A method for zone isolation, profile modification, remedial cementing, or replacing a damaged or corroded casing with a solid plastic is described. A solidifiable epoxy resin mixture, containing a critical amount of a hardener and curing agent for improved pumpability, is placed into a wellbore so as to bind with undamaged casing and close off any thief zones. Subsequently, the epoxy resin mixture forms a hardened solid underwater and/or at low wellbore temperatures that is able to withstand downhole stresses. The hardened solid is milled out if necessary so as to form a resinous casing the size of the original casing. Later, the hardened resinous casing is perforated to communicate with a targeted zone. Perforation is not required when isolating a zone. The hardened solid is of a strength sufficient to withstand stresses generated during EOR operations such as carbon dioxide or steam-flooding. Said solid is also resistant to workover acids and other chemicals used in EOR operations.