石油与天然气地质 ›› 2017, Vol. 38 ›› Issue (6): 1087-1097.doi: 10.11743/ogg20170609

• 油气地质 • 上一篇    下一篇

鄂尔多斯盆地古隆起西侧奥陶系烃源岩评价及成藏模式

肖晖1,2, 赵靖舟1,2, 熊涛3, 吴伟涛1,2, 米敬奎4, 刘素彤1,2   

  1. 1. 西安石油大学 地球科学与工程学院, 陕西 西安 710065;
    2. 西安石油大学 陕西省油气成藏地质学重点实验室, 陕西 西安 710065;
    3. 中国石油 长庆油田分公司 第五采油厂, 陕西 西安 710200;
    4. 中国石油 勘探开发研究院, 北京 100083
  • 收稿日期:2016-12-14 修回日期:2017-10-08 出版日期:2017-12-28 发布日期:2018-01-08
  • 第一作者简介:肖晖(1980-),男,博士,副教授,油气成藏地质学。E-mail:xiaohui@xsyu.edu.cn。
  • 基金项目:
    国家自然科学基金项目（41102082）；陕西省科技厅研究发展计划项目（2012JQ5011）；陕西省教育厅重点研究计划（17JS109）。

Evaluation of Ordovician source rocks and natural gas accumulation patterns in west flank of a paleo-uplift,Ordos basin

Xiao Hui1,2, Zhao Jingzhou1,2, Xiong Tao3, Wu Weitao1,2, Mi Jingkui4, Liu Sutong1,2   

  1. 1. School of Earth Sciences and Engineering, Xi'an Shiyou University, Xi'an, Shaanxi 710065, China;
    2. Key Laboratory of Hydrocarbon Accumulation of Shannxi Province, Xi'an Shiyou University, Xi'an, Shaanxi 710065, China;
    3. No.5 Oil Production Plant, PetroChina Changqing Oilfield Company, Xi'an, Shaanxi 710200, China;
    4. PetroChina Research Institute of Petroleum Exploration & Development, Beijing 100083, China
  • Received:2016-12-14 Revised:2017-10-08 Online:2017-12-28 Published:2018-01-08

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1203

被引次数

1

摘要： 基于鄂尔多斯盆地古隆起西侧奥陶系有效烃源岩评价，证实了在该地区斜坡低部位发育有源自奥陶系内部烃源岩的气藏新类型。根据11口钻井347块烃源岩样品分析，中上奥陶统台地边缘斜坡相带发育良好烃源岩。乌拉力克组和克里磨里组烃源岩有机质TOC含量高，泥灰岩TOC含量平均值分别为0.33%和0.39%，泥质岩类TOC含量平均值分别为0.51%和0.65%，有效烃源岩累计厚度分别在12~40 m和7~14 m，局部烃源岩厚层发育区，生气强度达（14.0~15.5）×108 m3/km2，证实具有较好的生烃潜力。研究区奥陶系气藏主要经历两期成藏过程：早期为中侏罗世，奥陶系烃源岩生烃形成古油藏，晚期为晚侏罗世—早白垩世，古油藏裂解形成油型气。晚期气烃包裹体甲烷碳同位素平均值在-38.84‰，证实晚期具有油型气充注特征。古隆起西侧斜坡高部位普遍发育煤成气气藏，在克里磨里组斜坡低部位大量发育碎屑钙质角砾岩，与上覆中上奥陶统有效烃源岩近距离接触，侧向上远离奥陶系顶面风化壳，能够形成自生自储型气藏类型，如余探1井气藏。台缘斜坡带低部位发育的岩溶缝洞体，是寻找该类气藏的有利勘探目标区。

关键词: 成藏模式, 烃源岩, 奥陶系, 下古生界, 鄂尔多斯盆地

Abstract: The existence of a new gas accumulation type sourced from the source rocks within the Ordovician was confirmed at the lower slope in the west flank of a paleo-uplift in Ordos Basin based on effective source rock assessment results.Analyses of 347 samples taken from the source rock intervals in 11 wells revealed high-quality source rocks developed in marginal slopes of the middle and upper Ordovician platform in the Basin.Measurements showed that the source rocks in the Wulalike and Kelimoli Formations had relative higher TOC values,with marlite TOC averaged at 0.33% and 0.39%,and mudstone TOC averaged at 0.51% and 0.65%,respectively.The accumulative effective thicknesses of source rocks of the two formations were 12 to 40 m and 7 to 14 m,respectively.Areas with thick source rocks were assessed to have a gas generation capacity of 14.0×108 to 15.5×108 m3/km2.Gas accumulations in the Kelimoli Formation experienced two charging stages:the early stage in the Middle Jurassic,during which paleo-oil reservoirs were formed;and the late stage in the Late Jurassic to Early Cretaceous,during which the paleo-oil reservoirs were cracked into petroliferous gas reservoirs.Carbon isotopes of gas-bearing inclusions from the later stage were measured to be -38.84‰ in average,indicating late petroliferous gas charging characteristics.Coal-derived gas reservoirs were distributed widely in the upper slope in the west flank of the paleo-uplift.The fact that the massive detrital calcareous berccias formed in the Kelimoli Formation at the lower slope had a close contact with the overlying effective source rocks of the Middle and Upper Ordovician and that they stretched away laterally from the top Ordovician weathering crust,made it possible for the formation of self-sourced gas accumulations,like Yutan1 gas reservoir in the area.Fractured-vuggy karst reservoirs developed in the lower slope of the platform margin were considered to be potential exploration targets for such kind of gas reservoirs.

Key words: accumulation pattern, source rock, Ordovician, Lower Paleozoic, Ordos Basin

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