Dissolution-precipitation processes in tank experiments for testing numerical models for reactive transport...

Area of Science:

• Geochemistry
• Hydrogeology
• Computational modeling

Background:

• Reactive transport codes require validation with experiments that couple multiple physical and chemical processes.
• Existing experiments often lack the flexibility to incorporate density-driven flow and kinetically controlled reactions simultaneously.

Purpose of the Study:

• To develop a simple, reproducible 2D reactive transport experiment for validating numerical models.
• To investigate the coupling of advective-diffusive transport, density-driven flow, and mineral precipitation/dissolution affecting porosity and permeability.

Main Methods:

• A 2D experimental setup with a strontium sulfate (SrSO4) reactive layer between quartz sand layers was used.
• Barium chloride solution injection induced SrSO4 transformation to barium sulfate (BaSO4), altering porosity and permeability.
• Experiments were simulated using the OpenGeosys-GEM reactive transport code, incorporating pore-scale analysis for pressure evolution.

Main Results:

• The model accurately reproduced non-reactive tracer tests and density-driven flow.
• Mineral transformation and its impact on porosity and permeability were investigated.
• Post-mortem pore-scale analysis was crucial for accurately modeling pressure changes.

Conclusions:

• The developed experiment serves as a valuable benchmark for reactive transport codes.
• Coupling of physical and chemical processes, including pore-scale effects, is essential for accurate reactive transport modeling.
• Further refinement of porosity-permeability relationships considering mineral precipitation is needed.