A dry polymer powder for use in enhanced petroleum recovery without being prehydrated before being added to water or brine to be introduced into a wellhead. The dry polymer powder consisting of at least one of a polyacrylamide, a copolymer of acrylamide and acrylic acid, a galactomannan, or cellulosic polymer or derivatives thereof, and the polymer can be crosslinked or not crosslinked, provided that if they are homo- or co-polymers of acrylic acid, they are not crosslinked. The dry polymer powder has a polymer size range distribution of 6.6% 200 mesh, and wherein the polymer size range ensures that the dry polymer powder will efficiently hydrate in the water or brine within about one minute without forming fisheyes.