Phase Behavior and Adsorption of Pure Substances and Mixtures and Characterization in Nanopore Structures by Density Functional Theory

Liu, Zhidong; Jin, Zhehui; Firoozabadi, Abbas

doi:10.2118/169819-pa

Cited by 174 publications

(115 citation statements)

References 36 publications

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“…12a). Notably, the Jin et al (2013) and Ma et al (2013) models give a very good match on the shift on critical temperature of ethane. On the other hand, none of these models provides good approximation of the shifts on critical pressures of both methane and ethane.…”

Section: Resultsmentioning

confidence: 94%

“…Devegowda et al (2012) manipulated those results to derive expressions to calculate the deviations of the critical properties of pure hydrocarbons as functions of molecular weight for slit pores with widths of 2.0, 4.0, and 5.0 nm. Ma et al (2013) and Jin et al (2013) used the same data set as Devegowda et al did with additional experimental data from Vishnyakov et al (2001) and Singh and Singh (2011) to develop models to approximate the shifts on critical properties of confined hydrocarbons. Similar to the model from Zarragoicoechea and Kuz (2004), the critical shifts of Ma et al (2013) and Jin et al (2013) are functions of pore width and type of contained fluid.…”

Section: Introductionmentioning

confidence: 99%

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Effect of Confinement on Pressure/Volume/Temperature Properties of Hydrocarbons in Shale Reservoirs

et al. 2016

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Shale reservoirs play an important role as a future energy resource of the United States. Numerous studies were performed to describe the storage and transport of hydrocarbons through ultrasmall pores in the shale reservoirs. Most of these studies were developed by modifying techniques used for conventional reservoirs. The common pore-size distribution of the shale reservoirs is approximately 1 to 20 nm and in such confined spaces that the interactions between the wall of the container (i.e., the shale and kerogen) and the contained fluids (i.e., the hydrocarbon fluids and water) may exert significant influence on the localized phase behavior. We believe this is because the orientation and distribution of fluid molecules in the confined space are different from those of the bulk fluid, causing changes in the localized thermodynamic properties.This study provides a detailed account of the changes of pressure/volume/temperature properties and phase behavior (specifically, the phase diagrams) in a synthetic shale reservoir for pure hydrocarbons (methane and ethane) and a simple methane/ethane (binary) mixture. Grand canonical Monte Carlo (GCMC) simulations are performed to study the effect of confinement on the fluid properties. A graphite slab made of two layers is used to represent kerogen in the shale reservoirs. The separation between the two layers, representing a kerogen pore, is varied from 1 to 10 nm to observe the changes of the hydrocarbon-fluid properties. In this paper, the critical properties of methane and ethane as well as the methane/ethane mixture phase diagrams in different pore sizes are derived from the GCMC simulations. In addition, the GCMC simulations are used to investigate the deviations of the fluid densities in the confined space from those of the bulk fluids at reservoir conditions. Although not investigated in this work, such deviations may indicate that significant errors for production forecasting and reserves estimation in shale reservoirs may occur if the (typical) bulk densities are used in reservoir-engineering calculations.

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Section: Resultsmentioning

confidence: 94%

Section: Introductionmentioning

confidence: 99%

Effect of Confinement on Pressure/Volume/Temperature Properties of Hydrocarbons in Shale Reservoirs

et al. 2016

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“…A significant amount of adsorption at low relative pressure (i.e., p/p 0 < 0.05) is indicative of microporosity. Hysteresis generally associated with capillary condensation occurs when the pore width exceeds a certain critical width, and it always occurs for pores wider than~4 nm [37,40,41]. The hysteresis loop in Fig.…”

Section: Adsorption Isothermsmentioning

confidence: 96%

Nanopore structure characterization for organic-rich shale using the non-local-density functional theory by a combination of N2 and CO2 adsorption

Wei

Zhang

Xiong

et al. 2016

Microporous and Mesoporous Materials

136

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“…It is well known that nanopores are widely distributed in both organic and inorganic matter in tight formations or shales (Li et al 2014). In small pores, the thermophysical properties of fluids are significantly affected by the interaction between pore surfaces and fluid molecules.…”

