Experimental Study on Supercritical CO₂ Huff and Puff in Tight Conglomerate Reservoirs

Abstract

A tight conglomerate reservoir is a kind of unconventional reservoir with strong heterogeneity, and CO₂ injection is an economical and environmentally friendly method to enhance tight oil recovery. Supercritical CO₂ is a very promising fluid medium for unconventional reservoir development due to its gas-liquid dual properties. In this study, the production effects of supercritical CO₂ and non-supercritical CO₂ in tight conglomerate reservoirs were quantitatively analyzed by huff and puff simulation experiments conducted under reservoir conditions (formation pressure 37 MPa, temperature 89 °C). Also, the influencing factors of CO₂ huff and puff production, including injection volume, soaking time, and throughput cycles, were investigated. The results showed that supercritical CO₂ improves the recovery by 4.02% compared with non-supercritical CO₂. It could be seen that supercritical CO₂ plays a positive role in improving tight conglomerate reservoirs. The optimal injection volume, soaking time, and throughput cycles were determined to be 0.50 PV, 2 h, and 3 cycles, respectively. This paper provides an important basis for the study of supercritical CO₂ production in tight conglomerate reservoirs.