Polyrotaxane-Reinforced Cement for Entrapped Gas Pressure
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Solution Overview
Problem
Set cements, such as Portland cement, are inherently brittle and prone to cracking and explosion when gases are trapped and subjected to differential pressure, leading to explosive pressure that the cement matrix cannot withstand.
Innovation Solution
A cement composition comprising cement and a slurry containing a polyrotaxane additive, specifically a cross-linked polyrotaxane or sliding-ring polymer, and a gas-generating compound, which enhances the cement's resiliency against cracking and explosion by facilitating stress dispersion and preventing explosive pressure from causing damage.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If gas is entrapped in cement under high pressure to improve insulation or volume expansion, then the cement achieves desired functional benefits, but the cement experiences explosive pressure and cracking due to its brittle nature
Solution Approach 1:
The patent changes the physical-chemical parameters of the cement matrix by incorporating polyrotaxane additives, which modify the material's mechanical properties to become more resilient and less brittle, enabling it to withstand explosive pressure from entrapped gas
Solution Approach 2:
The patent creates a composite material system combining traditional cement with polyrotaxane additives and gas-generating compounds, where the polyrotaxane forms a reinforced network that absorbs and distributes explosive stress, preventing cracking while maintaining the desired gas entrapment functionality
2Productivity
If the percentage of gas volume in the cement matrix is increased to achieve volume expansion or insulation, then the functional performance improves, but the compressive strength of the cement is reduced
Solution Approach 1:
The patent modifies the mechanical parameters of the cement matrix through polyrotaxane addition, which strengthens the matrix and allows higher gas volume percentages without compromising compressive strength, thereby enabling both volume expansion and strength maintenance
Solution Approach 2:
The patent develops a composite system where polyrotaxane reinforces the cement matrix, creating a structure that can accommodate higher gas volumes while maintaining structural integrity and compressive strength through the synergistic combination of materials
3Ease of manufacture
If conventional cement is used without additives to maintain simplicity and cost-effectiveness, then the manufacturing process remains simple, but the cement cannot withstand explosive pressure from entrapped gas
Solution Approach 1:
The patent introduces polyrotaxane additives that modify the cement's mechanical properties, enabling it to withstand explosive pressure while maintaining a relatively simple manufacturing process that only requires mixing the additive into the cement slurry before setting
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 use of polyrotaxane additives in cement compositions significantly improves the resiliency against cracking and explosion, allowing the cement to withstand negative pressure changes without shattering, while maintaining or enhancing compressive strength.
Implementation Method 1
enhances the cement's resiliency against cracking and explosion by facilitating stress dispersion
Implementation Method 2
a cross-linked polyrotaxane comprising a polyrotaxane comprising a polymer and at least one ring compound, wherein the polymer is threaded through the cavity of the ring compound; and a cross-linker
Implementation Method 3
a gas-generating compound
Data Source
AI summary
This document relates to methods for preventing or inhibiting the cracking or explosion of cement in an oil well using cement compositions that contain polyrotaxane additives. The cement compositions containing the polyrotaxane additives exhibit increased resiliency to cracking as compared to the same cement without the polyrotaxane additive.