Brine/CO₂Interfacial Properties and Effects on CO₂Storage in Deep Saline Aquifers

Abstract

It has been long recognized that interfacial interactions (interfacial tension, wettability, capillarity and interfacial mass transfer) govern fluid distribution and behaviour in porous media. Therefore the interfacial interactions between CO<sub>2<sub/>, brine and reservoir oil and/or gas have an important influence on the effectiveness of any CO<sub>2<sub/> storage operation. There is a lack of experimental data related to interfacial properties for all the geological storage options (oil & gas reservoirs, coalbeds, deep saline aquifers). In the case of deep saline aquifers, there is a gap in data and knowledge of brine-CO<sub>2<sub/> interfacial properties at storage conditions. More specifically, experimental interfacial tension values and experimental tests in porous media are necessary to better understand the wettability evolution as a function of thermodynamic conditions and it’s effects on fluid flow in the porous media. In this paper, a complete set of experimental values of brine-CO<sub>2<sub/> Interfaciale Tension (IFT) at pressure, temperature and salt concentration conditions representative of those of a CO<sub>2<sub/> storage operation. A correlation is derived from experimental data published in a companion paper [Chalbaud C., Robin M., Lombard J.-M., Egermann P., Bertin H. (2009) Interfacial Tension Measurements and Wettability Evaluation for Geological CO<sub>2<sub/> Storage, Adv. Water Resour. 32, 1, 1-109] to model IFT values. This paper pays particular attention to coreflooding experiments showing that the CO<sub>2<sub/> partially wets the surface in a Intermediate-Wet (IW) or Oil-Wet (OW) limestone rock. This wetting behavior of CO<sub>2<sub/> is coherent with observations at the pore scale in glass micromodels and presents a negative impact on the storage capacity of a given site.