The oil-in-water (O/W) and water-in-oil (W/O) emulsions are two common types of emulsions found in oil production industry. While stable O/W may be beneficial in transporting crude oil, stable W/O poses a flow assurance problem that leads to disruptions and losses in oil production line. This study examines the behaviour of both types of emulsion (40:60, 50:50 and 60:40 water-oil emulsion, vol. basis) subjected to 3/4D, 1/2D and 1/4D orifices within a pipeline. The study confirms that oil and water may form emulsion with only mechanical agitation and dynamic flow in the pipeline and without the presence of any emulsifying agent. The flow rate and the velocity of all emulsions were found to drop with the reduction of orifice diameter. © 2018 The Authors, published by EDP Sciences.