Method for breaking the viscosity of polymer-thickened aqueous systems for mineral oil and natural gas exploration

摘要

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. With the aid of this method, with the simultaneous presence of an oil phase, the aqueous phase can be displaced as a low-viscosity system and finally discharged at the surface, extremely effective cleaning of the well being associated therewith. With regard to the cost-efficiency and from an environmental point of view, the use of chemicals can be completely dispensed with.