1. State Key Laboratory of Deep Coal Mining & Environment Protection,Huainan Mining Industry(Group) Co. ,Ltd. ,Huainan　 232001,China; 2. School of Earth and Environment,Anhui University of Science & Technology,Huainan　 232001,China; 3. Exploration Research Institute of Anhui Coal Geology Bureau, Hefei　 230088,China

潘集外围深部煤层气甲烷碳氢同位素分布及其成因对该区煤层气藏的形成和分布规律、煤层气资源评价均具有重要意义。采集了潘集外围深部主要煤层共25件煤样,通过解吸实验获得解吸气样进行了组分、甲烷稳定碳氢同位素测试,分析了深部煤层气组分及稳定同位素分布特征,探讨了煤层气稳定碳氢同位素随埋深的变化特点,结合煤层气形成与演化过程、煤的变质程度分析了煤层气稳定同位素的地质影响,通过Whiticar成因图版揭示了深部煤层气成因,结合相关经验模型估算了煤层气不同成因来源气所占比例。研究结果表明:深部煤样解吸煤层气中CH4含量介于16.2%96.68%,平均为71.60%,重烃含量介于0.35%32.13%,平均为9.86%,N2含量介于0.13%74.72%,平均为21.20%,CO2含量介于1.62%27.26%,平均为7.30%。自浅部至深部煤层甲烷碳同位素变化于-45.46‰-31.17‰,平均为-40.92‰,甲烷氢同位素变化于-199.99‰-133.87‰,平均为-178.04‰,稳定碳氢同位素具有随深度增加偏重的特点。构造热演化史表明研究区煤层气以热成因气为主,兼有生物气可能,研究区煤层Ro,max介于0.702 2%0.998 3%,主要为气-肥煤,生成的煤层气为湿气,油型气的输入使得δ13C1偏重。Whiticar成因图版分析表明研究区煤层气为以热成因为主,经历了后生改造作用的混合气。估算结果表明13-1煤、11-2煤、8煤、7煤、6煤、5煤、4煤、3煤、1煤生成的煤层气中热成因气比例超过80%,生物气主要由CO2还原作用所形成。

The distribution and the origins of carbon and hydrogen isotopes of methane in coalbed methane ( CBM) from deep-seated coal seams around Panji mining area is significant in revealing the formation and the distribution of CBM reservoir,and the source evaluation of CBM. For these reasons,25 coal samples were mainly sampled from the deep-seated coal seams around Panji mining area,the desorbed CBM in Lab were conducted to test CBM component,carbon and hydrogen isotopes of methane. The distribution characteristics of CBM component,stable isotope of methane were analyzed,the variation characteristics between stable isotope of methane and the burial depth of coal seam were discussed. The geological effect of the formation and the evolution of CBM,the metamorphic degree of coal were ana- lyzed,the origins of CBM were revealed by Whiticar chart,the ratios of CBM with different origins were estimated based on the associated empirical model. The results show that the content of CH4 in CBM from the deep-seated coal seams is between 16. 2% -96. 68% with an average of 71. 60% ,the content of heave hydrocarbon in CBM is between 0. 35% -32. 13% with an average of 9. 86% ,the content of N2 is between 0. 13% - 74. 72% with an average of 21． 20% ,and the content of CO2 is between 1. 62% -27. 26% with an average of 7. 30% . Carbon isotope of methane varies between -45. 46‰--31. 17‰ in CBM from the shallow coal seam to the deep coal seam,with an average of -40． 92‰. Hydrogen isotope of methane varies between -199. 99‰--133. 87‰ with an average of -178. 04‰. CBM are characterized by rich heavy carbon and hydrogen isotopes. Tectonic-thermal history of Panji mining area shows that CBM is the thermogenic gas accompanied by the biogas. The average Ro,max of coal seams in the studied area is be- tween 0. 702 2% -0. 998 3% ,the types of coal in the studied area are gas fat coal,the generated CBM is mainly wet gas,the input of oil type gas causes the rich of δ13 C1. The analytical Whiticar chart suggests CBM in the studied area is the thermogenic gas reconstructed by secondary role. The estimated results show that the ratio of the thermogenic gas in the generated CBM from coal Nos. 13-1,11-2,8,7,6,5,4,3 and 1 is above 80% ,and the biogas is generated by the reduction of CO2 .

LIU Huihu,LAN Tianhe,HU Baolin,et al. Geochemical characteristics and its origins of CBM in deep-seated coal seam around Panji min- ing area of Huainan[J]. Journal of China Coal Society,2018,43(2):498-506.