Impact of Fluid Behavior Modification under Elevated Pressure and Temperature Conditions on Shale-Gas/Condensate Reservoir Engineering and Production Analysis

Abstract

Abstract This paper primarly focuses on the proper description of single- and multi-component hydrocarbon transport in nanoporous organic-rich shales and therefore presents the relevant issues and exploratory modeling studies to account for the effects necessary for accurate reservoir simulation. The deviation from the Darcian flow behavior of the gas/condensate transport through shale reservoirs is shown to occur mainly by alteration of fluid properties because of pore proximity effects at elevated reservoir pressure and temperature conditions although the Knudsen and Klinkenberg type corrections may involve at low pressures at later stages of hydraulically-fractured wells in shale reservoirs. A systematic methodology is presented for modification of the fluid and phase behavior relevant to transport at elevated pressure and temperature conditions. The modifications of the phase diagram, density, viscosity, and surface tension for typical hydrocarbon components and mixtures in various size pores reduced further by adsorbed components layers are compared with those of the bulk systems. Further, the role of organic connectivity in shales characterized by organic and inorganic nanopores on production from shale wells is investigated. The role and performance of isolated organics in the form of a ‘raisin-bread’ model in comparion with organics that are organized in slabs with relatively longer correlation lengths are demosntrated by simulation. The methodology for haldling of the organic connectivity and the pore-proximity effects on fluid properties provided here may be instrumental for accurate shale gas and liquids-rich shale reservoir simulation.