鄂尔多斯盆地富县地区延长组长7烃源岩特征及评价

为研究鄂尔多斯盆地富县地区延长组长7烃源岩特征及生烃潜力，开展了岩心分析、测井研究、干酪根镜检、镜质体反射率（R_o）测试、岩石热解分析、气相色谱及色谱-质谱分析。结果表明：（1）富县地区长7烃源岩平均厚度为45 m；总有机碳（TOC）质量分数平均为5.94%；生烃潜量（S₁+S₂）平均为13.1mg/g。（2）有机质类型以Ⅰ和Ⅱ₁型为主，烃源岩母质类型以低等水生生物为主，并含部分高等植物，沉积时水体为还原环境。（3）镜质体反射率平均为0.76%，生物标志化合物中C₃₁藿烷22S（/22R+22S）、20RC₂₉αββ（/αββ+ααα）和αααC₂₉20S（/20S+20R）平均值分别为0.52、0.62和0.49，反映有机质演化进入生油高峰阶段。（4）平面上，富县地区中部和西北部长7烃源岩厚度大、生烃能力更强，为下一步勘探的有利区带。该研究成果对鄂尔多斯盆地富县地区的精细勘探具有重要指导作用。

Characteristics and evaluation of Chang 7 source rock of Yanchang Formation in Fuxian area,Ordos Basin

In order to study the characteristics and hydrocarbon generation potential of Chang 7 source rock of Yanchang Formation in Fuxian area of Ordos Basin,core analysis,well logging research, kerogen microscopy, vitrinite reflectance(R_o) test,rock pyrolysis analysis, gas phase chromatography and chromatography-mass spectrometry were carried out. The results show that:(1) The average thickness of Chang 7 source rock in Fuxian area was 45 m,the TOC mass fraction averaged 5.94%,and the average hydrocarbon generation potential(S₁+S₂) was 13.1 mg/g.(2)The types of organic matter were mainly type I and Ⅱ₁,and the source of the source rock was mainly composed of lower aquatic organisms and contained some higher plants. The water body was a reducing environment during sedimentation.(3)The vitrinite reflectance averaged 0.76%. Among the biomarker compounds, C₃₁ hopane 22S(/22R+22S),20RC₂₉αββ(/αββ+ααα)and αααC₂₉20S(/20S+20R), the average values were 0.52,0.62,0.49,respectively,reflecting the evolution of organic matter into the peak stage of oil production.(4)On the plane, Chang 7 source rocks in the central and northwestern Fuxian area have large thicknesses and stronger hydrocarbon generation capacity, which is a favorable zone for further exploration. The research results play an important guiding role for fine exploration in Fuxian area of the Ordos Basin.