A method of lowering the temperature of a subsurface formation, e.g., a
subsurface formation including oil shale, includes completing a well
having fluid communication with the subsurface formation at a first depth
and a second lower depth. A fracturing fluid is injected into the well so
as to form a fracture at a depth of the subsurface formation, and thereby
provides fluid communication between the first and second depths in the
well. A cooling fluid is circulated under pressure through the well and
into the fracture so as to cause the cooling fluid to flow from the well,
into subsurface formation at the first depth, to the subsurface formation
at the second depth, and back into the well, thereby lowering the
temperature of the subsurface formation.