柴达木盆地源自石炭系油气显示特征及其意义

Characteristics and significance of hydrocarbon shows originated from Carboniferous formation in Qaidam Basin

李会军 鄢犀利 郭娟 张林炎

中国地质科学院地质力学研究所;中原油田分公司勘探开发科学研究院;

1.Institute of Geomechanics, Chinese Academy of Geological Sciences, Beijing 100081, China; 2.Exploration&Development Research Institute of Zhongyuan Oilfield Company, SINOPEC, Puyang 457001, China

油气显示对于新区、新领域勘探具有极其重要的意义。柴达木盆地石炭系勘探程度很低,仅霍参1井、乌中1井、尕丘1井钻遇石炭系,冷科1井可能钻遇石炭系。为指明石炭系油气勘探方向,文中运用录井、油岩对比、稀有气体同位素、包裹体等多种手段寻找源自石炭系的油气显示。录井结果表明德令哈断陷、霍参1井区、尕丘地区部分油气显示来自石炭系,油岩对比表明马海、南八仙、尕丘、鱼卡地区存在地球化学特征明显有别于柴达木盆地主要烃源岩(古近系-新近系和侏罗系)的油气,稀有气体同位素研究表明南八仙和马海地区天然气源岩时代早于古近系-新近系和侏罗系,包裹体研究表明石炭系油气具有两期运聚过程。综上所述,德令哈断陷、霍参1井区、尕丘、马海、南八仙、鱼卡等地区分布有源自石炭系的油气显示,石炭系具有较大的油气勘探潜力。

Hydrocarbon shows are very important for the oil and gas exploration of new area and new fields. The Carboniferous exploration degree in Qaidam Basin is very low and only three wells including Well Huocan 1, Wuzhong 1 and Gaqiu 1 have drilled into Carboniferous formation. Well Lengke 1 may drill into Carboniferous formation. The methods of logging, oil-rock correlation, noble gas isotopic characteristics and inclusions are used to find the hydrocarbon shows originated from carboniferous formation. The hydrocarbon shows originated from carboniferous formation are found by logging in Delingha Fault Depression, Well Huocan 1
and Gaqiu Area. Oil-rock correlation shows that the oil geochemical characteristics are obviously different from that originated from Paleogene-Neogene or Jurassic formation in Mahai, Nanbaxian, Gaqiu and Yuka Area. Noble gas isotope research shows that the source rock ages of natural gas in Nanbaxian and Mahai Area are earlier than that originated from Paleogene-Neogene or Jurassic formation. Inclusions research shows that the Carboniferous oil and gas in Qaidam Basin have two -period migration and accumulation process. Thus, the hydrocarbon shows originated from Carboniferous formation are found in Delingha Fault Depression, Well Huocan 1, Gaqiu, Mahai, Nanbaxian and Yuka Area, which indicates that the Carboniferous formation in Qaidam Basin has great oil and gas exploration potential.