Quantification of CO₂ Mineralization at the Wallula Basalt Pilot Project

Area of Science:

• Earth Sciences
• Geochemistry
• Environmental Science

Background:

• Geologic carbon sequestration is a key strategy for mitigating climate change.
• The Columbia River Basalt Group is a potential host formation for CO2 storage.
• Previous studies indicated potential for carbonate mineralization of CO2 in basalt.

Purpose of the Study:

• To analyze hydrologic test data from a geologic carbon sequestration field demonstration.
• To quantify the amount of injected CO2 mineralized in basalt formations.
• To assess changes in reservoir conditions post-CO2 injection.

Main Methods:

• Comparative analysis of pre-injection (2012) and post-injection (2015) hydrologic tests.
• Utilizing differences in fluid properties between supercritical CO2 (scCO2) and water.
• Reactive transport modeling to interpret hydrologic data and mineralization extent.

Main Results:

• Hydrologic test analysis revealed significant changes in near-field, wellbore, and reservoir conditions.
• Modeling indicated approximately 60% of injected CO2 was sequestered via mineralization within two years.
• Formed carbonates occupied approximately 4% of the reservoir pore space.

Conclusions:

• The comparative hydrologic test method effectively quantifies CO2 mineralization in basalt.
• Geologic sequestration in basalt formations can lead to substantial CO2 mineralization.
• This monitoring approach can be adapted for traditional subsurface carbon storage verification.