鄂尔多斯盆地西峰地区延长组烃源岩干酪根地球化学特征

为了确定鄂尔多斯盆地西南部西峰地区延长组烃源岩有机质类型及其生烃潜力，对长8-长7段烃源岩干酪根显微组分、元素组成和碳同位素组成进行了研究。分析表明，长7段（尤其是长7^2和长7^3段）烃源岩有机质类型好，包括大量的腐泥型和腐殖-腐泥型有机质，是形成于深湖相还原环境的富有机质沉积，代表高生产率阶段藻类母质输入特征。由于湖底浊流的影响，长7^3段烃源岩混入较多的陆源高等植物母质。长8段烃源岩有机质类型较差，以混合型有机质为主，形成于靠近陆源的滨浅湖相，既有陆源高等植物母质输入，又有部分藻类母质输入，由于沉积环境的差异，部分井内样品以腐殖型有机质为主。延长组长7^2-长7^3段烃源岩具有很好的生烃潜力，是本区油藏已发现原油的可能来源。图4表2参15

Geochemical characteristics of kerogen in Yanchang Formation source rocks, Xifeng area, Ordos Basin

The kerogen's maceral, elements and carbon isotopes in the Chang 7 and Chang 8 source rocks of the Yanchang Formation, Xifeng area, southwestern Ordos Basin, suggest that the organic matter types in the Chang 7-2 and Chang 7-3 are good, containing sapropel and sapropel-humic kerogens,which are formed in a deep lake with a reducing environment and indicate algae input in productive period. The Chang 7-3 source rocks contain many terrestrial plant remnants due to turbidite sediments. The Chang 8 source rocks have worse organic matter type, mainly mixed type, formed in a shallow lake, with both terrestrial plant remnants and some algae input. Because of the difference of the sedimentary and preservation environments, the Chang 8 source rocks at some wells have mainly humic kerogen. The source rocks of the Chang 7-2 and Chang 7-3 have good potential for oil and gas, and are probably the main source for the oil reservoirs.