The residence time distribution method is used largely for modelling classical chemical engineering vessels and reactors. The classical chemical engineering approach may be adapted for oil field tracer experiment interpretations. Some attempts have been made using the residence time distribution software (DTSpro) to verify how it can be used for non-boundary systems and low tracer recovery. In practice, the software package may be used but it is not well adapted to the problem. The elementary bricks available are representative of simple flow: dispersive flow and dispersive flow exchanging with the porous zone of lower velocity, but the parameters are not directly correlated with the usual parameters used by oilfield engineers. Moreover, the artifact used to take into account the loss of tracer is complex; it is not recommended for such an application. On the other hand, the recent approach of the compartmental model derived from both CFD and residence time distribution is promising. It consists of structural and functional descriptions of the studied structure (CFD is only a structural description with a mesh and DTSpro is used as a functional description of the structure with a network of elementary behaviours).

Figure 122 shows an academic example of such a model. The advantage of such a model is that it is derived from results from several models (PORO for the streamline network, CFD, information about fracture). In a first step, the user should define an elementary ‘slice’ based on the internal structure of the oilfield, the exchange flow of major importance (radial dispersion, convection) and the boundary layer continuity rules. It is then necessary to calculate the flows
between the different parts and the number of slices simultaneously by an iterative process and by fitting the tracer response.