Monitoring CO2 invasion processes at the pore scale using geological labs on chip

Area of Science:

• Geosciences
• Petroleum Engineering
• Chemical Engineering

Background:

• Understanding pore-scale mechanisms of CO2 injection is crucial for carbon capture, utilization, and storage (CCUS) and enhanced oil recovery (EOR).
• Previous studies often lack the resolution to observe real-time, pore-scale fluid dynamics under relevant geological conditions.

Purpose of the Study:

• To investigate pore-scale mechanisms during CO2 injection into water-saturated porous media.
• To analyze the influence of pressure, temperature, injection rates, and pore network characteristics on CO2 displacement.
• To identify and characterize conventional and counterintuitive CO2-fluid interaction mechanisms.

Main Methods:

• Utilized high-pressure micromodels, termed geological labs on chip (GLoC), simulating reservoir conditions (25-75°C, 4.5-8 MPa).
• Conducted a series of CO2 displacement experiments varying key parameters.
• Employed on-chip optical characterization and imaging for real-time monitoring and data acquisition.

Main Results:

• Determined CO2 saturation curves as a function of time and injected pore volumes.
• Observed three primary displacement mechanisms: invasion, percolation, and drying.
• Documented two counterintuitive phenomena during the invasion and drying stages of CO2 injection.

Conclusions:

• GLoC experiments provide critical insights into pore-scale CO2-water interactions under simulated geological conditions.
• The identified mechanisms, including novel observations, enhance the understanding of CO2 behavior in subsurface environments.
• Findings contribute to improved modeling and prediction of CO2 storage and EOR processes.