Elastic Coating Composition for Gas Well Micro Annuli Sealing
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Solution Overview
Problem
Conventional swell packers for sealing micro annuli between cement and casing in wellbores are unsuitable for gas wells, as they do not swell adequately with methane gas and are thick, making them impractical for installation and expansion in drilling sites, and existing solutions require dedicated workshops for manufacturing and heat treatment.
Innovation Solution
A liquid coating composition comprising a curable elastic thermosetting resin, a curing agent, and a water-absorbing expansion agent is applied to wellbore tubing, which cures in situ to form a thin, elastic seal that absorbs water from gas phases, expanding to seal micro annuli without the need for separate lubrication and can withstand high temperatures and chemical exposure.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional swell packers are used to seal micro annuli, then sealing function is provided, but they are too thick and do not swell adequately with gas phases
Solution Approach 1:
The invention changes the chemical composition parameters of the swelling material by incorporating superabsorbent polymers capable of swelling in both water and hydrocarbon environments. This allows the coating to achieve adequate swelling response in gas well conditions where conventional packers fail, while maintaining a thin profile through optimized material formulation rather than thick structural design
Solution Approach 2:
The invention uses composite material formulation combining superabsorbent polymers with elastic thermosetting resins and curing agents. This composite approach creates a multi-functional coating that provides both the swelling capability needed for sealing and the structural integrity required for thin-layer application, resolving the contradiction between thickness and sealing effectiveness
2Reliability
If preformed swell packers are manufactured with heat treatment, then adhesion and curing are achieved, but dedicated workshops and large ovens are required
Solution Approach 1:
The coating composition contains self-contained curing agents that enable the coating to cure and adhere to the casing surface without external heat treatment infrastructure. The chemical curing process occurs in situ after application, eliminating the need for dedicated workshops and large ovens while maintaining reliable adhesion and curing
Solution Approach 2:
The invention replaces the mechanical/thermal curing system (heat treatment in ovens) with a chemical curing system using reactive components within the coating formulation. This substitution eliminates complex manufacturing infrastructure while achieving the same adhesion and curing objectives through chemical reactions
3Reliability
If conventional swell packers are applied, then sealing is provided, but they require separate lubrication and cannot be easily applied at drilling sites
Solution Approach 1:
The invention merges multiple functions into a single coating application: the coating provides lubrication during installation, forms an adherent bond to the casing surface, and creates the swelling seal. This consolidation of functions into one applicatable layer eliminates the need for separate lubrication steps and enables easy application at drilling sites
Solution Approach 2:
The coating composition is designed with multi-functionality, serving as lubricant, adhesive, and sealing material simultaneously. This universal approach allows the same material to perform multiple operations that would traditionally require separate components or steps, greatly simplifying the application process at drilling sites
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 coating provides a self-healing, leak-tight seal for micro annuli in gas wells, maintaining structural integrity and preventing fluid communication between cement and casing, while being easily applicable at drilling sites and compatible with gas well conditions.
Implementation Method 1
a water-absorbing expansion agent is added to the composition. The coating provides a self-healing, leak-tight seal for micro annuli in gas wells
Implementation Method 2
providing a coating composition in a liquid state at a selected wellbore site, the coating composition comprising a curable elastic thermosetting resin
Data Source
AI summary
The invention concerns a method of applying a coating in a liquid state to wellbore tubing, such as threaded connector parts or casing sections, before running the tubing downhole. The coating only cures while running downhole. The coating is an elastic curable coating composition, comprising a curable elastic thermosetting resin, a curing agent and a water-absorbing expansion agent. During make-up of a connector, the liquid coating composition acts as lubricant. When cured, the coating will swell when contacted with a wellbore fluid to ensure leak-tightness.