Calcium-Deficient Silicate Cement for CO2-Sequestering Well Cementing
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Solution Overview
Problem
Existing cementing methods in oil and gas wells do not effectively capture and sequester carbon dioxide, and there is a need for improved methods to reduce cement density for easier placement in annular spaces.
Innovation Solution
A method involving the use of calcium-deficient calcium silicate cement compositions mixed with carbon dioxide to form a foamed cement, which can be placed in annular spaces between well bores and piping strings, with excess carbon dioxide being trapped and sequestered within the cured cement.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Weight of moving object
If cement is foamed by mixing with nitrogen to reduce density, then cement density is reduced for easier placement, but carbon dioxide capture and sequestration capability is not achieved
Solution Approach 1:
The cement composition is designed to perform multiple functions: it acts as a cementing material for well completion while simultaneously serving as a carbon dioxide capture and sequestration medium. The calcium-deficient calcium silicate provides both structural cementing properties and reactive capacity for CO2 absorption, eliminating the need for separate foaming agents like nitrogen.
Solution Approach 2:
The invention changes the chemical composition parameters of the cement by using calcium-deficient calcium silicate with specific Ca/Si ratios (less than 2:1). This compositional parameter change enables the cement to react with and sequester carbon dioxide while maintaining adequate cementing properties, thereby achieving both density reduction and CO2 capture functionality.
2Adaptability or versatility
If calcium-deficient calcium silicate cement is mixed with carbon dioxide to form foamed cement, then carbon dioxide capture and sequestration is achieved, but cement composition complexity increases
Solution Approach 1:
The calcium-deficient calcium silicate in the cement composition self-reacts with carbon dioxide to form calcium carbonate and other reaction products. This self-service mechanism captures and sequesters CO2 without requiring additional external agents, complex additives, or sophisticated mixing equipment, thereby achieving CO2 capture with relatively simple cement composition.
3Ease of manufacture
If cement slurry is placed in annular space for cementing, then well completion is achieved, but carbon dioxide is not captured or sequestered
Solution Approach 1:
The invention merges the cementing function with the carbon dioxide sequestration function into a single integrated process. The same cement slurry that is placed in the annular space for well completion also serves as the medium for capturing and sequestering carbon dioxide, combining two previously separate functions into one unified operation.
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 achieves reduced cement density for easier placement and permanent carbon dioxide capture and sequestration, enhancing the efficiency of cementing processes in oil and gas wells.
Implementation Method 1
mixing the cement slurry composition with carbon dioxide to form a foamed cement
Implementation Method 2
excess carbon dioxide being trapped and sequestered within the cured cement
Data Source
AI summary
A method of cementing an annular space between a pipe string and a well bore, the method comprising the steps of (a) providing a cement composition including a calcium-deficient calcium silicate; (b) mixing the cement composition with water to form a cement slurry; (c) mixing the cement slurry composition with carbon dioxide form a foamed cement; and (d) placing the foamed cement in the annular space between the pipe string and the wellbore.