Multiscale Quantitative Characterization of Basalt Pore and Throat Networks Using Micro-CT: Implications for...

Area of Science:

• Geology
• Geochemistry
• Petroleum Engineering

Background:

• Pore-throat structure and connectivity critically influence injectivity and fluid migration in basalt reservoirs for carbon dioxide (CO2) storage.
• Understanding these characteristics is vital for assessing reservoir potential and ensuring safe CO2 sequestration.

Purpose of the Study:

• To quantitatively characterize the pore-throat structure and connectivity in Cenozoic basalt matrix samples.
• To develop a model for predicting fluid flow capacity based on pore-network characteristics.

Main Methods:

• High-resolution micro-CT imaging for pore structure visualization.
• Three-dimensional reconstruction and pore-network modeling.
• Integration of core-scale porosity and permeability measurements.

Main Results:

• Basalt samples exhibit high total porosity (23.96%) but very low permeability (0.07 mD) at the core scale.
• Matrix-scale connected porosity (0.68%) is significantly lower than total porosity (3.99%), indicating poor connectivity.
• Effective flow is dominated by a sparse network of larger pores (>15 μm) and open throats, forming a connected backbone.

Conclusions:

• Fluid flow in basalt reservoirs is controlled by a connected-backbone structure, not solely by total porosity.
• Mineral filling and narrow pore throats significantly impede flow continuity.
• The proposed model aids in evaluating basalt reservoir injectivity and identifying effective flow pathways for CO2 storage.