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文章主要是对柴达木盆地中东部地区上第三系狮子沟组（N₂3）生物气及其源岩地球化学特征、形成条件进行综合分析，并结合生物气成因模拟实验结果，利用盆地模拟系统，确定该层段生物气资源潜力，明确勘探前景。研究表明，狮子沟组气样组分中甲烷含量为98.01％，乙烷和丙烷含量极低，δ13C₁值为-67.3‰，δ13C_CO2值为-13.7‰，为生物气的特征； 而N₂3层段稳定快速的沉积／沉降、沉积时寒冷的气候条件和高盐度的水体环境为生物气的形成提供了有利条件，其有机质类型以Ⅱ₂（腐泥腐殖型）和Ⅲ（腐殖型）型为主，有机碳含量相对较高，平均为0.36％；盆地模拟结果表明本区N₂3层段生物气生气强度一般为（1500～9 000）×106m3/km2，初步估算生物气地质资源量为4267×108m3。2001年在本区的伊克雅乌汝构造钻探伊深1井，于N₂3层段首次获得生物气工业气流，并上交预测储量295×108m3，展示了良好的勘探前景。

Geochemical Characteristics of Biogas in N23 in Middle-East Chaidamu Basin

On the basis of analyzing comprehensively the geochemical characteristics and formation conditions of the biogas in Shizigiu formation of Pliocene（N23）in middle east Chaidamu Basin and its source rocks，and in combination with the biogas origin simulation test results，the resource potential and exploration prospects for the biogas in such an interval are determined by use of the basin simulation system in the paperThrough researching it is indicated that the methane content in the gas sample collected from N23 is 98.01％；the ethane and propane content is very slight；and the δ13C1 and δ13CCO2 are-67.3‰ and-13.7‰ respectively；so it shows a biogas featureIn the case of N23，a stable and fast sedimentation/subsidence，cold climatic conditions and high salinity water environment provided some favorable conditions for the biogas gas’being generated in it；the main types of organic matters in it are TypeⅡ2（sapropelic humic type）and Type Ⅲ（humic type）；and its organic carbon content is relatively high，being 0.36％（average value）.Basin simulation results indicate that in N23，biogas generation intensities are（1500 ~ 9000）×106m3/km2 in general and the biogas resources estimated primarily are 426.7×109m3, therefore the biogas resource potential is relatively abundant in this regionIn 2001，a commercial gas flow was found out in N23 for the first time in well Yishen―1 drilled in Yikeyawuru structure in this region；and forecast reserves of 29.5×109m3 were reported to the leadership；which shows good exploration prospects.