Abstract: Based on the study of biomarkers,the oil from L-oil field located on Dongs-ha aplift of pearl River Mouth Basin in China Most of oils from the margins and the surrounding sags of this aplift have similar maturity,same terpenoid distribution,and contain high abundance of 4-methyl-C₃₀ sterane.These oils are derived from Eocene lacustrine source rocks of Wenchang formation in these sags.The migration parameters of L-oil are much larger than those of the oils discovered in the margins of this aplift,and the carbon isotopes of the saturated alkanes and the aromatics of the L-oil are also lighter than that of the others,these geochemical characteristics indicate that the L-oil underwent a long distance migration.Dongsha aplift is a long time paleo-uplift,having developed basal faults and fractures surrounding the aplift,having an extensive distribution of high porosity marine sandstone and bioherm limestone,and having stable thick regional capping beds.These special geological conditions make the oilstomigrate for a long distance and accumulate enormously in the highs of the basin and form the big L-oil field with a considerable amount of reserve.

摘要： 生物标志化合物研究表明,在我国南海珠江口盆地东沙隆起上发现的L油田原油与隆起边缘及周围凹陷中的大多数原油成熟度相近,都含有异常丰富的4-甲基-C₃₀甾烷,萜烷的分布模式也极为相似,证明二者同源,均源自凹陷中的始新统文昌组湖相生油岩,L油田原油的运移参数远远大于隆起边缘所发现的原油,饱和烃和芳烃的碳同位素值也表现了偏轻的特点,这些地化特征是L油田原油经历了长距离运移的证据;东沙隆起是长时期的古隆起、隆起周围基底断裂发育、隆起之上高孔隙海相砂岩、生物礁灰岩广布,其上又有厚层稳定的区域盖层,这种特定的地质条件促使凹陷中生成的原油得以长距离运移并大规模聚集在盆地的最高部位,形成储量可观的L大油田.

关键词: 中国, 陆相盆地, 原油, 油气运移, 生物标记化合物, 珠江口盆地