Wettability Alteration Using Silane to Improve Water-Alternating-Gas Injectivity

Area of Science:

• Geosystems Engineering
• Petroleum Engineering
• Surface Chemistry

Background:

• Wettability is crucial for multiphase flow in porous media, impacting applications like enhanced oil recovery and CO2 sequestration.
• Injectivity issues in water-alternating-gas (WAG) processes are often linked to reduced water relative permeability.
• Silane-based wettability modification is established in surface chemistry but underexplored in porous rocks.

Purpose of the Study:

• To investigate the efficacy of silane treatment for altering the wettability of sandstone and limestone.
• To reduce gas blockage and improve injectivity in porous geological formations.
• To assess the impact of silane treatment on multiphase flow characteristics at pore and core scales.

Main Methods:

• Surface modification of sandstone and limestone using silanes to induce hydrophobicity.
• Contact angle measurements to quantify wettability alteration.
• Centrifuge tests to evaluate residual fluid saturations and capillary pressure.
• Coreflooding experiments to measure changes in water relative permeability after WAG cycles.

Main Results:

• Silane treatment successfully rendered rock surfaces hydrophobic, with contact angles exceeding 90°.
• Pore-scale analysis confirmed the effectiveness of the treatment on residual fluid distribution.
• Corefloods demonstrated significant increases in water relative permeability: 45% in sandstone and 65% in limestone after WAG cycles.

Conclusions:

• Silane-based wettability alteration is an effective method for improving injectivity in sandstone and limestone.
• The treatment mitigates gas blockage and enhances water relative permeability, crucial for WAG processes.
• This approach offers a promising solution for optimizing fluid flow in geosystem applications.