Investigation of asphaltene deposition mechanisms during CO2 huff-n-puff injection in Eagle Ford shale

In this study, laboratory tests were conducted to investigate the asphaltene deposition mechanisms during CO2 huff-n-puff injection in an Eagle Ford shale core using Wolfcamp shale oil. The permeability reduction due to asphaltene deposition by mechanical plugging and adsorption mechanisms were determined using the n-Heptane and toluene reverse flooding, respectively. The results showed that 83% of the total permeability reduction is due to asphaltene deposition by mechanical plugging mechanism, while 17% of the total permeability reduction is due to asphaltene deposition by adsorption mechanism. The critical interstitial velocity for entrainment of asphaltene deposition was around 0.0008 cm/sec.