The influence of coal rank and mineral matter content on contact angle hysteresis

Effect of coal petrology and pressure on wetting properties of wet coal for CO2 and flue gas storage

“…(10) The found wettability behavior of the coal ranks used in this work can be related to the different surface chemistry of the coal samples. The fact that the hvBb-rank coal (WL) is more water-wet is due to hydrophilic functional groups, mainly carboxylic and hydroxyl groups, which are more abundant in the hvBb rank coal (Crawford et al, 1994;. (11) Although the underlying mechanisms causing the observed wettability alterations have not yet been identified, it is found that for CO 2 injection the wettability alterations "for our coal types" are closely related to the CO 2 sorption behavior on this same coal.…”

“…Therefore, often a distribution of contact angles is provided instead of reporting one averaged contact angle (Wei et al, 1992). It is also believed that the wettability of coal changes as function of several parameters including the coal rank , chemical composition (Brady and Gauger, 1940;Laskowski, 1994;Sun, 1954) mineral matter content (Aplan, 1993;Crawford et al, 1994;He and Laskowski, 1992), moisture level (Elyashevitch, 1941), porosity (Drelich et al, 2000;Keller, 1987), degree of oxidation (Gayle et al, 1965;Laskowski, 1994;Sun, 1954), and the pressure and temperature of the reservoir as well as the composition of the reservoir fluids (Shojai Kaveh et al, 2011). In addition, chemical heterogeneity due to the presence of different characteristic groups of components show different wetting behavior.…”

Analysis of the microscopic mechanism of coal wettability evolution in different metamorphic states based on NMR and XPS experiments

“…At the end of last century, researchers from different countries carried out a series of experiments to explore the inuence of structural differences on the wettability of coal dust and elaborated on the structural factors affecting the differences in coal dust wettability. Russell J. Crawford et al 10 studied the inuence of a series of coal ranks and mineral compositions of coals with different metamorphic degrees on the contact angle. They concluded that the hydrophobicity of the coal surface mainly relies on the ratio of carbon to oxygen (or the coal grade).…”

Mineral Matter Distribution on Coal Surface and Its Effect on Coal Wettability

“…As has already been established (4,(6)(7)(8), the mineral matter content in coals has a strong impact on the wetting characteristics of coal surfaces, although a detailed study of this effect has not been undertaken. Any approach that correlates wetting characteristics of coal specimens with ash content of particular coal should be treated with caution, simply because contact angle measurements are sensitive to the surface composition of the particular coal specimen and ash content is determined for the whole (bulk) sample.…”

“…Several researchers showed that a correlation exists between the mineral matter content and the wetting characteristic of coal (4,6,7,18). The effect of mineral matter content on contact angles was also analyzed in this study.…”