煤中超临界CO2解吸滞后机理及其对地质封存启示

扫码查看

原文链接

万方数据

中文摘要：将CO2 注入不可采煤层地质封存既是降低温室气体效应最理想选择之一，也是煤炭工业降低CO2 排放、实现低碳化可持续发展的必由之路，然而，煤层CO2 地质封存悬而未决的关键问题是:"注入煤层中的CO2 到底能否长期停留而安全封存?"。鉴于此，在弄清煤体CO2 解吸滞后规律的基础上，揭示超临界CO2 解吸滞后机理，建立煤层CO2 地质封存量化模型，探讨利用解吸滞后实现煤层CO2 长期安全封存。研究表明:煤中超临界态CO2 解吸滞后程度大于亚临界态CO2，在超临界阶段，吸附与解吸等温线形成近似"平行线"的稳定滞后特征;解吸滞后的本质原因是煤中微纳米级亲水性孔隙形成弯液面、产生强大毛细压力、渗吸液态水、截断并固定超临界CO2 流体、最终形成了CO2 残余封存，例如，煤中直径40～10 nm圆柱形无机孔隙可产生7。30～29。12 MPa毛细压力，足以封堵超临界态CO2;以九里山煤样解吸等温线数据为例，采用基于煤层CO2 解吸滞后的地质封存量化模型，评估出 900～1 500 m深部二1 煤层封存总量稳定在 35～37 m3/t，其中，吸附封存约占 80%，残余封存约占 15%，而结构封存仅占 5%;解吸滞后启示应尽可能采取措施提高煤层残余封存CO2 比例，原因是毛细堵塞的残余封存CO2 较围岩密封的游离和吸附CO2 更安全且没有泄露风险，煤层灰分、水分、孔隙尺寸和形貌等物性参数是影响残余封存效率的主要因素。

外文标题：Hysteresis mechanism of supercritical CO2 desorption in coal and its implication for carbon geo-sequestration

外文摘要：Sequestration of CO2 in the unmineable coal seams is not only one of the most ideal options for reducing green-house gas effects,but also the only way for the coal industry to reduce CO2 emissions and achieve low carbonization sus-tainable development.However,the key unresolved issues regarding the CO2 geo-sequestration in coal seams is:"how long does CO2 injected into a coal seam remain in the seam?".In this regard,on the basis of clarifying the hysteresis law of CO2 desorption in coals,this paper reveals the mechanism of supercritical CO2 desorption hysteresis,establishes a quantitative model for the geological storage of CO2,and explores the use of desorption hysteresis to achieve a long-term safe storage of CO2 in coal seams.The study results shows that the degree of desorption hysteresis of supercritical CO2 in coal is greater than that of subcritical CO2,and a stable hysteresis characteristic similar to a"parallel line"in the supercrit-ical phase is formed between the adsorption and desorption isotherm.The fundamental reason for the desorption hyster-esis is that the micro and nano sized pores in coal form curved surfaces due to their hydrophilicity,which generate strong capillary pressure following the Laplace's equation,absorb liquid water,truncate and fix the supercritical CO2 fluid,and ultimately form CO2 residual trapping.For example,the cylindrical inorganic pores with a diameter of 40-10 nm in coal can generate a capillary pressure of 7.30-29.12 MPa,which is sufficient to block supercritical CO2.Taking the desorption isotherm of Jiulishan coal as an example,using the quantitative model for the geological storage of CO2 established in this study,it has been estimated that the total trapping capacity of the No.21 coal seam at depths of 900-1 500 m is stable at 35-37 m3/t.Among them,the adsorption trapping capacity accounts for about 80%,residual trapping capacity accounts for about 15%,and structural trapping capacity only accounts for 5%.Desorption hysteresis suggests that some measures should be taken to increase the proportion of CO2 residual trapping in coal seams as much as possible,the reason is that the residual CO2 sealed by capillary blockage is safer and has no risk of leakage compared to the free and adsorbed CO2 sealed by surrounding rock.The physical parameters such as ash content,moisture content,pore size,and morphology of coal seams are the main factors affecting the residual trapping efficiency.

外文关键词：

CO2 geo-sequestrationsupercritical CO2desorption hysteresisresidual trappingcapillary pressureQuantitative model for carbon geo-sequestration

作者：

刘操、闫江伟、赵春辉、钟福平、贾天让、刘小磊、张航

展开 >

作者单位：

河南理工大学安全科学与工程学院,河南焦作 454003

河南理工大学河南省瓦斯地质与瓦斯治理重点实验室-省部共建国家重点实验室培育基地,河南焦作 454000

全国煤炭行业瓦斯地质与瓦斯防治工程研究中心,河南焦作 454003

中原经济区煤层(页岩)气河南省协同创新中心,河南焦作 454000

煤炭安全生产与清洁高效利用省部共建协同创新中心,河南焦作 454000

展开 >

关键词：

CO2地质封存超临界CO2 解吸滞后残余封存毛细压力地质封存量化模型

基金：

河南省高校基本科研业务费专项资金资助项目河南省科技攻关资助项目河南省高校重点科研资助项目

项目编号：

NSFRF24030122210232015422A610009

出版年：

2024

DOI：

10.13225/j.cnki.jccs.2023.0738

煤炭学报

中国煤炭学会

煤炭学报

CSTPCD北大核心

影响因子：3.013

ISSN：0253-9993

年,卷(期)：2024.49(7)

参考文献量19