An improved brine-relative permeability model with hysteresis and its significance to sequestrated CO_2 in a deep saline aquifer

摘要

Relative permeability is the fundamental petrophysical property that governs the flow and distribution of sequestrated CO2 in a deep saline aquifer, which conceptually has implications on the dissolution and capillary trapping mechanisms. The significance of trapped-gas saturation on the imbibition-relative permeability of wetting brine phase has been less emphasized in the literature. Numerically computing the hysteretic brine-relative permeability at every nodal point corresponding to the wetting phase saturation (saturation history) is a challenge. Whereas, the complexity is associated with computing the endpoint-relative permeability of brine phase corresponding to the wetting phase saturation at which flow reversal is taking place. In the present paper, an improved hysteresis-relative permeability model for wetting brine phase using Land's trapping coefficient has been presented. The present relative permeability model has been validated using the experimental results from the literature. The sensitivity of considering hysteresis brine-relative permeability on flow and distribution of sequestrated CO2 in a deep saline aquifer has been numerically investigated. The observed results emphasize that the flow model, without considering the brine-relative permeability hysteresis, over-predicts the distribution of sequestrated CO2 in the system of porous medium considered.