Abstract: A liquid/gas separator device for separating the liquid and gaseous phases of a fluid, the device having first and second vertically-disposed elongate reservoirs. The first reservoir has a first bottom orifice connected to an arrival pipe for the fluid that includes a pressure-lowering device, at least one first top orifice, and a plurality of first intermediate orifices. The first reservoir is connected to a plurality of second reservoirs via a plurality of first transfer pipes, and via at least one second transfer pipe. Each of second reservoirs has a second top orifice connected to a common gas discharge pipe, and a second bottom orifice connected to a common degassed fluid discharge pipe.