Methods and compositions for thermally shocking subsurface formations

A method of thermally shocking a subsurface formation, the method comprising:

• crosslinking an endothermic fluid composition with a crosslinker to form a crosslinked endothermic fluid composition, the endothermic fluid composition comprising an aqueous solution, a polymer, and ammonium chloride;
• introducing the crosslinked endothermic fluid composition into a wellbore fluidly connected to the subsurface formation;
• introducing an endothermic booster fluid into the wellbore before or after introducing the crosslinked endothermic fluid composition, the endothermic booster fluid comprising a second aqueous solution and a hydroxide-containing compound;
• exposing the crosslinked endothermic fluid composition to the subsurface formation, wherein a temperature of the subsurface formation breaks the crosslink of the crosslinked endothermic fluid composition and exposes the ammonium chloride;
• reacting the ammonium chloride that has been exposed with fluids of the subsurface formation, thereby decreasing a temperature of the subsurface formation and producing ammonia;
• reacting the ammonium chloride with the hydroxide-containing compound of the endothermic booster fluid, thereby further decreasing a temperature of the endothermic fluid composition and producing additional ammonia;
• and
• thermally shocking the subsurface formation via the decreased temperature and produced ammonia, thereby inducing a plurality of fractures in the subsurface formation.