The Influence of Nanoporosity on the Behavior of Carbon-Bearing Fluids

Abstract

david cole and alberto striolo IntroductionPorosity and permeability are key variables linking the origin, form, movement, and quantity of carbon-bearing fluids that collectively dictate the physical and chemical evolution of fluid-gas-rock systems. 1 The distribution of pores, pore volume, and their connectedness vary widely, depending on the Earth material, its geologic context, and its history. The general tendency is for porosity and permeability to decrease with increasing depth, along with pore size and/or fracture aperture width. Exceptions involve zones of deformation (e.g. fault or shear zones), regions bounding magma emplacement and subduction zones. Pores or fractures display three-dimensional hierarchical structures, exhibiting variable connectivity defining the pore and/or fracture network. [2][3][4][5] This network structure and topology control: (1) internal pore volumes, mineral phases, and potentially reactive surfaces accessible to fluids, aqueous solutions, volatiles, inclusions, etc. [6][7][8] ; and(2) diffusive path lengths, tortuosity, and the predominance of advective or diffusive transport. [9][10][11][12] For solids dominated by finer networks, transport is dominated by slow advection and/or diffusion. [13][14][15][16] Despite the extensive spatial and temporal scales over which fluid-mineral interactions can occur in geologic systems, interfacial phenomena including fluids at mineral surfaces or contained within buried interfaces such as pores, pore throats, grain boundaries, microfractures, and dislocations (Figure 12.1) impact the nature of multiphase flow and reactive transport in geologic systems. 13,[17][18][19][20][21] Complexity in fluid-mineral systems takes many forms, including the interaction of dissolved constituents in water, wetting films on mineral surfaces, adsorption of dissolved and volatile species, the initiation of reactions, and transport of mobile species. [22][23][24] Direct observations and modeling of physical (transport) and chemical properties (reactivity) and associated interactions are challenging when considering the smallest length scales typical of pore and fracture features and their extended three-dimensional network structures. 25,26 The various void types and their evolution during reaction with fluids are critically important factors controlling the distribution of the fluid-accessible pore volume, flow dynamics, fluid retention, chemical reactivity, and contaminant species transport. [27][28][29][30][31][32] While fracture-dominated flow can be volumetrically dominant in shallow crustal settings 358 https://www.cambridge.org/core/terms.

Effects of water on the stochastic motions of propane confined in MCM-41-S pores

“…We note that in our experiments, confined propane remains in the vapor phase even at the lower temperatures probed. The effect of confinement due to the MCM-41-S pores seems to correspond to an increase in pressure, which would imply an increase in density for the confined fluid, consistent with many simulation results 47 .…”

Quantifying Pore Width Effects on Diffusivity via a Novel 3D Stochastic Approach with Input from Atomistic Molecular Dynamics Simulations

“…Due to the significantly small scale of the pores often found in shale formations, but also in engineering materials such as catalysts, atomistic molecular dynamics and Monte Carlo simulations (MD and MC) have been widely used to quantify fluid transport through narrow pores as well as fluid structure and preferential adsorption. 18 The atomistic simulations allow the user to define 1) the chemical composition of the pores, 2) their shape and size, 3) the fluids and mixtures that fill the pores, and 4) conditions such as temperature and pressure. For example, Sui et al studied adsorption and transport of methane in dry and water-wet montmorillonite clays and found that the methane self-diffusion coefficient increases rapidly as the pore size increases.…”

Factors Governing the Enhancement of Hydrocarbon Recovery via H2S and/or CO2 Injection: Insights from a Molecular Dynamics Study in Dry Nanopores

“…9 For these strategies to be fully optimised, it is important to understand, and ultimately control the molecular mechanisms that are responsible for rock-fluid interactions, inclusive of fluid sorption, migration, and fixation. 10 We consider here enhanced oil recovery (EOR). EOR methods commonly used include water, gas, and surfactant injection.…”

“…CO 2 injection into geological formations has received much attention, − sometimes as a long-term storage opportunity, whereas in some other cases, CO 2 has been injected in oil and gas fields to attempt to simultaneously achieve enhanced hydrocarbon recovery and CO 2 sequestration . For these strategies to be fully optimized, it is important to understand and ultimately control the molecular mechanisms that are responsible for rock–fluid interactions, inclusive of fluid sorption, migration, and fixation …”