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在新集、李雅庄和恩洪地区发现次生生物成因煤层气,是中国煤层气的一种新的成因与资源类型．其基本特征为：组分以甲烷为主,C_1/C_(1-5)＞0.99,属于干气；δ~(13)C_1值为-61.7‰～-47.9‰,绝大部分＜-55‰,比该区煤岩所处热演化阶段(R_o值为0.87%～1.43%)所产热成因甲烷的δ~(13)C估算值低得多,显示甲烷具次生生物成因特征；δD_((CH)_4)值为-244‰～-196‰；δ~(13)C_2值为-26.7‰～-15.9‰,δ~(13)C_3值为-10.8‰～-25.3‰,重烃属热成因；CO_2含量极低,δ~(13)C值变化很大,反映出次生变化的特征；δ~(15)N_2值主要在-1‰～+1‰之间,指示N_2主要源于大气,而N_2与CH_4含量之间具良好的负相关线性关系,反映出含菌地表水渗入煤层的活动．综合示踪指标研究表明,研究区煤层气为以次生生物气为主,含有部分残留热成因气的混合气．煤层抬升和断裂发育为次生生物气的形成提供了良好条件．
The discovery of secondary biogenic coalbed methane in the Xinji, Liyazhuang and Enhong regions is a new cause and resource type of CBM in China. The main features are: the main components of methane, C_1 / C_ (1-5)> 0.99, are dry gas; δ ~ (13) C_1 value of -61.7 ‰ ~ -47.9 ‰, the vast majority of <-55 ‰ , Which is much lower than the δ ~ (13) C estimated value of methane from the thermal evolution stage (R_o = 0.87% ~ 1.43%) in the thermal evolution stage of coal and rock in this area, indicating that methane has the characteristics of secondary genesis. ΔD_ (CH_4) value of -244 ‰ ~ -196 ‰; δ ~ (13) C_2 value of -26.7 ‰ ~ -15.9 ‰, δ ~ (13) C_3 value of -10.8 ‰ ~ -25.3 ‰, (15) N_2 value is mainly between -1 ‰ ~ + 1 ‰, which indicates the main source of N_2 In the atmosphere, there is a good negative correlation between N_2 and CH_4, indicating the infiltration of bacteria-containing surface water into the coal seam. Comprehensive tracing index research shows that the CBM in the study area is mainly composed of secondary biogas, which contains some residual pyrogen gas. Seam uplift and fracture development provide a good condition for the formation of secondary biogas.