Abstract: A novel method for breaking the viscosity of an aqueous phase thickened with preferably hydrophilic polymers in the exploration and production of mineral oil and/or natural gas is proposed. For this purpose, the breaking is carried out via the formation of a low-viscosity emulsion, with water as the continuous phase, this emulsion being formed by the addition of at least one surface-active component to a system which consists of the thickened drilling fluid and an oil phase which is crude oil present in the reservoir and/or oil introduced into the reservoir. Solubilizers between oil phase and water phase and in particular non-ionic surfactants, cationic surfactants and/or amphoteric surfactants are used as a preferred surface-active component. In addition to the surface-active component, it is possible to use further components, which are demulsifiers, non-emulsifiers, co-surfactants or surface tension modifiers.