The present invention relates to filamentous polymer particles useful in oil, condensate or gas recovery from subterranean locations as hydraulic fracturing fluids, diverting fluids, fluids that make it possible to improve the distribution and the flow profiles of the fluids or products injected (referred to as conformance fluids) or permeability control fluids, sand control gravel pack placement fluids, acid fracturing fluids, and the like. These fluids are stimulation fluids injected in wells which serve also as producing wells for the hydrocarbons initially present in the subterranean formations.