Optimization of CO2 Huff-n-Puff in Unconventional Reservoirs with a Focus on Pore Confinement Effects, Fluid Types, and Completion Parameters

The cyclic injection of CO2, referred to as the huff-n-puff (HnP) method, is an attractive option improve oil recovery from unconventional reservoirs. This study evaluates optimization CO2 HnP method and provides insight into aspects sequestration for Furthermore, this also examines impact nanopore confinement, fluid composition, solvent, diffusivity parameters, fracture properties on long-term factor. results over 500 independent simulations showed that optimal obtained puff-to-huff ratio around 2.73 with a soak period fewer than 2.7 days. After numerous cycles, optimized process resulted in about 970-to-1067-ton storage per 32% recovery, compared 22% natural depletion 30 years. higher effectiveness N2 scenario. Additionally, reservoirs significant pore confinement (pore size ≤ 10 nm), improved by 3% unconfined bulk phase properties. We observed 300% improvement factor fraction light hydrocarbons (C1–C6), just 50% substantial heavy (C7+). Finally, are much more important depletion. critical insights optimize operations different phases encountered