石油与天然气地质 ›› 2023, Vol. 44 ›› Issue (6): 1568-1581.doi: 10.11743/ogg20230618

• 油气地质 • 上一篇    下一篇

鄂尔多斯盆地东缘上古生界致密储层含气系统压力演化

李勇1(), 朱治同1, 吴鹏2, 申陈州3, 高计县2   

  1. 1.中国矿业大学（北京） 地球科学与测绘工程学院，北京 100083
    2.中联煤层气有限责任公司，北京 100016
    3.中国石油 青海油田公司 采油一厂，青海 茫崖 816400
  • 收稿日期:2023-07-20 修回日期:2023-10-20 出版日期:2023-12-01 发布日期:2023-12-20
  • 第一作者简介:李勇（1988—），男，博士、教授，煤与煤层气地质、非常规油气地质、煤系成矿学。E-mail： liyong@cumtb.edu.cn。
  • 基金项目:
    中国石油创新基金项目(2021DQ02-1003);中央高校基本科研业务费专项(2022JCCXDC02)

Pressure evolution of gas-bearing systems in the Upper Paleozoic tight reservoirs at the eastern margin of the Ordos Basin

Yong LI1(), Zhitong ZHU1, Peng WU2, Chenzhou SHEN3, Jixian GAO2   

  1. 1.College of Geoscience and Surveying Engineering，China University of Mining and Technology （Beijing），Beijing 100083，China
    2.China United Coalbed Methane Co. Ltd. ，Beijing 100016，China
    3.No. 1 Oil Extraction Factory，Qinghai Oilfield Company，PetroChina，Mangya，Qinghai 816400，China
  • Received:2023-07-20 Revised:2023-10-20 Online:2023-12-01 Published:2023-12-20

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摘要：

鄂尔多斯盆地东缘上古生界多层系致密气发育，准确认识气藏压力演化过程对深化致密气成藏认识和实现气井高产稳产具有指导意义。综合应用钻测井资料和岩心流体包裹体测试，结合盆地埋藏史和热演化史模拟，揭示了鄂尔多斯盆地东缘上古生界含气系统压力演化。结果显示，研究区自下而上发育欠压、略微欠压和常压系统。均一温度和盐度总体上连续分布，反映了油气连续充注过程。太原组、山西组和下石盒子组均一温度和盐度正相关，反映近源生烃后快速充注；上石盒子组和石千峰组均一温度和盐度负相关，受流体远距离运移充注和紫金山构造热事件作用下的气藏再平衡影响。研究区在白垩纪中期大量生烃，形成了异常高压，储层压力在34.89 ~ 38.26 MPa。后期地层抬升造成储层压力降低，其中地层降温贡献了50.31 % ~ 57.85 %；天然气膨胀引起的气体运移贡献了28.25 % ~ 41.95 %，且以上部地层降低为主；孔隙反弹贡献了0.37 % ~ 0.79 %。相关成果系统揭示了上古生界致密气藏压力系统演化及现今气藏压力成因，对于认识鄂尔多斯盆地和类似盆地致密气富集成藏规律具有借鉴意义。

关键词: 流体包裹体, 压力系统, 致密气, 上古生界, 临兴地区, 鄂尔多斯盆地

Abstract:

Multiple tight gas reservoirs are well developed in the Upper Paleozoic sequences at the eastern margin of the Ordos Basin. An accurate understanding of the pressure evolution process of gas reservoirs will be of guiding value to gaining more insights into tight gas accumulation and achieving high and stable gas production in this region. In this study， drilling， logging， and core fluid inclusion test data， as well as simulations of burial and thermal evolution histories are integrated to reveal the pressure evolution of the Upper Paleozoic gas-bearing systems at the eastern margin of the Ordos Basin. The results show that reservoirs in the study area exhibit underpressure， slightly underpressure， and normal pressure systems from bottom to top. The homogenization temperature and salinity of fluid inclusions exhibit continuous distributions overall， suggesting a continuous hydrocarbon charging process. The Taiyuan， Shanxi， and Lower Shihezi formations demonstrate a positive correlation between the homogenization temperature and salinity of fluid inclusions， suggesting a rapid hydrocarbon charging process following near-source hydrocarbon generation. In contrast， the Upper Shihezi and Shiqianfeng formations exhibit a negative correlation between the homogenization temperature and salinity due to the long-distance fluid migration and charging， as well as the rebalancing of fluid inclusions in gas reservoirs under the influence of the Zijinshan tectono-thermal event. During the Mid-Cretaceous， the study area experienced the generation of large quantities of hydrocarbons， leading to the anomalously high reservoir pressure ranging from 34.89 ~ 38.26 MPa， followed by a decrease at later stages under the uplifting of strata. For the pressure drop， 50.31 % ~ 57.85 % was caused by the decline in formation temperature， 28.25 % ~ 41.95 % by natural gas swelling-induced gas migration （predominantly in upper strata）， and 0.37 % ~ 0.79 % by pore rebound. The findings of this study systematically reveal the pressure system evolution of the Upper Paleozoic tight gas reservoirs in the Ordos Basin and the origin of the current reservoir pressure formation. These will be of referential value to understanding the enrichment and accumulation patterns of tight gas in the Ordos Basin and the like.

Key words: fluid inclusion, pressure system, tight gas, Upper Paleozoic, Linxing area, Ordos Basin

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