Wettability of rock/CO2/brine and rock/oil/CO2-enriched-brine systems: Critical parametric analysis and future outlook

CO2 geo-sequestration is a promising technology to permanently store CO2 in geological formations to control the atmospheric carbon footprint. In addition, CO2 is frequently utilized in enhanced oil recovery operations to accelerate oil production. Both, CO2 geo-storage and EOR, are significantly influenced by the wettability of the associated rock/CO2/brine systems. Wettability drives the multiphase flow dynamics, and microscopic fluid distribution in the reservoir. Furthermore, while wettability is known to be influenced by varying in-situ conditions and surface chemistry of the rock/mineral, the current state-of-the-art indicates wider variabilities of the wetting states. This article, therefore, critically reviews the published datasets on CO2 wettability of geological formations. Essentially, the rock/CO2/brine and rock/crude-oil/CO2-enriched-brine contact angle datasets for the important reservoir rocks (i.e. sandstone and carbonate rocks), as well as for the key minerals quartz and calcite are considered. Also, the parameters that influence wettability are critically analyzed, and the associated parametric trends are discussed and summarized. Finally, we identify pertinent research gaps and define the outlook of future research. The review, therefore, establishes a repository of the recent contact angle data, which thus assists to enhance our current understanding of the subject. (C) 2019 Elsevier B.V. All rights reserved.