Section: Introductionmentioning

confidence: 99%

“…In the model, the fluid molecules were assumed spherical, interacting with each other and with the pore though square-well potentials. Li et al (2014) combined density functional theory (DFT) with the Peng-Robinson EoS to investigate the phase behavior of pure substances and mixtures in nanopores. As aforementioned, Parachor Model together with VIT method is one of promising approach to evaluate MMP in bulk phase.…”

Section: Introductionmentioning

confidence: 99%

Application of PC-SAFT Equation of State for CO2 Minimum Miscibility Pressure Prediction in Nanopores

Wang

Chen

2016

SPE Improved Oil Recovery Conference

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CO 2 miscible injection is generally one of the most efficient enhanced oil recovery (EOR) methods and widely used in the conventional oil reservoirs. The applicability of CO 2 EOR technology for unlocking the resources from unconventional tight and shale formations and the mechanisms of miscible flooding in these reservoirs still remain unclear. An important parameter used to evaluate the feasibility of CO 2 miscible flooding is the minimum miscibility pressure (MMP). Even though experimental approaches, empirical correlations and theoretical methods have performed well in measuring or predicting MMP between CO 2 and crude oil in conventional reservoirs, they may not be suitable for unconventional formations as phase behavior and MMP can be significantly affected by confinement effect in small pores (e.g., nanopores) in such formations.In this study, a new MMP prediction model based on the modified Parachor Model associated with the Perturbed-Chain Statistical Associating Fluid Theory (PC-SAFT) is developed to determine CO 2 MMP both in the bulk phase and nanopores. The Parachor Model is modified to account for the confinement effect of nanopore walls on the equilibrium interfacial tension (IFT). The Equilibrium IFT reduction in nanopores is related to a temperature-dependent and slit pore width-dependent modification term. The parameters of the new Parachor Model are determined by matching the vapor-liquid surface tension values for CH 4 , C 2 H 6 , C 3 H 8 , n-C 4 H 10 , and n-C 8 H 18 in nanopores, respectively. The prediction ability of the new model is verified by comparing the predicted MMP in the bulk phase with the results of other theoretical approaches and slim-tube experimental data. Finally, the new model is applied to estimate the MMP between Bakken oil and CO 2 stream. The effect of temperature, slit pore width, and impure components in the injected CO 2 on the MMP are also studied. The newly developed model successfully reproduces MMP in bulk phase as compared with both other methods and experimental data. The overall average absolute relative deviation (AARD) for MMP is within 8 %. The calculated equilibrium IFT for liquid-vapor phase has a good agreement with molecular simulation results. For Bakken oil-CO 2 system, if the slit pore width is larger than 10 nm, MMP is independent on pore width; otherwise, it decreases significantly with the decrease of the pore width. If pore width decreases to 3 nm, 67.5 % decrease in the IFT is observed and 23.5% reduction is achieved for MMP between Bakken oil and CO 2 stream, indicating that it is easier to reach miscibility in nanopores, and CO 2 miscible flooding might be a promising enhanced oil recovery (EOR) technology for tight oil and shale oil reservoirs. Furthermore, MMP increases with an increase of temperature in bulk phase, whereas IFT and MMP decrease with an increase of temperature in nanopores.

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Phase Behavior and Adsorption of Pure Substances and Mixtures and Characterization in Nanopore Structures by Density Functional Theory

Cited by 174 publications

References 36 publications

Effect of Confinement on Pressure/Volume/Temperature Properties of Hydrocarbons in Shale Reservoirs

Effect of Confinement on Pressure/Volume/Temperature Properties of Hydrocarbons in Shale Reservoirs

Nanopore structure characterization for organic-rich shale using the non-local-density functional theory by a combination of N2 and CO2 adsorption

Application of PC-SAFT Equation of State for CO2 Minimum Miscibility Pressure Prediction in Nanopores

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