Abstract: The platform area of Tarim Basin possesses a vast hydrocarbon resource potential in deep to ultra-deep reservoirs. Tarim Basin has experienced a complex of hydrocarbon accumulation in the Ordovician Yijianfang Formation and Yingshan Formation in Fuman oilfield. Meanwhile, there is a significant difference in the planar distribution of hydrocarbon phases. Based on micro-area U-Pb isotope dating of carbonate cement and crude oil inclusions as well as carbonate veins, this study has determined three stages of fracture-cave type vein filling in reservoirs of Fuman oilfield, three stages of crude oil charging and one stage of natural gas charging. Specifically, the Stage-1 of crude oil charging occurred during the Middle Caledonian Period (473.3-447.4 Ma), the Stage-2 spanned from the Middle Devonian to the Late Devonian Period (348.2-273.9 Ma), the Stage-3 occurred during the Early Indosinian to Yanshanian Period (217.6-205.2 Ma), and the natural gas charging occurred on a large scale during the Late Yanshanian to Himalayan (90-20 Ma). The three stages of fracture-cave type vein filling correspond to the three stages of crude oil charging and tectonic activity. There are differences in the maturity and type of paleo oils charged in the southern and northern parts of Fuman oilfield, which are primarily influenced by variations in the thermal evolution of source rocks in the Cambrian Yuertusi Formation in different areas of the oilfield. The evolutionary processes of the Cambrian source rocks and the timing of tectonic activities in the platform area exhibit temporal and spatial correlations with the four phases of hydrocarbon charging. These research findings contribute to an enhanced understanding of the hydrocarbon accumulation mechanism and hydrocarbon enrichment regularity of deep to ultra-deep carbonate reservoirs.

Key words: fluid inclusion, isotope dating, deep oil and gas, carbonate rock, Tarim Basin

摘要： 塔里木盆地台盆区深层—超深层油气资源潜力巨大,其中,富满油田奥陶系一间房组—鹰山组油气成藏过程复杂,油气相态在平面上的分布差异明显。基于碳酸盐胶结物原生油包裹体和碳酸盐脉体的微区U-Pb同位素定年结果,确定了富满油田储层充填3期缝洞型脉体,主要存在3期原油充注和1期天然气充注。第1期原油充注发生在加里东中期(473.3~447.4 Ma),第2期原油充注发生在海西中—晚期(348.2~273.9 Ma),第3期原油充注发生在印支期—燕山早期(217.6~205.2 Ma);1期天然气大规模充注在燕山晚期—喜马拉雅期(90~20 Ma);3期缝洞充填脉体对应3期原油充注时期和构造活动时间。富满油田南部与北部不同区域充注的古原油的成熟度和类型不同,主要受控于不同区域寒武系玉尔吐斯组烃源岩的热演化程度,寒武系烃源岩的热演化过程和台盆区构造活动时间与油气充注过程具有时空匹配关系。研究成果有助于提高对深层—超深层碳酸盐岩油气成藏机理和油气富集规律的认识。

关键词: 流体包裹体, 同位素定年, 深层油气, 碳酸盐岩, 塔里木盆地