A sister Luxembourg sandstone, which was inherently water-wet, was chemically treated to change the wettability to mixed-wet by immersing the cleaned and dried sample in 25 ml of decane with 5 wt.% octadecyltrichlorosilane (OTS). In the quasi-static oil- and waterflooding experiments, the decane and brine (i.e. deionized water doped with 25 wt% potassium iodine) were used as oil phase and watery phase respectively.
