北京大学学报自然科学版 ›› 2021, Vol. 57 ›› Issue (1): 99-110.DOI: 10.13209/j.0479-8023.2020.091

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海域天然气水合物开采的4C-OBC时移地震动态监测模拟

朱贺1,2, 何涛1,2,†, 梁前勇3, 吴学敏3, 董一飞3   

  1. 1. 造山带与地壳演化教育部重点实验室, 北京大学地球与空间科学学院, 北京 100871 2. 北京天然气水合物国际研究中心, 北京 100871 3. 中国地质调查局广州海洋地质调查局, 广州 510760
  • 收稿日期:2020-01-04 修回日期:2020-05-09 出版日期:2021-01-20 发布日期:2021-01-20
  • 通讯作者: 何涛, E-mail: taohe(at)pku.edu.cn
  • 基金资助:
    国家自然科学基金(41676032, 40904029)和中国地质调查局国家天然气水合物专项基金(DD20190218, DD20160217, DD20189320, HDJJHT-20)资助

Modeling for Dynamic Monitoring of Marine Gas Hydrate Exploitation Using 4C-OBC Time-lapse Seismic System

ZHU He1,2, HE Tao1,2,†, LIANG Qianyong3, WU Xuemin3, DONG Yifei3   

  1. 1. Key Laboratory of Orogenic Belts and Crustal Evolution (MOE), School of Earth and Space Sciences, Peking University, Beijing 100871

    2. Beijing International Center for Gas Hydrate, Beijing 100871

    3. Guangzhou Marine Geological Survey, China Geological Survey, Guangzhou 510760

  • Received:2020-01-04 Revised:2020-05-09 Online:2021-01-20 Published:2021-01-20
  • Contact: HE Tao, E-mail: taohe(at)pku.edu.cn

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摘要：

为了掌控海域天然气水合物开采过程中的地质和环境风险, 采用能够同时采集纵波信号和横波信号, 并且满足实时性和长期性要求的四分量海底震缆(4C-OBC)技术, 对天然气水合物储层进行时移地震动态监测。针对未来天然气水合物商业化开发时的水平井环境, 通过射线追踪方法进行正演模拟, 对地层模型进行地震照明分析, 得到合理的4C-OBC布设参数, 以期确保采集的地震数据具有良好的成像效果, 并对不同开发阶段的时移地震数据进行走时与振幅分析。结果显示, 差异走时与差异振幅均能很好地反映天然气水合物的开采程度, 其中转换横波的效果更显著。观测系统的误差分析结果表明, 震源船的定位误差不会对这套时移监测系统有明显的影响。总的来说, 采用4C-OBC时移地震对天然气水合物储层进行动态监测的方案是有效的。

关键词: 四分量海底震缆(4C-OBC), 动态监测, 时移地震, 天然气水合物, 射线追踪

Abstract:

In order to control the geological and environmental risks during the exploitation of marine gas hydrate, 4-component ocean bottom cable (4C-OBC) is considered to perform time-lapse seismic monitoring on hydrate reservoirs, which can collect P- and S-wave simultaneously, and satisfy the requirement of real-time and long-term monitoring. This paper uses ray tracing method to carry out forward simulation of 4C-OBC time-lapse seismic system for the horizontal well environment in the future commercial gas hydrate exploitation. Based on the seismic illumination of the formation model, the optimal OBC layout parameters is obtained to ensure that the acquired seismic data has good imaging effect. Then, the travel time and amplitude of the time-lapse seismic data in different exploitation stages is analyzed. The results show that both differential travel time and amplitude could reflect the exploitation degree of gas hydrate reservoir, especially significant for converted S-wave. The error analysis results of the observation system show that seismic source vessel’s positioning error would not significantly affect the time-lapse monitoring system. In sum, it is effective to monitor dynamic process of marine gas hydrate reservoir using 4C-OBC time-lapse seismic system.

Key words: 4-component ocean bottom cable (4C-OBC), dynamic monitoring, time-lapse seismic, natural gas hydrate, ray tracing

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