Wettability behaviour of CO2 at storage conditions

A statistical analysis of the effects of pressure, temperature and salinity on contact angles in CO 2 –brine–quartz systems

“…For example, the generally understood influence of surface roughness on wettability is that increased roughness should decrease contact angles on hydrophilic surfaces and increase them on hydrophobic ones (Bikkina, 2011), and that it is one of the factors controlling hysteresis (Andrew et al, 2014;Dickson et al, 2006;Yuan and Lee, 2013). Despite being a potential source of "spurious effects on measurements" (Farokhpoor et al, 2013a) that warrants "a thorough surface preparation" , surface roughness is often unreported in published accounts of contact angle measurements. Only five of the studies examined in our analysis (Jung and Wan, 2012;Saraji et al, 2013Saraji et al, , 2014Wang et al, 2013;Sarmadivaleh et al, 2015) reported the roughness of the surfaces tested and surface roughness was therefore not included in our models.…”

“…The only study that would change the significance of the fixed effect estimates is that of Farokhpoor et al (2013a), which would reduce the test statistic (t) to statistically insignificant values for temperature in both models if that study were removed from the pooled data. The results of Farokhpoor et al (2013a), while novel, are not unique in finding a marked change in wettability with temperature (in their case, an increase in contact angles by 8 • to 14 • as temperature changed from 33 • C to 66 • C); Saraji et al (2013) also reported a temperature effect on contact angles of similar magnitude as temperatures increased from 35 • C to 60 • C, and so the importance of the data from Farokhpoor et al (2013a) to the temperature estimate is not clear. We do note, however, that experiments of Farokhpoor et al (2013a) cover a wide range of pressure values (extending beyond any other study and up to 40 MPa) and were conducted at three different brine concentrations (0 mol/L, 0.2 mol/L, 0.8 mol/L), which may explain why their data carry more influence on the model results for temperature than other studies.…”

“…Water contact-angle measurements versus pressure from ten studies, demonstrating the large discrepancies in measurements. Notably, while some studies show a trend of increasing contact angles with pressure for values below ∼10 MPa (Chiquet et al, 2007;Bikkina, 2011;Broseta et al, 2012;Jung and Wan, 2012;Sarmadivaleh et al, 2015), others do not (Espinoza and Santamarina, 2010;Farokhpoor et al, 2013a).…”

Contact angle measurement ambiguity in supercritical CO2–water–mineral systems: Mica as an example

“…Under the reservoir conditions of GCS, capillarity exerts large controls on the movement and distribution of CO 2 and brine, and wettability is a key factor impacting the magnitude and direction the capillary force (Anderson, 1986;Dullien, 1992;Iglauer et al, 2011;Morrow, 1990;Pentland et al, 2011;. Wetting phenomena in mineral-brine-CO 2 systems have been under active investigation in recent years, and improved understanding has been obtained in this short period of time (Bikkina, 2011;Broseta et al, 2012;Chiquet et al, 2007;Espinoza and Santamarina, 2010;Farokhpoor et al, 2013;Jung and Wan, 2012;Kim et al, 2012Kim et al, , 2013Mills et al, 2011;Shah et al, 2008;Wang et al, 2013a,b;Yang et al, 2008). However reported contact angle (denoted here as CA) values vary over a large range, and it is still unclear whether or not long-term reaction with scCO 2 changes the wettability of the reservoir minerals.…”

“…A few groups have reported measured CAs of mica-CO 2 -brine systems (Broseta et al, 2012;Chiquet et al, 2007;Farokhpoor et al, 2013;Mills et al, 2011;Saraji et al, 2014;Shah et al, 2008;Wang et al, 2013a). For example, Chiquet et al (2007) reported the CA changed from water-wet behavior at low pressure toward intermediate wet at high pressure (>10 MPa).…”