石油与天然气地质 ›› 2021, Vol. 42 ›› Issue (4): 841-851.doi: 10.11743/ogg20210406

• 油气地质 • 上一篇    下一篇

四川盆地新场构造带上三叠统须家河组二段地层水化学动态特征及其成因

楼章华1(), 苏一哲1, 朱蓉1,*(), 刘一锋1, 徐士林2, 李王鹏2   

  1. 1. 浙江大学 海洋学院, 浙江 舟山 316021
    2. 中国石化 石油勘探开发研究院, 北京 100083
  • 收稿日期:2020-10-14 出版日期:2021-08-28 发布日期:2021-08-27
  • 通讯作者: 朱蓉 E-mail:iwr@zju.edu.cn;zhurong@zju.edu.cn
  • 第一作者简介:楼章华(1963-), 男, 教授, 博士生导师, 地质流体与油气成藏、保存研究。E-mail: iwr@zju.edu.cn
  • 基金项目:
    国家自然科学基金项目(41572110)

Dynamic chemical characteristics and origin of formation water in the second member of Xujiahe Formation, Xinchang structural belt, Sichuan Basin

Zhanghua Lou1(), Yizhe Su1, Rong Zhu1,*(), Yifeng Liu1, Shilin Xu2, Wangpeng Li2   

  1. 1. Ocean College, Zhejiang University, Zhoushan, Zhejiang 316021, China
    2. Petroleum Exploration and Production Research Institute, SINOPEC, Beijing 100083, China
  • Received:2020-10-14 Online:2021-08-28 Published:2021-08-27
  • Contact: Rong Zhu E-mail:iwr@zju.edu.cn;zhurong@zju.edu.cn

摘要:

四川盆地新场构造带须家河组二段(须二段)地层水化学特征复杂,矿化度分布范围广,部分井在生产过程中地层水化学特征发生动态变化。因此,利用矿化度、氯镁系数、变质系数和诺瓦克相图等分析了须家河组各层段地层水化学特征,探讨了地层水的动态运移。结果显示:须二段地层水矿化度主要集中在70~110 g/L,氯镁系数大于50,变质系数大于10;须四段地层水矿化度主要集中在50~90 g/L,氯镁系数小于50,变质系数小于10;两者诺瓦克相图也具有明显差异。上述特征可作为地层水分布层系判别指标。须二段大部分井在生产过程中水化学特征较为稳定,表明地层水来源较为一致,以同层水为主;部分井如新856井、新2井、新10-1H井和新5井在生产过程中地层水化学特征发生了显著变化,根据判别指标,其地层水来源发生了变化。新2井和新856井在汶川地震后均有高矿化度、高溴离子浓度雷口坡组海相地层水混入;新10-1H井和新5井在生产过程中有须四段地层水进入,断层可能为地层水的跨层运移提供了通道。

关键词: 氯镁系数, 变质系数, 矿化度, 诺瓦克相图, 地层水动态变化, 须家河组, 四川盆地

Abstract:

Formation water from the second member of Xujiahe Formation, Xinchang structural belt, Sichuan Basin, is chemically complicated and highly variable in salinity, with some wells recording dynamic changes of chemical characteristics of produced waters.This paper discusses the migration of formation water based on a thorough analysis of the chemical characteristics of formation water from each interval of the Xujiahe Formation by using salinity data, chlorine/magnesiumionic ratios, metamorphism coefficients, Novák's phase diagrams and etc. The results show that the formation water of the second member has salinity values ranging between 70 and 110 g/L, chlorine/magnesium ionic ratios greater than 50 and metamorphic coefficients greater than 10; and that of the fourth member has salinity values ranging between 50 and 90 g/L, chlorine/magnesium ionic ratios less than 50 and metamorphism coefficients less than 10.Their Novak's phase diagrams also have obvious differences.These characteristics can be used to determine the stratigraphic origins of formation waters.The produced water from most wells in the second member show relatively stable chemical characteristics, indicating that the waters are sourced from the same stratigraphic interval. However, the produced water from some wells, such as Xin 856, Xin 2, Xin 10-1H and Xin 5, show significant variation of chemical characteristics. Judging by the graphs, the waters are multi-sourced. Alien waters of high salinity and high bromide ion concentration from marine Leikoupo Formation had been detected in wells Xin 2 and Xin 856 after Wenchuan Earthquake. Waters from the fourth member were also observed in wells Xin 10-1H and Xin 5.It is suggested that faults are the most likely pathways for this cross-layer migration of formation water.

Key words: chlorine/agnesium ratio, metamorphism coefficient, salinity, Novák's phase diagram, formation water dynamic change, Xujiahe Formation, Sichuan Basin

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