Pore structure characterization and pore fluid assessment play an essential role in unconventional shale gas evaluation. However, the determination of petrophysical parameters, especially effective porosity for shale is challenging due to the impact of clay bound water (CBW), the tight texture and the complicated pore structure. In particular, no such porosimetric technique is able to...
Surfaces may influence elastic and plastic properties of nanostructured materials. Nanoporous gold (npg), as one of the most suitable probes for such effects, was mechanically deformed in an electrochemical environment allowing in-situ modification, i.e. electric charging as well as electrosorption of ion species, while the mechanical loading took place. The change in stiffness in the regime...
Numerical modeling has been an increasingly important approach for better understanding fluid flow and transport phenomena in organic-rich, nanoporous shale. However, deployment of numerical models in the context of nanoporous shale is challenging because of the multi-length-scale nature of the porosity in shale, where pore sizes can range between the nanoscale (~ $10^{-9}$ m) and microscale...
Capillary condensation in a nano-porous material can induce high local stresses affecting its transport, tribological and rheological properties, promoting cracking and can eventually lead to failure of the material.
However it is a non-trivial problem to determine the capillary stress field in realistic 3D structures covering the entire range of degree of liquid saturation.
We propose a...
Methane hydrate is a non-stoichiometric crystalline structure in which water molecules form hydrogen-bonded cages with methane molecules inside. Abundant methane hydrate resources are present on Earth, especially in various mineral porous media (e.g., clays, coal, shale, permafrost and sea-floor).[1] Understanding the dynamics and thermodynamics of methane hydrate confined in porous media has...
A phase diagram of methane+n-butane mixture is investigated by the means of molecular dynamics (MD) simulations. The system exhibits retrograde condensation behavior above 191 K in some range of methane molar fractions. A vapor-liquid equilibrium curve for mixtures is calculated with TraPPE-UA united-atom forcefield [1], TraPPE-EH [2] and OPLS-AA [3,4] all-atom forcefields. The forcefields...
Commonly, studies on imbibition focus on porous matrices with bicontinuous morphology that contain spongy pore systems with neck-node morphologies. In this context, much attention has been paid to cooperative imbibition phenomena such as imbibition front broadening, viscous fingering, or avalanche-like relaxations of the imbibition fronts, which occur in systems of hydraulically coupled pores....
Adsorption-induced deformation has been found to manifest in numerous natural and engineering processes, e.g., drying of concrete, water-actuated movement of non-living plant tissues, swelling of coal and shale, etc. [1]. The driving force for the deformation is solvation pressure – the pressure that a fluid adsorbed in a nanopore exerts on the pore walls. Solvation pressure can be calculated...
MIL-53 is a MOF porous structures which exhibits very pronounced flexibility. As a consequence, adsorption of CO2 causes its reversible structural transformation, induced by the host-guest interactions. Here, we present detailed molecular modeling study of adsorption of CO2 and CH4 in the intermediate structures of the MOF. We use 20 intermediate structures, between the open pore one and the...
Hydraulic fracturing is an effective method to improve oil recovery by injecting massive fracturing fluid to create complex fracture networks. After that, the well is commonly shut down for a period to promote water uptake and appropriate shut-time is of vital importance. One effective way to predict shut-in time is to combine experimental results of spontaneous imbibition (SI) and...
Metal organic frameworks (MOFs) consist of metal oxide cores linked by multifunctional organic linkers, forming crystal-like structures with well-defined pore size. They are highly promising materials in a large variety of applications including gas storage, solvent separation, drug delivery, and catalysis. The guest-host interaction is of key importance for all these applications and...
Three-dimensionally ordered mesoporous (3DOm) carbon is produced by negative templating of spherical silica nanoparticles [1]. The final product represents a periodic nanostructure with spherical pores interconnected by openings. These materials are promising for application in separation and purification processes as adsorbents, and for natural gas storage of methane in the form of hydrates...
In contrast to the conventional reservoirs, shale reservoirs embody micro-pores developed from inorganic minerals and nano-pores developed from organic matters, which can both exert an important influence on two-phase flow properties. Through a bimodal pore-size distribution (PSD) in whole shale system verified by nitrogen absorption tests may be assumed as the Gaussian mixtures, the random...
Nano-Pore-throat are dominantly developed in shale，The flow of gas in the nano pore throat is different from that of the conventional pore throat. Shale flow has micro scale effects, and the flow is more complex, In order to establish the flow model and flow equation which can be used in the analysis of shale gas flow, In this paper, based on the single nanotube model , Combined with the...
Molecular dynamics study of the glass transition process in metallic glasses is performed. As an example, the liquid aluminum film is taken. The embedded atom method potential is used at the simulation of isobaric cooling [1]. There is a number of glass transition criteria: the decrease of the specific heat of material (calorimetric criterion) [2], the splitting of the second peak of the pair...
