A Streamline Approach to Retain Extensive Discrete Fracture Networks from a Detailed Static Fracture Model

When building a model of a naturally fractured reservoir, it is not sufficient to produce a highly detailed static model, it is also necessary that such a model can be flow simulated so that the production response given by the flow simulator can be compared to production history of the field. The technique that we present here takes a highly detailed static model of fractures, and identifies the fracture networks (DFNs) important for flow within the reservoir during early stages of production. This technique uses the time-offlight of streamlines to identify high conductive paths (DFNs). The extensive DFNs retained with our technique are then included onto a coarse flow simulation model by using transmissibility connections according to the source model proposed by Voelker. The later can be easily implemented in a standard commercial simulator by using pseudowells and a multiplication factor (WPIMULT in Eclipse) for their productivity index. In this paper, we illustrate our technique using a realistic static fracture model. Our technique has proven to be fast –it only requires mapping of streamlines, and computing the time of flight-, but most importantly, we were able to reproduce most important characteristic behavior of early stages of production of the reference production history just by considering the DFNs that we retained with our technique and a combination of parameters for the source model. A first approximation of the WPIMULT factor was obtained by considering the results of our sensitivity study of the parameters of the source model and its effect on production response. The results showed that besides fracture properties, WPIMULT seems to be dependent on grid coarsening, continuity of the DFN, and number of transmissibility connections considered in the source model. Introduction The state of the art in modeling naturally fractured reservoirs consist of techniques capable of building highly detailed fracture models based on realistic fracture geometry