There is provided a pressure oscillation damper in order to reduce the level of the pressure oscillations by the use of for a fluid extraction system. The pressure oscillation damper comprises a wall enclosing a main volume, at least two inlets, arranged in the wall and adapted to be connected to fluid extraction units, at least two outlets, arranged in the wall and adapted to be connected to pumping units, and at least one flexible member, arranged in the first volume so as to divide the first volume into at least two secondary volumes, each secondary volume forming a channel between the at least one inlet and at least one outlet, the flexible member being configured to bend toward a secondary volume having a lower pressure. Fig. 4a
