Experimental and numerical study of permeability reduction caused by asphaltene precipitation and deposition during CO2 huff and puff injection in Eagle Ford shale

摘要

The permeability reduction associated with asphaltene precipitation and deposition in gas injection EOR processes has been widely observed and well-studied in conventional plays. In our previous research, such permeability reduction due to asphaltene deposition during gas huff and puff injection process in shale core plugs were observed. In this study, experiments were conducted to investigate the permeability reduction caused by asphaltene deposition in shale core samples during the CO2 huff and puff injection process. A dead oil sample from a Wolfcamp shale reservoir was used. A core scale simulation model was built up to mimic the huff and puff injection process in the experiment and the parameters for the asphaltene deposition in shale were obtained by matching the experimental oil recovery and permeability reduction data. The asphaltene precipitation and deposition process during the CO2 huff and puff injection experiment are discussed in details based on the simulation results.