Wei Qiang, Hu Baolin, Fang Huihuang, Chen Song, Feng Songbao, Wu Cancan, Zheng Chunshan
School of Resources and Civil Engineering, Suzhou University, Suzhou 234000, P. R. China.
Institute of Energy, Hefei Comprehensive National Science Center, Hefei 230031, P. R. China.
ACS Omega. 2022 May 19;7(21):17929-17940. doi: 10.1021/acsomega.2c01227. eCollection 2022 May 31.
To investigate the geochemical characteristic, genetic types, and accumulation model of coalbed methane (CBM), 16 samples from a burial depth of 621-1494 m were collected in the Panxie Coal Mining Area of Huainan Coalfield. The results indicate that the samples are dominated by methane, and the concentrations are distributed in the range of 73.11-95.42%. The dryness coefficient is 0.77-1.00 (average, 0.93), and the ratio of methane to the sum of ethane and propane (C/(C + C)) is 3.18-242.64 (average, 36.15). The δC values are distributed in the range of -65.44 to -32.38‰ (average, -45.22‰), the δD values are in the range of -226.84 to -156.82‰ (average, -182.93‰), and the δC values are in the range of -19.7 to -10.1‰ (average, -15.51‰). CBM samples in the study area are dominated by thermogenic gases, followed by secondary biogenic gases with CO reduction. For the percentages of different genetic gases, the distribution range of thermogenic gas is 70.11-97.86%, whereas that of biogenic gas is 58.65-77.86% for five samples from Zhangji, Panyi, Pansan, and Panbei Coalmines. Moreover, desorption-diffusion fractionation and the effect of groundwater dissolution occurred in the Panxie Coal Mining Area, and higher δC values mostly existed in the deeper coal seams. Furthermore, the biogenic gases are more likely to be secondary biogenic gases generated by CO reduction on the basis of data comparison, which is related to the flowing water underground. Accumulation models of different genetic types of CBM are correlated with the burial depth of coal seams, location, and type of faults and aquifers.
为研究煤层气（CBM）的地球化学特征、成因类型及聚集模式，在淮南煤田潘谢矿区采集了16个埋深621 - 1494 m的样品。结果表明，样品以甲烷为主，浓度分布在73.11% - 95.42%范围内。干燥系数为0.77 - 1.00（平均0.93），甲烷与乙烷和丙烷之和的比值（C/(C₂ + C₃)）为3.18 - 242.64（平均36.15）。δ¹³C值分布在-65.44‰至-32.38‰范围内（平均-45.22‰），δD值在-226.84‰至-156.82‰范围内（平均-182.93‰），δ¹⁸O值在-19.7‰至-10.1‰范围内（平均-15.51‰）。研究区煤层气样品以热成因气为主，其次为次生生物成因气并伴有CO还原作用。对于不同成因气体的占比，张集、潘一、潘三及潘北煤矿的5个样品中，热成因气的分布范围为70.11% - 97.86%，而生物成因气的分布范围为58.65% - 77.86%。此外，潘谢矿区发生了解吸 - 扩散分馏和地下水溶解作用，较高的δ¹³C值大多存在于较深的煤层中。此外，基于数据对比，生物成因气更可能是由地下流水导致CO还原生成的次生生物成因气，不同成因类型煤层气的聚集模式与煤层埋深、断层位置及含水层类型相关。
