Abstract: A fluid composition comprising: (A) a liquid hardenable resin component comprising a resin; and (B) a hardening agent component comprising a hardening agent for the resin; wherein at least one of the resin or the hardening agent comprises a molecule having at least one heavy atom. The substitution of one or more heavy atoms that have a higher atomic weight than the other atoms of the molecule, increases the molecular mass of the resin or hardening agent, and hence, the density of the fluid composition. A method of treating a treatment zone of a well, the method comprising: introducing the treatment fluid into a well bore; and allowing the treatment fluid to form a hardened mass the well bore.