Methods for extracting a kerogen-based product from subsurface (oil) shale formations. These methods rely on chemically modifying the shale-bound kerogen using a chemical oxidant so as to render it mobile. The oxidant is provided to a formation fluid in contact with the kerogen in the subsurface shale. An alkaline material is also provided to the formation fluid to mobilize organic acids which are produced during oxidation of the kerogen. A mobile kerogen-based product which includes the organic acids is withdrawn from the subsurface shale formation and further processed to isolate the organic acids contained therein.