Produced Brine Softening via CO2 Carbonate Precipitation
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Solution Overview
Problem
Produced water from oil and gas fields, rich in divalent cations like calcium and magnesium, poses challenges due to its corrosiveness and environmental impact, making it unsuitable for industrial and agricultural applications and hindering enhanced oil recovery processes.
Innovation Solution
A method involving CO2 mineralization in produced oilfield brine to form calcium and magnesium carbonates, followed by filtration to produce softened water, which is then injected into subterranean formations for enhanced oil recovery.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If produced brine is used for enhanced oil recovery, then oil recovery can be enhanced, but scale formation and corrosion occur due to high divalent ion concentration
Solution Approach 1:
The patent extracts and removes divalent cations (calcium and magnesium ions) from the produced brine through precipitation and filtration processes. By taking out these harmful ions, the brine is softened to prevent scale formation and corrosion while maintaining its utility for enhanced oil recovery operations
Solution Approach 2:
The patent converts the harmful effect of divalent ions into a beneficial process by utilizing them to precipitate carbonate minerals. The high divalent ion concentration, which originally causes corrosion and scale formation, is now harnessed to remove CO2 through mineralization, transforming a harmful characteristic into a useful mechanism for carbon sequestration and brine softening
2Productivity
If CO2 is dissolved in produced brine, then CO2 sequestration is achieved, but divalent ions remain causing corrosiveness
Solution Approach 1:
The patent extracts divalent cations from the CO2-charged brine through precipitation reactions that form insoluble carbonate minerals. By removing these ions via filtration, the corrosiveness of the brine is eliminated while preserving the CO2 sequestration benefits
Solution Approach 2:
The patent introduces a base (such as NaOH or NH3) as an intermediary substance that facilitates the precipitation of divalent ions as carbonates. This intermediary enables the removal of harmful ions without interfering with the CO2 mineralization process, allowing both CO2 sequestration and corrosion prevention to occur simultaneously
3Productivity
If base is added to CO2 charged water, then solid carbonates are formed, but filtration is required to remove them
Solution Approach 1:
The patent utilizes parameter changes in pH to control the formation and removal of carbonates. By adjusting the pH through base addition, insoluble carbonate precipitates are formed, which can then be easily separated through filtration. The parameter change enables both efficient carbonate formation and simple removal of solid products
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 effectively sequesters CO2, reduces divalent ions, preventing scale formation and corrosion, and enhances the injectivity of water flooding processes by mitigating formation damage.
Implementation Method 1
dissolving gaseous carbon dioxide (CO2) in a produced oilfield brine
Implementation Method 2
adding a base to the CO2 charged water to yield a basic CO2 charged slurry, wherein the basic CO2 charged slurry comprises solid carbonates
Data Source
AI summary
Method for softening produced oilfield brine for enhanced oil recovery, the method including dissolving gaseous carbon dioxide and a base in a produced oilfield brine that includes divalent ions to yield solid carbonates, filtering the solid carbonates to yield a softened water, and injecting the softened water into a subterranean formation.