Abstract

Techniques have been developed to experimentally and numerically evaluate performance of CO2 huff-n-puff processes for unlocking resources from tight oil formations. Experimentally, core samples collected from a tight formation with a permeability range of 0.27-0.83 mD are used to conduct a series of coreflooding experiments. The performance of four recovery schemes, i.e., waterflooding, immiscible CO2 huff-n-puff, near-miscible CO2 huff-n-puff, and miscible CO2 huff-n-puff processes, is evaluated with the tight core samples. The waterflooding process leads to a higher oil recovery factor in comparison with the immiscible CO2 huff-n-puff process, while both the near-miscible and miscible CO2 huff-n-puff processes result in higher recovery efficiency compared to that of waterflooding. Theoretically, numerical simulation is performed to match the experimental measurements obtained in the different recovery schemes. There exists a generally good agreement between the experimental measurements and simulated results. The tuned numerical model is then employed to optimize the injection pressure and soaking time during CO2 huff-n-puff processes. It is found that the optimum injection pressure of the CO2 huff-n-puff process can be set around the minimum miscibility pressure (MMP) between crude oil and CO2, while the soaking time can be optimized for maximizing oil recovery.

You can access this article if you purchase or spend a download.