Wellbore Cement Polymer Capsules Microannuli Sealing
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Solution Overview
Problem
Wellbore cementing operations often fail due to thermal-mechanical stresses, leading to debonding and microannuli formation, which results in hydrocarbon migration and pressure buildup, compromising production and safety, and failing to provide adequate zonal isolation.
Innovation Solution
Incorporating polymer capsules within the cement slurry that rupture to release encapsulants, enhancing the cement's elasticity and sealing capabilities, and strategically controlling the release of signaling agents to mitigate fluid migration and pressure issues.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If traditional wellbore cement is used, then the cement provides initial bonding and isolation, but thermal-mechanical stresses cause debonding and microannuli formation, leading to loss of zonal isolation
Solution Approach 1:
The patent modifies the cement's mechanical properties by incorporating polymer capsules that change the cement's elasticity and tensile strength parameters, allowing the cement to better withstand thermal-mechanical stresses without debonding or forming microannuli
Solution Approach 2:
The patent creates a composite cement material by combining traditional cement with polymer capsules containing elastomeric materials, resulting in a composite that exhibits both the bonding properties of cement and the flexibility of polymers to maintain seal under stress
2Stress or pressure
If high density cement is used to control gas migration, then hydrostatic pressure is sufficient to control formation pressure, but permeable channels form during setting, allowing gas to travel up through the cement column
Solution Approach 1:
The patent changes the rheological parameters of the cement slurry by incorporating polymer capsules, which modify the fluid's viscosity and flow characteristics during setting, preventing the formation of permeable channels while maintaining sufficient hydrostatic pressure to control gas migration
3Ease of operation
If cement slurry with high fluid loss is used, then the slurry can be pumped, but water accumulation causes micro-fractures within the cement body, resulting in failures
Solution Approach 1:
The patent modifies the fluid loss parameters of the cement slurry by incorporating polymer capsules, which control water retention and prevent excessive fluid loss during pumping and setting operations, thereby preventing micro-fracture formation while maintaining pumpability
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 enhanced cement maintains sealing and adhering interfaces, reduces microannuli formation, and effectively manages pressure and fluid migration, ensuring the integrity of the wellbore and preventing contamination.
Implementation Method 1
the encapsulant is released from at least some of the polymeric shells by osmosis, and where the empty polymeric shells form spent capsules
Data Source
AI summary
Capsules with a cement additive covered by a polymeric outer shell are added to wellbore cement. The additive is released from the shells by osmosis or shell ruptures. Capillary forces draw the additive into micro-annuli or cracks present in the cement, where the additive seals the micro-annuli and cracks to define a self-sealing material. The empty shells remain in the cement and act as an additive that modifies cement elasticity. The capsules are formed by combining immiscible liquids, where one of the liquids contains a signaling substance, and each of the liquids contains a reagent. When combined, the liquids segregate into a dispersed phase and a continuous phase, with the dispersed phase having the signaling agent. The reagents react at interfaces between dispersed and continuous phases and form polymer layers encapsulating the signaling agent to form the capsules. Adjusting relative concentrations of the reagents varies membrane strength and permeability.