Systems, methods, and heaters for treating a subsurface formation are
described herein. At least one method for producing hydrocarbons from a
subsurface formation includes providing heat to the subsurface formation
using an in situ heat treatment process. One or more formation particles
may be formed during heating of the subsurface formation. Fluid that
includes hydrocarbons and the formation particles may be produced from
the subsurface formation. The formation particles in the produced fluid
may include cenospheres and have an average particle size of at least 0.5
micrometers.