Reservoir rock wettability
has been linked to the adsorption of
crude fractions on the rock, with much attention often paid to the
bulk mineralogy rather than contacting minerals. Crude oil is contacted
by different minerals that contribute to rock wettability. The clay
mineral effect on wettability alterations is examined using the mineral
surface charge. Also, the pH change effect due to well operations
was investigated. Clay mineral surface charge was examined using zeta
potential computed from the particle electrophoretic mobility. Clay
minerals considered in this study include kaolinite, montmorillonite,
illite, and chlorite. Results reveal that the clay mineral charge
development is controlled by adsorption of ionic species and double
layer collapse. Also, clay mineral surface charge considered in this
study shows that their surfaces become more conducive for the adsorption
of hydrocarbon components due to the presence of salts. The salt effect
is greater in the following order: NaHCO3 < Na2SO4 < NaCl < MgCl2 < CaCl2. Furthermore, different well operations induce pH environments that
change the clay mineral surface charge. This change results in adsorption
prone surfaces and with reservoir rock made up of different minerals,
and the effect of contacting minerals is critical as shown in our
findings. This is due to the contacting mineral control wettability
rather than the bulk mineralogy.