黏结性对富油煤热解孔隙结构演变及渗流的影响研究  

Impacts of the caking property of tar-rich coals on their pore structure evolution and seepage during pyrolysis

作　　者：畅志兵[1] 王楚楚 旷文昊 唐颖 吴晓丹 刘淑琴[1] CHANG Zhibing;WANG Chuchu;KUANG Wenhao;TANG Ying;WU Xiaodan;LIU Shuqin(School of Chemical and Environmental Engineering,China University of Mining and Technology(Beijing),Beijing 100083,China;CNOOC Gas&Power Group,Research&Development Center,Beijing 100028,China;China National Offshore Oil Corporation,Key Laboratory of Liquefied Natural Gas and Low Carbon Technology,Beijing 100028,China)

机构地区：[1]中国矿业大学(北京)化学与环境工程学院,北京100083 [2]中海石油气电集团技术研发中心,北京100028 [3]中国海洋石油集团有限公司液化天然气及低碳技术重点实验室,北京100028

出　　处：《煤田地质与勘探》2024年第7期54-63,共10页Coal Geology & Exploration

基　　金：中央高校基本科研业务费专项项目(2024ZKPYHH04);中海石油气电集团科技项目(QDKY-2023-YFZX-02)。

摘　　要：【目的】富油煤的原位热解是将煤层在地下加热生产油气的技术,其中煤层的孔隙结构和渗透特性是影响加热介质注入和油气产出的重要因素。黏结性富油煤热解伴随胶质体的形成,使其孔隙结构和渗透特性不同于非黏结性煤。【方法】将黏结性富油煤在300、400、500和600℃下热解,采用饱和流体法和氮吸附法测试半焦的孔隙参数,并采用显微CT表征半焦的孔隙结构;通过构建等效孔隙网络模型,分析煤样孔隙数目、孔隙半径和配位数等参数的变化规律,并模拟高温N2在孔隙网络中的渗流特征。【结果和结论】结果表明:煤样经300℃热解后仅产生少量裂隙,总孔隙率维持在约5%;当热解温度为400~600℃时,总孔隙率逐渐增至约50%,而微观孔隙仅在600℃脱气后更为丰富。当热解温度由300℃升至400℃,胶质体的形成、膨胀使孔隙和喉道的数量显著增大,但平均半径分别维持在约160μm和约88μm;再由400℃升至600℃,挥发分的析出促进了孔隙结构的连通,使孔隙和喉道的数量逐渐减少,且概率分布向等效半径更大的范围偏移,使平均半径分别增至292.81μm和170.60μm,并使孔隙平均配位数由5.82分别增至6.60和6.33,孔隙率和配位数的增大使半焦的平均模拟渗透率由246.75μm2显著增至1377.49μm2。研究结果可为黏结性富油煤原位热解的工艺研发提供参考依据。[Objective]The in-situ pyrolysis of tar-rich coals stands as a technique whereby coal seams are heated underground to produce tar and gas products.During the in-situ pyrolysis,the injection of heating media and the production of tar and gas are affected by the pore structure and permeability of coal seams.Since pyrolysis of caking tar-rich coals is accompanied by the formation of colloids,the pore structure and permeability of caking tar-rich coals differ from those of non-caking tar-rich coals.[Methods]Caking tar-rich coals were pyrolyzed at 300,400,500,and 600℃.During the pyrolysis,the pore parameters of the semi-coke were tested using the saturated fluid method and nitrogen adsorption method,and the pore structure of the semi-coke was characterized using micro-computed tomography(micro-CT).Meanwhile,using equivalent pore network models established in this study,the laws of changes in parameters such as the pore number,pore radius,and coordination number were analyzed,and the seepage characteristics of high-temperature nitrogen in the pore network were simulated.[Results and Conclusions]The results revealed small numbers of fissures in the coal samples after the pyrolysis at 300℃,with a total porosity maintained at about 5%.After pyrolysis at temperatures ranging from 400℃to 600℃,the total porosity gradually increased to about 50%,while micropores became more abundant only after degassing at 600℃.When the pyrolysis temperature rose from 300℃to 400℃,the number of pores and throats increased significantly due to the formation and expansion of colloids,whereas the average pore and pore-throat radii were maintained at about 160μm and 88μm,respectively.As the pyrolysis temperature increased further from 400℃to 600℃,the precipitation of volatile constituents promoted the pore connectivity.Accordingly,pores and throats gradually decreased in number,with equivalent radii trending upward in terms of probability distribution.Specifically,the average pore and pore-throat radii increased to 292.81μm an

关 键 词：富油煤 热解 显微CT 三维表征 孔隙结构 渗透率 

分 类 号：TQ530.2[化学工程—煤化学工程] P618.11[天文地球—矿床学]