Laboratory Measurement of Sorption Isotherm Under Confining Stress With Pore-Volume Effects

Santos, José Maria Campos dos; Akkutlu, I. Yücel

doi:10.2118/162595-pa

Cited by 35 publications

(14 citation statements)

References 12 publications

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“…This observation was also reported by Tan and Gubbins for methane adsorbed in carbon micro pores44 and Liu et al for methane adsorbed in shale45. This can be explained by the fact that the sorption potential overlaps more intensely in a smaller pore size, thus the adsorption positions get saturated at lower pressure.…”

Section: Resultssupporting

confidence: 82%

Research of CO2 and N2 Adsorption Behavior in K-Illite Slit Pores by GCMC Method

Chen

Zhang

Han

et al. 2016

Sci Rep

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Understanding the adsorption mechanisms of CO2 and N2 in illite, one of the main components of clay in shale, is important to improve the precision of the shale gas exploration and development. We investigated the adsorption mechanisms of CO2 and N2 in K-illite with varying pore sizes at the temperature of 333, 363 and 393 K over a broad range of pressures up to 30 MPa using the grand canonical Monte Carlo (GCMC) simulation method. The simulation system is proved to be reasonable and suitable through the discussion of the impact of cation dynamics and pore wall thickness. The simulation results of the excess adsorption amount, expressed per unit surface area of illite, is in general consistency with published experimental results. It is found that the sorption potential overlaps in micropores, leading to a decreasing excess adsorption amount with the increase of pore size at low pressure, and a reverse trend at high pressure. The excess adsorption amount increases with increasing pressure to a maximum and then decreases with further increase in the pressure, and the decreasing amount is found to increase with the increasing pore size. For pores with size greater larger than 2 nm, the overlap effect disappears.

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Section: Resultssupporting

confidence: 82%

Research of CO2 and N2 Adsorption Behavior in K-Illite Slit Pores by GCMC Method

Chen

Zhang

Han

et al. 2016

Sci Rep

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“…Total sorption measurement is typically done including the combined effect of these components (Kang et al, 2010;Santos and Akkutlu, 2012). Currently we cannot determine the adsorbed and dissolved gas amounts separately in the laboratory.…”

Section: Case 1 -Estimation Of Gas-in-place In Nanoporous Shale Gas Rmentioning

confidence: 99%

Pore-Size Dependence of Fluid Phase Behavior and the Impact on Shale Gas Reserves

Didar

Akkutlu

2013

Unconventional Resources Technology Conference, Denver, Colorado, 12-14 August 2013

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Because of commodity pricing, the production from organic rich shales such as Barnett, Woodford, Eagle Ford and Marcellus has shifted significantly away from the dry natural gas window into the more profitable condensate and liquid hydrocarbon (oil) windows. The current production practices, however, are based mainly on field experience of the operators and far from being a methodological approach for an optimized production. This is mainly due to the fact that our understanding of condensation, capillarity and multi-phase flow dynamics in shale reservoirs is at an infancy stage. It is currently not known, for example, if and where the condensation takes place in the reservoir, and what is the impact of the shale matrix on the this phenomenon. In this paper we argue that answering these questions using conventional laboratory measurement techniques is a difficult task because the fluid properties and the phase behavior of the hydrocarbons could be influenced by the nanoporous nature of these rocks.Monte Carlo simulations are conducted to investigate pure hydrocarbon vapor-liquid coexistence and critical properties under confinement. The results show a pore size dependence of these thermo-physical properties. Phase diagrams generated using ternary (C 1 , C 4 , and C 8 ) mixtures under reservoir conditions show a two-phase envelop shift due to pore size dependence. We show the importance of the results performing a shale gas inplace calculation using Ambrose's equation where the equation of state parameters, z-factor, gas formation volume factor, and adsorbed-phase density values are all adjusted for a range of effective pore size. The corrections on the free and the sorbed gas in-place estimates are significant. Furthermore, we predicted reserves from wet gas, condensate, and volatile oil reservoirs using compositional flow simulation. It is shown that the liquid production from nanoporous rocks is enhanced due to a significant decrease in the bubble point and dew point pressures.

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“…They serve as means of transporting and storing compressed gas. In kerogen, the voids are made up of organic nanopores with the capacity to store significant quantities of gas in the sorbed form because their nanometer size is associated with a significant surface area [ 1 , 2 , 3 , 4 , 5 , 6 , 7 , 8 , 9 ]. As source rocks are exposed to various types of stimulation procedures, the natural gas is subject to continuous expansion in the larger pores.…”

Section: Introductionmentioning

confidence: 99%

Effect of Kerogen Thermal Maturity on Methane Adsorption Capacity: A Molecular Modeling Approach

2020

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The presence of kerogen in source rocks gives rise to a plethora of potential gas storage mechanisms. Proper estimation of the gas reserve requires knowledge of the quantities of free and adsorbed gas in rock pores and kerogen. Traditional methods of reserve estimation such as the volumetric and material balance approaches are insufficient because they do not consider both the free and adsorbed gas compartments present in kerogens. Modified versions of these equations are based on adding terms to account for hydrocarbons stored in kerogen. None of the existing models considered the effect of kerogen maturing on methane gas adsorption. In this work, a molecular modeling was employed to explore how thermal maturity impacts gas adsorption in kerogen. Four different macromolecules of kerogen were included to mimic kerogens of different maturity levels; these were folded to more closely resemble the nanoporous kerogen structures of source rocks. These structures form the basis of the modeling necessary to assess the adsorption capacity as a function of the structure. The number of double bonds plus the number and type of heteroatoms (O, S, and N) were found to influence the final configuration of the kerogen structures, and hence their capacity to host methane molecules. The degree of aromaticity increased with the maturity level within the same kerogen type. The fraction of aromaticity gives rise to the polarity. We present an empirical mathematical relationship that makes possible the estimation of the adsorption capacity of kerogen based on the degree of polarity. Variations in kerogen adsorption capacity have significant implications on the reservoir scale. The general trend obtained from the molecular modeling was found to be consistent with experimental measurements done on actual kerogen samples. Shale samples with different kerogen content and with different maturity showed that shales with immature kerogen have small methane adsorption capacity compared to shales with mature kerogen. In this study, it is shown for the first time that the key factor to control natural gas adsorption is the kerogen maturity not the kerogen content.

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Laboratory Measurement of Sorption Isotherm Under Confining Stress With Pore-Volume Effects

Cited by 35 publications

References 12 publications

Research of CO2 and N2 Adsorption Behavior in K-Illite Slit Pores by GCMC Method

Research of CO2 and N2 Adsorption Behavior in K-Illite Slit Pores by GCMC Method

Pore-Size Dependence of Fluid Phase Behavior and the Impact on Shale Gas Reserves

Effect of Kerogen Thermal Maturity on Methane Adsorption Capacity: A Molecular Modeling Approach

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