Chromatographic separation and liquid drop-out in unconventional gas reservoirs

Many analytical/semi-analytical models available for gas transport in unconventional reservoirs are based on single component or binary mixtures. In this work, we demonstrate the effect of including heavier fractions in modelling gas transport when they are present, which is relevant in prediction of pressure decline, produced gas composition and natural gas liquids (NGLs) yields. Moreover, we demonstrate that gas composition at the wellbore can be significantly influenced by a balance between viscous and diffusion fluxes, and we highlight the relevant transport mechanisms to be considered when modelling multicomponent gas flow in tight reservoirs.