Low-maturity shale oil is a strategic resource for mitigating energy shortages, yet its exploitation relies on in-situ thermal conversion where pore connectivity governs hydrocarbon migration. Supercritical CO 2 (SC-CO 2 ) offers a superior working fluid due to its unique gas-like diffusivity and liquid-like solvency, facilitating matrix penetration and heavy component extraction. However, its synergistic impact on pore evolution under confined geological conditions remains underexplored. To address this, we conducted laboratory-scale simulations on Jiufotang lacustrine shale in a closed system (300–500°C). Results indicate that SC-CO 2 significantly optimizes storage space by mitigating coke blockage and transforming discrete micropores into connected clusters. Fractal analysis indicates that, within the investigated window, SC-CO 2 reduces structural heterogeneity compared to pure pyrolysis. A critical coupling window was identified at 450°C, yielding optimal connectivity and minimal residual oil. Notably, SC-CO 2 exhibited a "temperature advancement effect," inducing early pore development and promoting a morphological transition from ink-bottle to open slit-shaped pores. These findings provide microscopic evidence from Jiufotang shale, supporting the potential integration of in-situ conversion with CO 2 utilization and storage technologies.
Sun et al. (2026) studied this question.