Methane/ethane adsorption behavior in shale nanopore systems with mesopores and micropores: Evaluating micropore contribution

IF 2.8 3区工程技术 Q3 CHEMISTRY, PHYSICAL

Fluid Phase Equilibria Pub Date : 2024-12-25 DOI:10.1016/j.fluid.2024.114323

Wuquan Li , Jinrong Cao , Yunfeng Liang , Yoshihiro Masuda , Takeshi Tsuji , Kohei Tamura , Tomoaki Ishiwata , Daisuke Kuramoto , Toshifumi Matsuoka

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引用次数: 0

Abstract

Shale gas has garnered significant attention as a clean and high-quality fuel resource. Shale formations exhibit broad pore size distributions, with micropores (< 2 nm) and mesopores (2–50 nm), showing different gas sorption behaviors. The sorption behavior in kerogen nanopore systems with interconnected micropores and mesopores remains poorly understood. This study introduces three kerogen nanopore systems—low-density, middle-density, and high-density—each featuring a 7.5-nm mesopore and numerous micropores. Using Grand Canonical Monte Carlo (GCMC) simulations, the sorption behaviors of pure CH₄, C₂H₆, and their mixture (9:1) across a range of pressures (1 MPa to 13 MPa) and temperatures (313.15 K, 323.15 K, and 333.15 K) were investigated. The study identified three Zones: Zone I for the free gas phase, Zone II for adsorption in mesopores, and Zone III for absorption in micropores. The sorption isotherms were calculated by integrating the adsorption amounts, normalized by measured pore volume in the mesopore domain, and absorption amounts, normalized by total organic content. The calculated excess sorption isotherms across different kerogen nanopore systems aligned with experimental results, allowing us to estimate the micropore contribution. We calculated the actual density profiles and estimated the adsorption density in micropores and those on mesopore walls, which can be used for field applications. The selectivity in three zones was compared across three kerogen nanopore systems, showing that it was not so significantly influenced by the pore geometry at all temperatures and pressures. The absolute absorption in micropores and the micropore contribution to the total absolute sorption (in percentage) align consistently with micropore volume across different kerogen nanopore systems, revealing a linear relationship with micropore volume. This research provides recommendations for laboratory experiments and offers valuable insights into the microscopic distribution of shale gas in nanopore systems, emphasizing the significance of micropores in addition to mesopores.

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页岩中孔和微孔纳米孔系统对甲烷/乙烷的吸附行为：微孔贡献的评价

页岩气作为一种清洁、优质的燃料资源受到了广泛关注。页岩储层孔径分布广泛，微孔(<；2 nm)和中孔（2 ~ 50 nm），表现出不同的气体吸附行为。具有微孔和介孔相互连接的干酪根纳米孔系统的吸附行为尚不清楚。本研究介绍了低密度、中密度和高密度三种干酪根纳米孔系统，每一种系统都具有一个7.5 nm的介孔和许多微孔。采用大正则蒙特卡罗（GCMC）模拟研究了纯CH4、C2H6及其混合物（9:1）在压力（1 MPa ~ 13 MPa）和温度（313.15 K、323.15 K和333.15 K）范围内的吸附行为。研究确定了三个区：I区为自由气相区，II区为介孔吸附区，III区为微孔吸附区。吸附等温线是通过对吸附量和吸附量的积分来计算的，吸附量是通过测量中孔域的孔隙体积来归一化的，吸附量是通过总有机含量来归一化的。计算的不同干酪根纳米孔系统的过量吸附等温线与实验结果一致，使我们能够估计微孔的贡献。我们计算了实际密度分布，并估计了微孔和中孔壁上的吸附密度，可用于现场应用。比较了三种干酪根纳米孔体系在三个区域的选择性，结果表明，在所有温度和压力下，孔隙几何形状对选择性的影响并不明显。在不同的干酪根纳米孔体系中，微孔的绝对吸收率和微孔对总绝对吸收率的贡献（以百分比计）与微孔体积一致，显示出与微孔体积的线性关系。该研究为实验室实验提供了建议，并为页岩气在纳米孔系统中的微观分布提供了有价值的见解，强调了微孔和介孔的重要性。

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来源期刊

Fluid Phase Equilibria 工程技术-工程：化工

CiteScore

5.30

自引率

15.40%

发文量

223

审稿时长

53 days

期刊介绍： Fluid Phase Equilibria publishes high-quality papers dealing with experimental, theoretical, and applied research related to equilibrium and transport properties of fluids, solids, and interfaces. Subjects of interest include physical/phase and chemical equilibria; equilibrium and nonequilibrium thermophysical properties; fundamental thermodynamic relations; and stability. The systems central to the journal include pure substances and mixtures of organic and inorganic materials, including polymers, biochemicals, and surfactants with sufficient characterization of composition and purity for the results to be reproduced. Alloys are of interest only when thermodynamic studies are included, purely material studies will not be considered. In all cases, authors are expected to provide physical or chemical interpretations of the results. Experimental research can include measurements under all conditions of temperature, pressure, and composition, including critical and supercritical. Measurements are to be associated with systems and conditions of fundamental or applied interest, and may not be only a collection of routine data, such as physical property or solubility measurements at limited pressures and temperatures close to ambient, or surfactant studies focussed strictly on micellisation or micelle structure. Papers reporting common data must be accompanied by new physical insights and/or contemporary or new theory or techniques.