Experimental Study on EOR by CO2 Huff-n-Puff and CO2 Flooding in Tight Conglomerate Reservoirs with Pore Scale

Abstract CO2-assisted EOR technologies appear to be low-cost and eco-friendly means to boost crude oil production of dense reservoirs. The potential of CO2 huff-n-puff process and CO2 flooding processes have been extensively investigated in tight sandstone reservoirs, while few work has been done in tight conglomerate reservoirs, which exhibit strong micro-heterogeneity. In the present work, we quantitatively investigated the potential of CO2 injection processes in tight conglomerate reservoirs under reservoir conditions (formation pressure 23 MPa, temperature 69 °C). High temperature and high pressure nuclear magnetic resonance (NMR) online monitoring system was used to pore-scale monitoring the change of oil saturation in-situ through NMR T2 spectrum, one-dimensional (1D) NMR spatial distribution of signal and two-dimensional (2D) NMR images. It was demonstrated that CO2 injection processes were applicable in target tight conglomerate reservoir with recovery factors of about 35 %. The results of this study pore-scale revealed the feasibility of CO2-assisted EOR technologies in tight conglomerate reservoirs.