2. Marine environment

2.1 General topography

Although there are considerable variations from one zone to the next, from the coast onwards, the continental shelf, then the continental slope and finally the abyssal plain can be distinguished (figure 2 ). The general slope of the continental slope is fairly gentle, around 1 to 2%, but can become steeper in submarine canyons. This general slope is nevertheless sufficient to influence multiphase flow regimes, particularly when the fluid first flows in the direction of increasing depth and then upwards towards the surface. This is known as terrain slugging.