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塔中Ⅰ号坡折带45个原油样品的地球化学分析表明,原油富含轻烃组分、贫重质组分,反映源岩较高的热成熟度。原油中发育异常高丰度的含硫芳烃-二苯并噻吩,反映了海相成因特征。伽马蜡烷/C30藿烷、规则甾烷与C30甾烷相对分布等多项指标与生物标志物指纹反映区内至少有两种油源。双金刚烷系列与链烷烃分布指示塔中Ⅰ号坡折带东端存在一强气侵注入点。观察到邻井原油、不同层系原油烃类化学成分显著的差异,指示油气成因与成藏条件的差异。塔中Ⅰ号坡折带油气的地球化学特征反映了叠合盆地海相成因油气的普遍特征,包括高过成熟性、多源与多期成藏、油气化学成分的非均一性及油气藏的相对分隔性。本研究为区内寻找多种成因类型油气与油源确认提供了依据,指示塔中低凸起油气勘探潜力巨大。
Geochemical analysis of 45 crude oil samples from Tazhong Ⅰ slope break shows that the crude oil is rich in light hydrocarbon components and poor heavy components, reflecting the high thermal maturity of the source rocks. Abnormal abundance of sulfur-containing aromatics in crude oil, dibenzothiophene, reflects the marine facies characteristics. Gamma wax / C30 hopane, the relative distribution of regular sterane with C30 sterane and other indicators and fingerprints of biomarkers reflect the region at least two sources of oil. There is a strong gas intrusion point in the east end of the diphyroid zone and paraffin distribution indicator tower. Significant differences were observed in the chemical composition of hydrocarbons in adjacent wells and in different layers of crude oil, indicating the differences in hydrocarbon genesis and reservoir forming conditions. The geochemical characteristics of oil-gas in Tazhong Ⅰ slope-break zone reflect the general characteristics of marine-derived hydrocarbon in the superimposed basin, including over-maturity, multi-source and multi-phase accumulation, heterogeneity of hydrocarbon chemical composition, Relative separation. This study provides a basis for the identification of oil and gas sources of various genetic types in the area, indicating that there is a great potential for hydrocarbon exploration in low-relief areas in the indicator tower.