:
The patent utilizes phase transition of the polymer composition from liquid to expanded solid state directly in the annulus. The material is pumped as a liquid that occupies minimal volume, then expands in-situ to fill gas pathways and create seals. This eliminates the need to pump large volumes of traditional cement while achieving superior gas migration control
Solution Approach 2:
The expandable polymer provides sealing through vertical expansion into gas pathways rather than requiring increased horizontal cement height. The material expands upward and laterally to seal pathways, achieving effective gas migration control with reduced overall material volume compared to traditional cement top jobs
3Reliability
If expandable composition is used to seal the annulus, then gas migration control improves, but the manufacturing precision and mixing requirements increase
Solution Approach 1:
The patent segments the polymer composition into separate components (isocyanate component, polyol component, blowing agent, catalyst) that are stored and transported separately, then combined in controlled ratios during deployment. This segmentation allows each component to be optimized independently while simplifying the overall mixing process through standardized mixing equipment and procedures
Solution Approach 2:
The patent introduces a pre-flush fluid as an intermediary substance that prepares the annulus environment before polymer deployment. This pre-flush fluid removes contaminants and creates optimal conditions for polymer expansion and sealing, reducing the precision requirements for polymer mixing and deployment while enhancing overall gas migration control
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 expandable composition effectively seals the annulus, reducing gas migration and maintaining gas-tight seals over time, minimizing shrinkage and permeability, and optimizing expansion and curing properties for effective gas-migration control.
Implementation Method 1
allowing the expandable composition to form an expanded composition that seals the annulus above the top of cement
Implementation Method 2
mixing a first component and a second component to form the expandable composition
Implementation Method 3
the first component comprises an isocyanate and the second component comprises an organic polyol and wherein the expandable composition is a polyurethane
Implementation Method 4
optimizing expansion and curing properties for effective gas-migration control
Data Source
AI summary
A method of deploying an expandable composition in a cement top job in a well system includes identifying evidence of actual or potential gas migration within an annulus cement of the well system. Once the evidence of gas migration is identified, a first component and a second component are mixed in a mixer to form the expandable composition and the expandable composition is pumped from the mixer through a conduit to a top of cement of the annulus cement. The expandable composition expands to form an expanded composition that seals the annulus above the top of cement of the annulus cement. Cement can be added onto the expanded composition.