The present invention is directed to methods for extracting a kerogen-based product from subsurface (oil) shale formations, wherein such methods rely on fracturing and/or rubblizing portions of said formations so as to enhance their fluid permeability, and wherein such methods further rely on chemically modifying the shale-bound kerogen so as to render it mobile. The present invention is also directed at systems for implementing at least some of the foregoing methods. Additionally, the present invention is also directed to methods of fracturing and/or rubblizing subsurface shale formations and to methods of chemically modifying kerogen in situ so as to render it mobile.