Quantification of organic and inorganic hydrogen in mudstones: a novel approach using the difference between organic-rich and organic-free mudstones during pyrolysis process

IF 2 3区地球科学 Q3 GEOSCIENCES, MULTIDISCIPLINARY

Frontiers in Earth Science Pub Date : 2024-07-31 DOI:10.3389/feart.2024.1421404

Pengyan Du, Jingong Cai, Huidong Li, Xuejun Zhang, Juan Wang, Liping Yang, Yanzhong Zhen

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Abstract

Whether mudstone is rich in or free of organic matter has a great influence on the occurrence of water. Comparing different types of water in organic-rich and organic-free mudstones is helpful for further understanding the role of water in hydrocarbon generation. Thermogravimetric analysis (TGA) and differential thermal analysis (DTA) combined with mass spectrometry (MS) afford the opportunity to identify the mass change, reactions and products of the sample in a real-time monitored heating process. This study compared the pyrolysis characteristics of an organic-rich mudstone (CN1) and an organic-free mudstone (CW1) by using the TGA/DTA-MS method to estimate the content of different types of H2O and CO2 in organic-rich mudstones. The results show that the mass changes in CN1 and CW1 can be divided into the three thermogravimetric (TG) stages of 0°C–200°C, 200°C–650°C, and 650°C–900°C, while the peak temperatures of H2O and CO2 obtained through MS are different for CN1 and CW1. The differences in mineral components and organic matter between CN1 and CW1 suggest that the MS peaks of H2O and CO2 in CW1 are mainly influenced by clay and carbonate minerals, and that those of CN1 are also influenced by organic matter. In addition, quantification equations for CO2 and H2O contents from both the organic and inorganic origin of the organic-rich mudstone can be established by using the MS peak area of CO2 and H2O, mass loss in TGA and the mineral composition of the organic-free mudstone. This work provides useful insights for further understanding the hydrocarbon generation mechanism, as well as quantifying different types of water in organic-rich mudstones.

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泥岩中有机氢和无机氢的定量：利用热解过程中富含有机物和不含有机物泥岩之间差异的新方法

泥岩富含或不含有机物对水的出现有很大影响。比较富含有机物和不含有机物泥岩中不同类型的水有助于进一步了解水在碳氢化合物生成过程中的作用。热重分析法（TGA）和差热分析法（DTA）与质谱法（MS）相结合，可在实时监测的加热过程中确定样品的质量变化、反应和产物。本研究利用 TGA/DTA-MS 方法比较了富含有机质的泥岩（CN1）和不含有机质的泥岩（CW1）的热解特征，以估算富含有机质的泥岩中不同类型的 H2O 和 CO2 的含量。结果表明，CN1 和 CW1 的质量变化可分为 0°C-200°C、200°C-650°C 和 650°C-900°C三个热重（TG）阶段，而通过 MS 获得的 H2O 和 CO2 的峰值温度在 CN1 和 CW1 中是不同的。CN1 和 CW1 在矿物成分和有机物方面的差异表明，CW1 中 H2O 和 CO2 的 MS 峰值主要受粘土和碳酸盐矿物的影响，而 CN1 中的 H2O 和 CO2 峰值也受有机物的影响。此外，利用 CO2 和 H2O 的 MS 峰面积、TGA 中的质量损失以及无机泥岩的矿物组成，可以建立富有机泥岩中有机和无机来源的 CO2 和 H2O 含量的量化方程。这项工作为进一步了解碳氢化合物的生成机制以及量化富含有机质泥岩中不同类型的水提供了有益的启示。

本文章由计算机程序翻译，如有差异，请以英文原文为准。

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来源期刊

Frontiers in Earth Science Earth and Planetary Sciences-General Earth and Planetary Sciences

CiteScore

3.50

自引率

10.30%

发文量

2076

审稿时长

12 weeks

期刊介绍： Frontiers in Earth Science is an open-access journal that aims to bring together and publish on a single platform the best research dedicated to our planet. This platform hosts the rapidly growing and continuously expanding domains in Earth Science, involving the lithosphere (including the geosciences spectrum), the hydrosphere (including marine geosciences and hydrology, complementing the existing Frontiers journal on Marine Science) and the atmosphere (including meteorology and climatology). As such, Frontiers in Earth Science focuses on the countless processes operating within and among the major spheres constituting our planet. In turn, the understanding of these processes provides the theoretical background to better use the available resources and to face the major environmental challenges (including earthquakes, tsunamis, eruptions, floods, landslides, climate changes, extreme meteorological events): this is where interdependent processes meet, requiring a holistic view to better live on and with our planet. The journal welcomes outstanding contributions in any domain of Earth Science. The open-access model developed by Frontiers offers a fast, efficient, timely and dynamic alternative to traditional publication formats. The journal has 20 specialty sections at the first tier, each acting as an independent journal with a full editorial board. The traditional peer-review process is adapted to guarantee fairness and efficiency using a thorough paperless process, with real-time author-reviewer-editor interactions, collaborative reviewer mandates to maximize quality, and reviewer disclosure after article acceptance. While maintaining a rigorous peer-review, this system allows for a process whereby accepted articles are published online on average 90 days after submission. General Commentary articles as well as Book Reviews in Frontiers in Earth Science are only accepted upon invitation.