Production dynamics of CO2 cyclic injection and CO2 sequestration in tight porous media of Lucaogou formation in Jimsar sag

Abstract The primary objective of this work was to comprehensively investigate the production dynamics of the CO 2 cyclic injection coupled with CO 2 sequestration efficiency in the tight porous media of Lucaogou formation in Jimsar sag, China. The PVT results showed that significant viscosity reduction and swelling of the crude oil occurred as a result of CO 2 dissolution. The tight oil recovery was correlated with the depleting pressure, through which the optimal timing for CO 2 injection was determined. The cumulative oil recovery factor (CORF) increased linearly with CO 2 slug size by causing incremental pressure and viscosity reduction; approximately 11% of original oil in place (OOIP) was produced further after a natural depletion. The oil production rate rapidly declined with the depleting core pressure. The scheme of continuous CO 2 injection was more efficient for improving tight oil recovery compared to multi stage injection and multi-cyclic operation. The CO 2 co-produced crude oils became notably heavier according to the carbon number distributions, implying that the miscibility was probably not achieved in the cyclic injection. Due to the significant capillary effect and dissolution, more than 85% of the injected CO 2 was captured in the tight porous media, verifying the potential of tight formation in CO 2 storage.