[SY-F14] Transport Properties Of Fluid Mixtures In Micro- And Mesoporous Kerogen Membranes
With the exhaustion of conventional resources, the production of gas from organic-rich shales has encountered a rising interest over the last 15 years. In such resources, gas is trapped in nodules of organic matter scattered in an inorganic matrix mostly constituted of quartz, clays, and calcite. Nodules represent only few percentages of the total volume of shales and result from a maturation process during the burial stage. These nodules of organic matter contain mostly kerogen that acts as a source, but also as a container of hydrocarbons. Various forms were reported differentiating to each other by their origin, their maturity, and sediment history, which affects, for example, their chemical composition, their density, and the porosity. A common feature of kerogens is their multi-scale porous network with pore sizes ranging from micropores (<2 nm) to macropores (>50 nm). Structure and connectivity of pores greatly affect the materials permeability. In porous structures where the flow is limited by micropores (e.g., pore throats), very low permeabilities are observed.
Despite the important development of shales, fluid flow mechanisms within kerogen matrix remains poorly understood. While experimental characterization remains difficult, molecular dynamics simulations were proven very useful to characterize transport mechanisms within kerogen membranes. The aforementioned studies staid limited to microporous systems, while mass transfer originating from small pores and transiting to larger pores, fractures, and production wells is a multi-scale mechanism. In this work, we designed and developed molecular simulation tools to capture both microporosity and mesoporosity of kerogen through the aggregation and the spatial arrangement of smaller basic units in order to generate representative molecular structures. From those models, we investigated by molecular dynamics simulations how the nature (i.e., maturity and sediment origin) and the chemical composition influence both the porous network and the related physical and transport properties of fluid mixtures (e.g., selectivity, phase coexistence, diffusivity) in kerogen.
This method and findings underscore the importance of accounting for both micro- and mesoporosity to accurately model fluid transport in kerogen.
Despite the important development of shales, fluid flow mechanisms within kerogen matrix remains poorly understood. While experimental characterization remains difficult, molecular dynamics simulations were proven very useful to characterize transport mechanisms within kerogen membranes. The aforementioned studies staid limited to microporous systems, while mass transfer originating from small pores and transiting to larger pores, fractures, and production wells is a multi-scale mechanism. In this work, we designed and developed molecular simulation tools to capture both microporosity and mesoporosity of kerogen through the aggregation and the spatial arrangement of smaller basic units in order to generate representative molecular structures. From those models, we investigated by molecular dynamics simulations how the nature (i.e., maturity and sediment origin) and the chemical composition influence both the porous network and the related physical and transport properties of fluid mixtures (e.g., selectivity, phase coexistence, diffusivity) in kerogen.
This method and findings underscore the importance of accounting for both micro- and mesoporosity to accurately model fluid transport in kerogen.