The use of solid materials based on synthetic polymers and/or biopolymers (A) in natural gas and mineral oil extraction technology. The solid materials are produced by solubilizing at least one synthetic polymer and/or biopolymer (A), or at least one synthetic polymer and/or biopolymer (A) and at least one additive (B), in at least one substantially anhydrous chaotropic liquid (C). The solution or dispersion (AC) or (ABC) is contacted with a liquid (D1) which is miscible with the chaotropic liquid (C), but in which at least the synthetic polymer and/or the biopolymer (A) are substantially insoluble, resulting in a phase (E). The chaotropic liquid (C) is removed from phase (E) to result in a gel (G), which is impregnated with a liquid (D2). The two liquids (D1) and (D2) are removed from the gel (G) by evaporating, producing a solid material based on synthetic polymer and/or biopolymer (A).