The effect of Knudsen diffusion and adsorption on shale transport in nanopores

Chen, Jie; Hou, Jiangyong; Wang, Rui; Hui, Yi

doi:10.1177/1687814017721858

Cited by 9 publications

(4 citation statements)

References 30 publications

(38 reference statements)

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“…Extensive research shows that these phenomena affect apparent permeability and make the shale flow calculation a complex multi-scale problem (Shabro et al, 2011;Islam and Patzek, 2014;Javadpour et al, 2007;Chen et al, 2017;Zhang et al, 2015). Our focus in this research is recovery improvement associated with permeability enhancement due to macro-scale thermal crack stimulation while micro-and nano-scale gas flow is not yet taken into account.…”

Section: A C C E P T E D Accepted Manuscriptmentioning

confidence: 99%

Thermal cooling to improve hydraulic fracturing efficiency and hydrocarbon production in shales

Enayatpour

Oort

Patzek

2019

Journal of Natural Gas Science and Engineering

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Unconventional hydrocarbon reserves contained in oil and gas shale formations are proving themselves to be abundant sources of current and future energy supply, unlocked through the technologies of horizontal drilling and hydraulic fracturing. Despite the various technology improvements that have buoyed the "shale revolution" in the last decade, there remain very significant opportunities to further improve hydrocarbon recovery from shales by making hydraulic fracturing more efficient. In this paper, we look into the possibility of stimulating a rock matrix to a higher degree with hydraulic fractures by deliberately cooling down the rock. Cooling reduces in-situ thermal stress, which lowers initiation and propagation pressures of hydraulic fractures. Moreover, when a laterally confined solid undergoes temperature reduction induced by cooling, a thermal stress gradient is developed in the solid body. We perform sensitivity analyses to show that in an in-homogenous shale, this thermal stress gradient can lead to differential contraction of its various mineralogical constituents, which in turn may create thermal cracks. The opening of such cracks increases shale permeability and provides additional pathways for the flow of hydrocarbons, thereby enhancing productivity.Here, we solve the coupled equations of stress, heat transfer and flow using finite element techniques for hydraulic stimulation amplified by cooling. It is shown that thermal cracks in tight formations induced by thermal cooling have the potential to improve the productivity of horizontal wellbores placed in shale by an estimated 16% for the case of methane gas flow through thermally stimulated shale of micro-darcy permeability.

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Section: A C C E P T E D Accepted Manuscriptmentioning

confidence: 99%

Thermal cooling to improve hydraulic fracturing efficiency and hydrocarbon production in shales

Enayatpour

Oort

Patzek

2019

Journal of Natural Gas Science and Engineering

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“…It is of great relevance for important technical developments of the last century, like catalysts (Satterfield 1970) and fuel cells (Pant et al 2012), but also for petrochemistry (e.g. shale gas extraction (Chen et al 2017)) and space sciences (e.g. outgassing of volatiles from comets and other bodies (Gundlach et al 2011, Skorov et al 2011, Schweighart et al 2021, Haack 2022).…”

Section: Introductionmentioning

confidence: 99%

Validation of gas flow experiments for porous media by means of computer simulations

Laddha

Macher

Kargl

et al. 2023

Meas. Sci. Technol.

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A profound understanding of gas flow in porous media is of great interest for various technological and scientific fields. Its investigation by laboratory measurements, however, poses several challenges. In particular, the determination of macroscopic flow parameters from pressure and gas flow measurements is prone to various error influences, some of which are very difficult to analyze experimentally. Computer simulations are a solution in this context as they facilitate modifications of the underlying geometry and boundary conditions in a flexible way. Here we present a simulation framework for the analysis of a recent experiment for determining the Knudsen diffusion coefficient and viscous permeability of various porous granular materials. By combining the finite element method with analytical models and other numerical methods, we were able to identify previously neglected physical effects that increase the uncertainty of the measurements. In particular, the porosity increase due to finite sample dimensions, in a layer of about a grain diameter thickness near the container wall, creates a deviation of the measured pressure gradient. This deviation amounts to ca. 5% for a sample width of about 100 grains and a porosity of 0.5, and is indirectly proportional to the porosity. The second most prominent error source, the sample support sieve, causes a slight constriction of the flow volume. Simulations of this effect show an error around 4-7%, dependent on the grain size. Based on these findings we recommend an overall sample dimension of 100 grains or larger. As an example of failures of the sample homogeneity, we elaborate how channels through the sample influence the flow properties. Respective suggestions for keeping all discussed effects negligible are discussed in detail. Our methodology demonstrates how the combination of finite element computations with analytical representations of the involved macroscopic parameters can assess the validity and accuracy of laboratory experiments.

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“…Gas transport through porous materials can be controlled by various mechanisms. In pores with sizes larger than the adsorbed gas molecules, the diffusion process will occur mainly in accordance with the Knudsen mechanism in which the molecules collide with the pore walls 58 . In pores with comparable or smaller sizes than the adsorbate diameter, the gas will move both through the collisions of molecules with pore walls, and along the sorbent surface where gas transport is driven by surface energy heterogeneity.…”

Section: Resultsmentioning

confidence: 99%

Effect of porous structure of coal on propylene adsorption from gas mixtures

Wojtacha‐Rychter

Howaniec

Smoliński

2020

Sci Rep

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This paper addresses the issue of the sorption process on coal concerning propylene released from the source of coal heating in the deposit. In this study, the interaction between Polish coals and propylene molecules, as well as three other hydrocarbons (ethylene, ethane, and propane) with the application of a fixed-bed column, was investigated. The experimental results show that propylene adsorption was measurable under the experimental conditions. The differences in the amount of adsorbed propylene were predominately caused by various gas diffusion rates within the pore network associated with the molecular sieving effect. According to the experimental results, the influence of mesopores on propylene adsorption was significantly stronger than the share of micropores of the explored coals. The column tests demonstrated that the largest amount of propylene was adsorbed by coal with the highest value of pore diameter (6.48 nm) determined by nitrogen adsorption at 77 K. Under the experimental conditions, the influence of other hydrocarbons and a surface area on the quantity of the adsorbed gas was unnoticeable. This study provides an understanding of the behavior of some of the fire gases during the flow of the mixture through a heterogeneous structure of coal in the mine environment. The sorption of gases from multi-component mixture released during the selfheating of coal on carbon materials such as bituminous and lignite coals is poorly understood which provides the rationale for the topic of this work.

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The effect of Knudsen diffusion and adsorption on shale transport in nanopores

Cited by 9 publications

References 30 publications

Thermal cooling to improve hydraulic fracturing efficiency and hydrocarbon production in shales

Thermal cooling to improve hydraulic fracturing efficiency and hydrocarbon production in shales

Validation of gas flow experiments for porous media by means of computer simulations

Effect of porous structure of coal on propylene adsorption from gas mixtures

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