1. A method for oil-related exploitation by simulating a geological formation of a fluvial zone comprising: providing a gradient of flow speed for the fluvial zone, defining a spatial model of the fluvial zone comprising at least one upstream region and one downstream region, on the basis of the gradient of flow speed, simulating the displacement of particles in the spatial model by superimposing: a deterministic term defined on the basis of the gradient of flow speed, and a stochastic term parametrized at least by the gradient of flow speed, wherein a plurality of zones of the spatial model is defined between the upstream region and the downstream region, and in which a parametrization of the stochastic term in a first zone differs from a parametrization of the stochastic term in at least one second zone wherein a trajectory of a channel corresponding to mean direction of flow extending from the upstream region to the downstream region is represented; predicting an area in the fluvial zone more likely to contain a hydrocarbon deposit based on the simulating of the geological formation; and installing a hydrocarbon exploitation facility and producing hydrocarbons in the area more likely to contain the hydrocarbon deposit, based on a result of the simulation.