CO_(2)−水−煤地球化学作用对淮南煤田CO_(2)驱煤层气增产效果的影响  

Impact of CO_(2)-water-coal on enhanced coalbed methane recovery by CO_(2)injection in Huainan coalfield

作　　者：张贺龙 刘世奇[2,3] 田钰琛 王文楷 桑树勋[1,2,3,4] 郑司建 李兵[5,6] 陈永春 ZHANG Helong;LIU Shiqi;TIAN Yuchen;WANG Wenkai;SANG Shuxun;ZHENG Sijian;LI Bing;CHEN Yongchun(School of Resources and Earth Sciences,China University of Mining and Technology,Xuzhou 221116,China;Key Laboratory of Coal-based Greenhouse Gas Emission Reduction and Resource Utilization,China University of Mining and Technology,Xuzhou 221008,China;Carbon Neutrality Research Institute,China University of Mining and Technology,Xuzhou 221116,China;Key Laboratory of Coalbed Methane Resources and Reservoir Formation Process,Ministry of Education,China University of Mining and Technology,Xuzhou 221008,China;Huainan Mining Industry(Group)Co.,Ltd.,Huainan 232001,China;Ping'an Mining Engineering Technology Research Institute Co.,Ltd.,Anhui Coal Mine Green and Low Carbon Development Engineering Research Center,Huainan 232033,China)

机构地区：[1]中国矿业大学资源与地球科学学院,江苏徐州221116 [2]中国矿业大学江苏省煤基温室气体减排与资源化利用重点实验室,江苏徐州221008 [3]中国矿业大学碳中和研究院,江苏徐州221116 [4]中国矿业大学煤层气资源与成藏过程教育部重点实验室,江苏徐州221008 [5]淮南矿业(集团)有限责任公司,安徽淮南232001 [6]平安煤炭开采工程技术研究院有限责任公司安徽省煤矿绿色低碳发展工程研究中心,安徽淮南232033

出　　处：《煤炭科学技术》2025年第3期274-290,共17页Coal Science and Technology

基　　金：国家自然科学基金资助项目(42141012,42302194)。

摘　　要：CO_(2)驱煤层气封存(CO_(2)-ECBM)是重要的CO_(2)地质利用与地质封存方式,有望破解以淮南煤田为代表的松软、低渗、难抽采煤层煤层气开发效果差、产量衰减快等难题,提高煤层气产量和采收率。CO_(2)注入煤层与煤中无机矿物的地球化学作用可导致煤层孔裂隙结构和渗透性的变化,对煤层CO_(2)封存能力和煤层气增产效果具有显著影响。为此,考虑有效应力、温度及地球化学效应影响下的CO_(2)与CH_(4)竞争吸附、扩散与渗流作用、CO_(2)−水−煤地球化学作用及其影响的煤层孔隙率与渗透率动态演化特征,建立了CO_(2)注入煤储层渗流场−应力场−温度场−化学场全耦合数学模型,开展了淮南煤田CO_(2)-ECBM工程数值模拟研究,分析了地球化学作用条件下,CO_(2)注入煤层增产CH_(4)效果,以及CO_(2)注入压力、初始渗透率和含水饱和度等对CH_(4)增产、CO_(2)封存的影响。结果表明:数学模型与试验结果吻合度较高,CH_(4)、CO_(2)混合气体体积分数及产出速率平均误差为1%~10%;相较于未考虑地球化学作用的情况,模拟周期内CH_(4)累计产量降低11%,CO_(2)累计封存量提升19.8%,表明忽略CO_(2)−水−煤地球化学作用会高估CH_(4)增产效果和低估CO_(2)封存量;注入压力和煤储层初始渗透率越大,CH_(4)增产效果越显著,CO_(2)封存量越大;而高含水饱和度对CH_(4)增产和CO_(2)封存产生不利影响,指示了CO_(2)驱煤层气封存应结合储层性质,优选目标层位,并通过合理设计注入工艺最大化CH_(4)增产和CO_(2)封存效果;CO_(2)−水−煤地球化学作用能够缓解CO_(2)注入导致的储层压力升高,降低裂隙中自由态CO_(2)含量,进而抑制应力−应变效应造成的煤储层渗透率下降,促进渗透率的回升,渗透率回升幅度达2.4%~3.3%,而渗透率回升进一步促进了储层压力传导和CO_(2)吸附、CH_(4)解吸与扩散,从而提升CH_(4)增产和CO_(2)封存效果。CO_(2)-enhanced coalbed methane recovery(CO_(2)-ECBM)is a key method for CO_(2)geological utilization and sequestration.It holds promise for addressing challenges such as soft,low-permeability coal seams with difficult gas extraction,poor development performance,rapid production decline,and low recovery rates,as exemplified by the Huainan coalfield.The geochemical interactions of CO_(2)injection into coal seams and inorganic minerals in coal can alter the pore-fracture structure and permeability of the coal,significantly influencing CO_(2)sequestration capacity and methane production enhancement.Therefore,considering the effects of effective stress,temperature,and geochemical interactions—including competitive adsorption,diffusion,seepage of CO_(2)and CH_(4),and CO_(2)-water-coal geochemical interactions,as well as their impact on the dynamic evolution of coal seam porosity and permeability—a fully coupled Thermo-Hydro-Mechanical-Chemical mathematical model was developed for the seepage-stress-temperature-chemical interactions in CO_(2)-injected coal reservoirs.Numerical simulation studies on CO_(2)-ECBM were conducted for the Huainan coalfield to analyze the effect of geochemical interactions on CH_(4)production enhancement during CO_(2)injection,as well as the influence of injection pressure,initial permeability,and water saturation on CH_(4)production and CO_(2)sequestration.The results showed a high degree of consistency between the mathematical model and experimental outcomes,with the average error range for CH_(4)and CO_(2)mixture volumetric fractions and production rates falling within 1%−10%.Compared to scenarios ignoring CO_(2)-water-coal geochemical interactions,the cumulative CH_(4)production decreased by 11%,while cumulative CO_(2)storage increased by 19.8%,indicating that neglecting geochemical interactions could lead to an overestimation of CH_(4)production and underestimation of CO_(2)storage capacity.Higher injection pressures and initial permeability of coal reservoirs resulted in more sign

关 键 词：煤层气增产 地球化学作用 注入压力 渗透率 含水饱和度 CO_(2)地质封存 

分 类 号：TD824[矿业工程—煤矿开采]