“…In situ crude shale oil feedstock for the hydrocracking experiment was obtained during the 28th through the 37th day of operation of a 42-day experiment in retorting by the underground combustion method at a site near Rock Springs, Wyo. (Burwell et al, 1970;Carpenter et al, 1972). The raw oil contained 0.01 wt % ash, which was removed by filtration with diatomaceous silica filter aid before the oil was hydrocracked.…”