鄂尔多斯盆地富县地区延长组长7烃源岩特征及评价

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

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(S 1+S 2)平均为13.1 mg/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C 31藿烷22S/(22R+22S)、20RC 29αββ/(αββ+ααα)和αααC 2920S/(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。

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 spec‐trometry 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(S 1+S 2)was 13.1 mg/g.(2)The types of organic matter were mainly type I andⅡ1,and the source of the source rock was mainly composed of lower aquatic organisms and contained some higher plants.The water body was a reduc‐ing environment during sedimentation.(3)The vitrinite reflectance averaged 0.76%.Among the biomarker com‐pounds,C 31 hopane 22S/(22R+22S),20RC 29αββ/(αββ+ααα)andαααC 2920S/(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 produc‐tion.(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 re‐sults play an important guiding role for fine exploration in Fuxian area of the Ordos Basin.