石油与天然气地质 ›› 2020, Vol. 41 ›› Issue (3): 558-575.doi: 10.11743/ogg20200312

• 油气地质 • 上一篇    下一篇

断裂-层序双控机制下的热液活动及成储效应——以塔里木盆地塔河、玉北地区下奥陶统为例

孙福宁1, 胡文瑄1, 胡忠亚1, 刘永立2, 康逊1, 朱峰1   

  1. 1. 南京大学 地球科学与工程学院, 江苏 南京 210023;
    2. 中国石化 西北油田分公司 勘探开发研究院, 新疆 乌鲁木齐 830011
  • 收稿日期:2018-04-02 修回日期:2020-01-18 发布日期:2020-06-16
  • 通讯作者: 胡文瑄(1959-),男,教授,博士生导师,石油与天然气地质学。E-mail:huwx@nju.edu.cn。 E-mail:huwx@nju.edu.cn
  • 作者简介:孙福宁(1994-),男,博士研究生,沉积学与石油地质学。E-mail:fnsun1228@163.com。
  • 基金资助:
    国家自然科学基金重点项目(41830425);南京大学优秀博士生提升计划B资助(201801B040)。

Impact of hydrothermal activities on reservoir formation controlled by both faults and sequences boundaries: A case study from the Lower Ordovician in Tahe and Yubei areas,Tarim Basin

Sun Funing1, Hu Wenxuan1, Hu Zhongya1, Liu Yongli2, Kang Xun1, Zhu Feng1   

  1. 1. School of Earth Sciences and Engineering, Nanjing University, Nanjing, Jiangsu 210023, China;
    2. Exploration and Production Research Institute of Northwest Oilfield Company, SINOPEC, Urumqi, Xinjiang 830011, China
  • Received:2018-04-02 Revised:2020-01-18 Published:2020-06-16

摘要: 塔里木盆地下古生界碳酸盐岩广泛发育,是油气勘探的重要领域。以塔里木盆地塔河、玉北地区下奥陶统为例,通过岩心观察、薄片鉴定、电子探针、C、O、Sr同位素以及REE元素分析,结合测井及地震资料,探讨了断裂系统和层序地层格架中的热液活动及成储效应。研究认为:中-细晶白云岩遭受富硅质热液流体改造强烈,表现为热褪色现象、鞍状白云石充填和充填白云石、方解石、玉髓、黄铁矿等多种矿物组合沉淀,以及较高的SiO2、FeO、MnO、BaO含量、较低的SrO含量和87Sr/86Sr值、偏负的δ18O值、较低的∑REE含量、明显的Eu正异常和Ce负异常。热液流体对白云岩储层的改造主要表现为溶蚀作用、重结晶作用和充填作用三个方面,溶蚀作用形成的次生溶蚀孔隙成为最重要的储集空间。不同尺度断裂和三级层序甚至更短周期层序界面共同构成深部热液流体运移的输导体系,对热液活动及储层发育起到强烈的控制作用,并建立了塔里木盆地塔河、玉北地区下奥陶统蓬莱坝组断裂-层序双控机制下的热液活动及成储效应的概念模型。

关键词: 富硅质热液, 次生溶蚀孔隙, 白云岩储层, 断裂, 层序, 下奥陶统, 塔里木盆地

Abstract: The Lower Paleozoic carbonate rocks in the Tarim Basin are widely developed,representing an important target of hydrocarbon exploration.Taking the Lower Ordovician in Tahe and Yubei areas in the Tarim Basin as examples,we discussed the impact of hydrothermal activities on reservoir formation in the fault belts and along stratigraphic framework,through core and thin section observation,electron probe microanalysis (EPMA),seismic and logging data,as well as the analyses of C,O,and Sr isotopes and REEs.The results show that medium to fine-crystalline dolomites are strongly modified by silica-rich hydrothermal fluids.A series of characteristics occurred as a result of this process,such as:thermal fading,saddle dolomite filling,and mineral precipitation including dolomite,calcite,chalcedony,pyrite and so on,as well as higher SiO2,FeO,MnO and BaO contents,lower SrO contents and 87Sr/86Sr values,more negative δ18O values,lower ∑REE contents,obvious positive Euanomalies and negative Ce anomalies.While the dolomite reservoir transformation resulted from hydrothermal fluids mainly includes dissolution,recrystallization and filling,the secondary pores with dissolution serve as the most important reservoir space.The conduit system for deep hydrothermal fluid migration is composed of faults of various scales,third-order sequences boundaries,or sequence boundaries of even shorter periods,playing a deci-sive role in controlling hydrothermal activities and reservoir development.Finally,a conceptual model displaying the impact of hydrothermal activities on reservoir formation was established under the dual control of faults and sequences boundaries in the study area.

Key words: silica-rich hydrothermal fluid, secondary dissolved pore, dolomite reservoir, fault, sequence, Lower Ordovician, Tarim Basin

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