Green Chemistry Approach Using Biobased Polyphenol–Silicon Complexes for Efficient Oil Displacement and Long-Term Oil Isolation

The growth in oil demand has driven technological innovation in enhanced oil recovery (EOR). Chemical flooding, widely adopted for its effectiveness in improving oil recovery, enhances the macroscopic sweep efficiency by altering interfacial properties. However, strong oil-solid adhesion leads to residual oil, posing a key technical challenge. Although low-salinity water flooding can disrupt the hydrated ion bridge structure, its efficacy is limited, and it fails to fully resolve residual oil issues. To tackle this residual oil challenge, we developed traditional Chinese medicine (TCM) composite agents based on polyphenol-silicon complexation with dual EOR functions: in situ oil displacement and long-term oil isolation. Under weak alkaline conditions, the TCM composite agent continuously reacts with silicon, overcoming van der Waals forces between crude oil and silicate, thereby effectively displacing oil in micron-scale grooves. The polyphenol-silicon complexes, along with polyphenol, form a hydrophilic coating with micro/nanostructures via π-π interactions, maintaining superoleophobic and nonadhesive properties against crude oil even after 1 week. Additionally, the TCM agents altered the wettability of shale from oil-wet to water-wet and achieved an 88.24% recovery rate in core flooding tests. This breakthrough offers a solution for crude oil recovery, promoting efficient and environmentally sustainable development in the industry.