Abstract The efficient development of tight sandy conglomerate reservoirs remains challenging due to their complex pore structures and ultra-low permeability. This study aims to provide operational guidance for CO2 huff-and-puff, a promising enhanced oil recovery technique for such reservoirs. A systematic series of core-flooding experiment was conducted to quantify the impact of five key operational parameters: timing, permeability, CO2 injection volume, soaking time, and cycle number. The results provide quantitative design criteria: initiating the process early at a higher reservoir pressure (37.0 MPa) yielded a recovery factor of 17.86%, which is 3.2 times greater than that achieved at the bubble-point pressure. Increasing permeability from 0.05 to 2.94 mD enhanced recovery by 11.15% by improving sweep efficiency. An injection volume of 0.50 PV was identified as the optimal trade-off between recovery factor (17.86%) and CO2 utilization efficiency (0.19 m3/m3). Soaking beyond 120 minutes offered diminishing returns (yielding1% incremental recovery), and three operational cycles were determined as the economic limit, achieving a cumulative recovery of 26.83%. Furthermore, high-fidelity empirical correlations (R2 0.96) were developed, revealing distinct hierarchies of parameter influence: for the recovery factor, the order is timing injection volume permeability soaking time. For the CO2 oil displacement efficiency, the hierarchy is timing permeability injection volume soaking time. This work translates experimental insights into practical models and clear operational guidelines, providing a direct pathway to optimize CO2 huff-and-puff performance in analogous tight conglomerate reservoirs.
Gao et al. (Thu,) studied this question.