摘要
超临界二氧化碳(ScCO_2)–H_2O–煤地球化学反应可造成煤物理结构和化学结构的改变,对煤层注CO_2增采甲烷的有效性尤为关键。为了探讨ScCO_2-H_2O-煤反应对不同变质程度煤化学结构的影响,选择3个不同煤化程度煤样,在自主研制的ScCO_2-H_2O-煤地球化学反应模拟实验装置中模拟1 000 m埋深条件下煤样与ScCO_2和去离子水反应240 h,并对反应前后的煤样分别进行了X射线衍射和拉曼光谱实验,对比分析了反应前后煤样晶体结构和碳有序度的变化特征。测试结果表明:ScCO_2-H_2O反应破坏了煤的晶体完整性和碳有序度,改变了煤的大分子结构,且对低阶煤和中–高阶煤具有不同的影响,反应提高了低阶煤的平行定向程度,使其结构更加紧凑,减小了面网间距,而使中–高阶煤中无序单元增加,面网间距增大。该研究结果为CO_2-ECBM项目实施中ScCO_2-H_2O作用对煤储层吸附解吸特征和孔渗特征影响的研究奠定了微观尺度基础。
ScCO2-H2O-coal geochemical reaction can exert a great influence on the physical and chemical structure of coal,playing a critical role in the CO2 injection and enhancing CH4 recovery.To investigate the effects of ScCO2-H2O on chemical structure in coal,three coal samples of different metamorphic grades were exposed to supercritical CO2 and deionized water under 1 000 m depth temperature and pressure conditions for 240 h using a high pressure reactor(ScCO2/H2O simulation system and coal/rock geochemical reaction device).X-ray diffraction and Raman spectroscopy were used to provide change characteristics of crystal structure and carbon order degree of coal before and after the ScCO2-H2O treatment.The results show that the ScCO2-H2O reaction destroys the crystal structural integrity and carbon order degree and changes the macromolecular structure of coal,the effect mainly depends on the coal rank,i.e.,for low rank coals,the degree of parallel orientation increases and makes its structure more compact,the lamellae spacing decreases;while for medium-high rank coals,the disordered structure and lamellae spacing of the coal microcrystalline structure increases.This study result has laid a micro-scale foundation for the adsorption/desorption,pore and permeability characterization of coal reservoir before and after ScCO2-H2O action in the implementation of the CO2-ECBM project.
作者
王恬
桑树勋
刘世奇
杜艺
WANG Tian;SANG Shuxun;LIU Shiqi;DU Yi(Key Laboratory of Coalbed Methane Resources and Reservoir Formation Process,Ministry of Education,School of Mineral Resource and Geoscience,China University of Mining and Technology,Xuzhou 221008,China;East China University of Technology,Nanchang 330000,China;Key Laboratory of Coal-based CO2 Capture and Geological Storage,Jiangsu Province,Low Carbon Energy Institute,China University of Mining and Technology,Xuzhou 221116,China)
出处
《煤田地质与勘探》
CAS
CSCD
北大核心
2018年第5期60-65,共6页
Coal Geology & Exploration
基金
国家自然科学基金项目(41330638)~~
