Optimization of Soaking Time for CO2 Huff and Puff Development in Tight Oil Reservoirs

As traditional oil and gas reserves diminish, there is a growing focus on the exploitation of tight oil reservoirs. The technique of CO2 huff and puff, known for its efficacy in boosting production, is crucial in the extraction from tight oil reservoirs. This study targets the tight oil reservoir in the V oil formation within the Gao 5 fault block of the Jidong Oilfield's Gaoxin North region. Utilizing nuclear magnetic resonance (NMR) for online scanning during CO2 injection core experiments, the interaction between fractures and matrix during CO2 injection was mimicked. The analysis focused on how soaking time affects the crude oil extraction from the matrix and the efficiency of CO2 storage. The findings indicate that as soaking time increases, the recovery rate of CO2 throughput rises incrementally, with a more pronounced impact on high-cycle throughput. Furthermore, prolonging the soaking time enhances the exploitation of crude oil across various pore sizes, with the most substantial improvement observed in nanoscale pores. This research offers a theoretical foundation and technical assistance for enhancing the CO2 throughput recovery in tight oil reservoirs.