Geometric properties of rough walls induced CO2 transport at grooves during CO2 enhanced oil recovery

ZJ Wang and F Feng and L Wang and S Liu and P Gao and X Gao and SY Liu and MH Wang and XQ Lu and W Lyu, COLLOIDS AND SURFACES A-PHYSICOCHEMICAL AND ENGINEERING ASPECTS, 726, 137705 (2025).

DOI: 10.1016/j.colsurfa.2025.137705

The complexity of pore morphology in geologic reservoirs has an important impact on fluid storage and transportation, and an in-depth study of this can help to understand the complex fluid transportation mechanism in shale reservoirs. In this work, the mechanisms of CO2 flooding in different unit structures and roughness pores are thoroughly investigated. The results show that the morphology of the pores affects the fluid mobility within the pores, the formation of adsorption layers, and the emergence of mixed-phase zone discontinuity. In the unit structure, the square pore has a stronger blocking ability for oil molecules than the arched and triangular pores, which destroys the solubilization gradient and inhibits the continuous solubilization and extraction of the oil phase into the main channel of the fracture. In the symmetric rough pores, the flooding mechanism in the pore recesses is similar to that in the unit structure. The flooding mechanism in asymmetric square rough pores is similar to that in symmetric square rough pores, but the flow paths of CO2 molecules and the blockage of oil molecules at corners in arched and triangular rough pores lead to opposite manifestations of the displacement effect. The results of this work are of great significance for understanding the mechanism of CO2 flooding under complex rock pore structures.

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