鄂尔多斯盆地庆阳-镇原地区长8原油地球化学特征研究

Geochemical Characteristics of Chang-8 Crude Oil in Qingyang-Zhenyuan Area of Ordos Basin

文章以庆阳-镇原地区中生界三叠系延长组长8油藏原油和长7暗色泥岩为研究对象,借助岩石热解、烃源岩有机质镜鉴、色谱-质谱等分析测试手段,开展长8油藏原油地球化学特征、长7烃源岩综合评价和油源对比研究.结果表明:庆阳-镇原地区长8原油物性较好,低碳数正构烷烃在原油中占优势,其原油母质构成既有陆生植物,又有低等水生生物,而且低等水生生物对于原油的贡献相对较大.原油中Ts/Tm值处于适中水平,已达到成熟原油的标准.对庆阳-镇原地区的油源进行对比分析,表明长8原油主要来自于长7烃源岩.

Taking Chang-8 oil and Chang-7 dark mudstone of Yanchang Formation of Triassic in Qingyang-Zhenyuan area as the research object,this paper conducted geochemical characteristics of Chang-8 oil,comprehensive evaluation of Chang-7 source rock and oil source correlation study by means of rock pyrolysis,organic matter microscopy of source rock,chromatography-mass spectrometry and other analytical tests.The results show that the Chang-8 oil in Qingyang-Zhenyuan area has good physical properties,low carbon number n-alkanes are dominant in crude oil,and the parent material of crude oil consists of both terrestrial plants and aquatic organisms,and the contribution of aquatic plants to crude oil is relatively large.The Ts/Tm value of crude oil is at a moderate level,which has reached the standard of mature crude oil.The oil source in Qingyang-Zhenyuan area is compared and analyzed,indicating that Chang-8 crude oil mainly comes from Chang-7 source rock.