Speaker
Description
To address the key challenges encountered in shale oil CO2 huff-and-puff development, including low sweep efficiency, severe gas channeling, and insufficient energy supplementation, a chemical-assisted CO2 enhanced huff-and-puff strategy based on interfacial regulation is proposed. Using microfluidic visualized displacement experiments, core-scale huff-and-puff tests, and online nuclear magnetic resonance (NMR) physical simulations, the synergistic effects of different chemical flooding systems on CO2 huff-and-puff performance were systematically investigated, with emphasis on oil displacement efficiency, microscopic sweep behavior, and dynamic seepage response mechanisms. The results indicate that the effectiveness of chemical-assisted CO2 huff-and-puff is fundamentally governed by the strength of the oil–water–rock interfacial film, rather than by wettability alteration or reduction in interfacial tension alone. The wettability-control-dominated RS-3 system fails to form a stable interfacial film at the pore–throat scale, allowing CO2 to preferentially migrate along oil–rock interfaces and resulting in a limited sweep volume. The interfacial-tension-reduction-dominated DZ-1 system improves oil mobilization; however, its insufficient interfacial film strength restricts its ability to suppress gas channeling. In contrast, the RH-2 system establishes a high-strength interfacial film and induces stable emulsion formation, thereby effectively regulating reservoir wettability and preferential flow pathways, and exhibits the most pronounced synergistic enhancement with CO2. Furthermore, under large-volume gas injection conditions, the dynamic energy-supplementation process during huff-and-puff can be divided into an elastic pore–throat response stage and a microfracture expansion–micropore recovery stage. During the depressurization production period, the progressive closure of elastic pore throats and microfractures dominates the rapid deterioration of seepage capacity. These findings provide a theoretical basis for optimizing CO2 huff-and-puff operational and improving shale oil development efficiency.
| Country | China |
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