Changes in migration mode of brine and supercritical CO2 in imbibition process under steady flow state of very slow fluid velocities. Issue 2 (25th May 2018)

• Record Type: Journal Article
• Authors: Kogure, Tetsuya; Zhang, Yi; Nishizawa, Osamu; Xue, Ziqiu
• Is Part Of: Geophysical journal international. Volume 214:Issue 2(2018:Aug.)
• Page Start: 1413
• Page End: 1425
• Publication Date: 2018-05-25
• Subjects: Permeability and porosity -- Hydrogeophysics -- Image processing; Geophysics -- Periodicals; 550
• DOI: 10.1093/gji/ggy210
• Languages: English
• ISSNs: 0956-540X

Abstract

SUMMARY: Relative permeability curves and flow mechanisms of CO2 and brine in Berea sandstone were investigated during a two-phase flow imbibition process, where CO2 saturation in the rock decreased from 55 to 9 per cent by stepwise decrease of CO2 /brine injection ratios. Total fluid flow velocity was 4.25 × 10 –6 m s −1, corresponding to the capillary number of order ∼10 –8 for CO2 flow. The relative permeability curves showed a slight hysteresis compared to those during the drainage process. Local CO2 saturation and the differential pressure showed temporal fluctuations when the average differential pressure showed constant values or very small trends. The fluctuations in local CO2 saturation correlate with local porosity distributions. The differential pressure between the inlet and outlet ends showed the largest fluctuation when the CO2 /brine ratio equals to one. A final brine-only injection resulted in more CO2 trapped within low-porosity zones. These results suggest important roles of ganglion dynamics in the low flow rate ranges, where fluid pathways undergo repetitive brine snap-off and coalescence of CO2 ganglia that causes morphological changes in distributions of CO2 pathways.