Understanding multimechanistic gas-water flow in fractured reservoirs: Mapping of the multimechanistic flow domain

The multimechanistic flow mechanism was proposed by Ertekin et al. in 1986. The principal hypothesis behind this mechanism was the transport of fluids under simultaneous influence of pressure and concentration gradients. In this study, we applied the multimechanistic flow concept to fractured reservoirs. We believe this application is relevant because multimechanistic flow may exist in naturally fractured gas reservoirs as well as coal seams. The development of the multimechanistic flow model, as applied to fractured reservoirs, is presented in detail in Chawath6 et al. (1996 [1]), and the underlying physics of multimechanistic flow is explained in Chawathe" et al. (1996 [2]). In this paper, we discuss identification of fractured systems undergoing multimechanistic flow. Preliminary studies indicate that multimechanistic flow results in significant increase in cumulative gas production. One of the primary observations of this study is that it is not the fracture permeability by itself, but the ratio of the fracture to matrix permeabilities that influences cumulative gas production characteristics. In conclusion, we present a multimechanistic flow map which may assist the engineer in identifying fractured systems undergoing multimechanistic flow behavior.