its extension to 2d and 3d exchange conditions and its validation in relation to reference simulations on finely gridded models is described hereafter heading 0043 formulation of out of equilibrium oil and gas transfers between a fracture and a non gridded matrix block transfers between a fracture continuously swept by fresh injection gas and an initially oil saturated matrix block are based on the following modelling of the physical phenomena involved a component transfer takes place through the interface between the oil and the gas so as to establish a local equilibrium between the two phases this local equilibrium is obtained instantly in relation to the time required to establish a global equilibrium between the fracture and matrix fluids by means of diffusion phenomena on block scale a molecular diffusion takes place within each phase as a result of the composition difference between the interface between phases and the phase taken as a whole because of volumetric changes within each phase the vapour liquid interface progresses swelling or moves back vaporization within the matrix medium the simplified model of these phenomena considers that a vapor liquid front exhibiting a quasi static equilibrium at the interface is established from the initial time and progresses at a velocity controlled by.