济阳坳陷古近系沙河街组页岩有机质热演化特征

钻探显示渤海湾盆地济阳坳陷古近系沙河街地层具有良好的页岩油资源潜力，成熟页岩厚度超过1 000 m，其有机质热演化特征备受关注。通过对研究区5口页岩油钻井岩石热解地化参数详细统计和对烃源岩原始有机碳、可转换碳、页岩含油量以及生烃潜力等页岩有机质特征的分析，探讨了页岩镜质体反射率动力学应用范畴。沙河街组（沙三段下亚段和沙四段上亚段）页岩最大热解温度（Tmax）为423～450 ℃，有机质成熟度（Ro）为0.45%～0.94%，平均为0.73%，Ⅱ型烃源岩原始有机碳（TOCo）含量为0.92%～5.67%，平均为4.23%，可转换碳（Cc）比例为51%～63%，平均为59%，页岩含油量(S1)为（10～75）×104 t/km2，平均为39.67×104 t/km2，生烃潜力(S2)为（20～465）×104 t/km2，平均为293×104 t/km2，热解产量指数(PI)为0.03～0.47。综合研究认为，济阳坳陷沙河街组优质烃源岩主要集中在东营凹陷和沾化凹陷，有机质成熟度对页岩油的生成和聚集至关重要，当Ro为0.70%～0.74%时，油气开始大量生成，并且开始排烃。

Characteristics of shale organic matter thermal evolution in Paleogene Shahejie Formation in Jiyang depression

Paleogene Shahejie Formation is investigated for its excellent shale oil potential in Jiyang depression, Bohai Bay Basin. The thickness of Shahejie Formation shale within the oil window reaches more than 1000 m and the characteristics of shale organic matter thermal evolution has attracted widespread interest. Based on the detailed statistics of the pyrolysis geochemical parameters for five exploration wells for shale oil， the analyses of original total organic carbon (TOCo) of a source rock, the convertible carbon (Cc), the oil in place from S1 and generation potential from S2 etc., the characteristics of the shale organic matter thermal evolution of Shahejie Formation has been studied, and the vitrinite reflectance kinetics of shale has also been discussed in this paper. The results suggest that Shahejie Formation shale（lower part of the 3rd and upper part of the 4th Member of Shahejie）is of particular exploration interest, which yields the maximum pyrolysis temperature (Tmax) values ranging from 423 ℃ to 450 ℃.The thermal maturity (Ro) values range from 0.45% to 0.94% with the average value of 0.73%, implying that it belongs to the mature oil window shale. Original total organic carbon (TOCo) values of a source rock of type II values range from 0.64% to 7.25%, and the average TOCo is 4.60%. Organic carbon converted to hydrocarbons is called convertible carbon (Cc), and its values range from 51% to 63%, with the average Cc value of 59%. The oil content of shale values range from 10×104 t/km2 to 75×104 t/km2, with average value of 39.67×104 t/km2. The hydrocarbon generating potential values range from 20×104 t/km2 to 465×104 t/km2, with average value of 293×104 t/km2. Pyrolysis production index (PI) (or S1/［S1+S2］) values range from 0.03 to 0.47. The comprehensive study reveals that the excellent source rocks of Shahejie Formation are concentrated in Dongying and Zhanhua sags, and the thermal maturity is significant for the generation and accumulation of shale oil. When the Ro values were at about 0.70%0.74% the expulsion of hydrocarbons began.