Method of adaptive separation of a mixture from gas and/or oil exploration or production, said mixture comprising a varying mixture of liquid and gaseous phases, wherein the mixture is introduced into a continuous through-flow settling vessel, said vessel provided with: an inlet for the mixture, and a gas outlet, a water outlet and an oil outlet, the outlets (5, 7, 8) being provided distant from the inlet, and the oil outlet being downstream of the water outlet, a weir downstream of the water outlet and upstream of the oil outlet, which weir functions as a barrier to a free through-flow in the vessel of the liquid phase which comprises a water phase and an oil phase, which phases (16, 18) are separated from each other by settling, the weir having a height lower than the gas outlet, and wherein the normal method of separation involves the continuous controlling of the velocity of flow through the inlet and outlets (5, 7, 8) of the vessel, so that a liquid level of the liquid phase in the vessel is maintained during operation at or below a threshold value between the height of the weir and the height of the gas outlet, and wherein the adaptive separation comprises the steps of: - determining the presence in a pipeline of an inhomogeneity in the mixture which is mainly liquid, also referred to as a slug flow, before it enters the inlet of the vessel; during a phase A which precedes the slug flow entering the vessel: - lowering the liquid level of the liquid phase in the vessel upstream of the weir to or below an adapted height lower than the threshold value; and during a subsequent phase B which includes the slug flow entering the vessel: - allowing the liquid level to rise above the adapted height in the vessel upstream of the weir, and subsequently maintaining the liquid level at or below the threshold value. an inlet for the mixture, and a gas outlet, a water outlet and an oil outlet, the outlets (5, 7, 8) being provided distant from the inlet, and the oil outlet being downstream of the water outlet, a weir downstream of the water outlet and upstream of the oil outlet, which weir functions as a barrier to a free through-flow in the vessel of the liquid phase which comprises a water phase and an oil phase, which phases (16, 18) are separated from each other by settling, the weir having a height lower than the gas outlet, and wherein the normal method of separation involves the continuous controlling of the velocity of flow through the inlet and outlets (5, 7, 8) of the vessel, so that a liquid level of the liquid phase in the vessel is maintained during operation at or below a threshold value between the height of the weir and the height of the gas outlet, - determining the presence in a pipeline of an inhomogeneity in the mixture which is mainly liquid, also referred to as a slug flow, before it enters the inlet of the vessel; - lowering the liquid level of the liquid phase in the vessel upstream of the weir to or below an adapted height lower than the threshold value; and - allowing the liquid level to rise above the adapted height in the vessel upstream of the weir, and subsequently maintaining the liquid level at or below the threshold value.