Abstract: Methods for hydraulically re-fracturing a brittle shale formation section having a Young's Modulus of 20 GPa or more are disclosed involving injecting steam through a horizontal wellbore and into the brittle shale formation section; transferring heat from the injected steam through the shale matrix to pores that contain hydrocarbon gas or liquid; rupturing at least some of the pores by heating hydrocarbon gas or liquid contained in those pores and raising the pressure of hydrocarbon gas being heated in those pores to a level sufficient to rupture those pores, weaken the structure of the brittle shale matrix, and form micro-fractures in the brittle shale matrix; and injecting hydraulic fracturing fluid through the horizontal wellbore and into the primary fracture to form one or more macro-fractures in the brittle shale matrix having a weakened structure by expanding or coalescing at least some of the micro-fractures during the injecting of the hydraulic fracturing fluid.