Abstract: A method for treating a subterranean formation penetrated by a wellbore is carried out introducing a treatment fluid into the formation through the wellbore wherein the formation has a formation temperature of at least 70° C. A composition for such treatment is also provided. The composition and treatment fluid for the method is formed from water and an amount of fibers formed from high temperature polymers of at least one of a polyester, polyamide, polyurethane, polyurea polymers, and copolymers of these. Each of said high temperature polymers is characterized by the property of not substantially degrading in water at a pH of from 5 to 9 at temperatures below 80° C. A fiber degrading accelerant that facilitates degrading of the fibers at the formation temperature is also included in the treatment fluid.