There is provided an apparatus (30) and method for conditioning the flow of a mixed phase flow from a supply pipe (101) from a hydrocarbon well. The apparatus (30) comprises an elongate reservoir (11) having a first end for receiving a multi-phase fluid flow from the supply pipe and a second closed end, there being provided a gas outlet (02) from the upper part of the first end, a liquid separation region downstream of the first end, and a liquid outlet (12) from the lower part of the liquid separation region; and a gas-liquid mixer to which the gas and liquid outlets are connected such that the separated gas and liquid may be recombined. The reservoir (11) may accommodate surges of liquid such that the flow rate from the liquid outlet is relatively invariant over time compared to that of the flow received by the apparatus.