Previous natural gas explorations in Ordos Basin were conducted in areas with thick coal deposited. Recently, natural gas flow were discovered in southern basin where very thin coal seams were developed, implying the contribution from other source rocks, e.g. the coal measure mudstones. In order to thoroughly assess the quality and gas potential of coal measure mudstones, 58 mudstones from borehole were analyzed by Rock-Eval method and gold-tube pyrolysis was carried out on immature carbonaceous and dark mudstones with detailed geochemical characteristics of hydrocarbon products detected.

The results indicated the mudstones were dominated by type III kerogen and assisted by type II kerogen and were fair to good source rocks. Pyrolysis data demonstrated the peak yield of C_1-5 for carbonaceous mudstone was very close to that of coal, whereas the maximum C_1-5 yield for dark mudstone accounted for 62.5% of that of carbonaceous mudstone, indicating the good gas potential of carbonaceous mudstone. The generated gaseous hydrocarbons were predominately derived from primary kerogen cracking.

The computed activation energy of C_1-5 for carbonaceous mudstone showed a more discrete distribution compared to dark mudstone. The modeled methane conversion for dark mudstone was higher than that of carbonaceous mudstone since entering main gas generation stage, which was consistent with the concentrated and lower activation energies for dark mudstone. Furthermore, the modeled gas in southern basin was much higher than that in central basin, due to the more severe thermal alteration that coal measures in southern basin had experienced.

On the basis of the integrated analysis of methane generation and adsorption, the areas with thick carbonaceous mudstone deposited had fair exploration prospects and further gas explorations should pay more attention on.

鄂尔多斯盆地以前的天然气勘探是在沉积有厚煤的地区进行的。最近，在南部盆地发现了天然气流，那里的煤层很薄，这暗示了其他烃源岩（如煤质泥岩）的贡献。为了全面评价煤系泥岩的质量和气田潜力，采用Rock-Eval方法分析了58个井眼的泥岩，并对未成熟的碳质和深色泥岩进行了金管热解，并详细检测了烃类产品的地球化学特征。

结果表明，该泥岩以Ⅲ型干酪根为主，Ⅱ型干酪根为辅，对优质烃源岩是公平的。热解数据表明，碳质泥岩的C _1-5峰值产率与煤非常接近，而深色泥岩的最大C _1-5产率占碳质泥岩的62.5％，表明碳质泥岩具有良好的气藏潜力。泥岩。产生的气态烃主要来自初级干酪根裂解。

与深色泥岩相比，碳泥岩的C _1-5计算活化能显示出更离散的分布。自进入主气生成阶段以来，模拟的深色泥岩甲烷转化率高于含碳泥岩甲烷转化率，这与深色泥岩的集中和较低的活化能相一致。此外，由于南部盆地煤系经历了更严重的热变化，南部盆地的模拟天然气远高于中部盆地。

在甲烷生成与吸附综合分析的基础上，沉积有较厚碳质泥岩的地区具有广阔的勘探前景，应进一步重视天然气勘探。