A method displacing a fluid and simultaneously gas enriching a liquid cell culture medium with a gas. The method includes injecting a controlled volume of a gas or gas mixture into a one chamber by using a gas flow controller, the injection taking place through a gas inlet into a volume of liquid. This injection produces bubbling and agitation of the volume of liquid; a build-up of gas or gas mixture due to buoyancy in a hermetic space formed by the volume of liquid and the chamber, and a pressure increase in the chamber until a sufficient controlled pressure is reached of less than or equal to 10 bar. This increase displaces the volume of liquid by a fluid outlet connecting the volume of liquid to the exterior of the chamber. Also provided are a device implementing the method and a cell culture system in a multi-well culture plate.