摘要
海底天然气水合物区的冷泉系统中流体在运移过程中会冲击浅部地层,使下部地层中的流体物质发生“固-液-气”转化,其释放的能量导致裂隙坍塌和孔隙破裂,进而产生一系列与冷泉活动相关的微地震信号。这些微地震信号能够直观准确地反映天然气水合物区冷泉系统的生长发育状态及生命周期,揭示其流体逸散活动规律。本文研究了琼东南海域“海马”冷泉区2014和2021年的两次不同时间监测到的地震数据,经过相应的预处理,利用长短时窗能量比方法识别出了大量与冷泉活动相关的微地震事件。通过对这些微地震信号的波形、频谱特征和时间分布特征分析,了解了琼东南海域天然气水合物区冷泉微地震事件的响应特征。初步研究结果表明,“海马”冷泉区的冷泉活动产生的微地震事件包括短扰动信号和典型的冷泉微地震信号;波形尾部呈现类似指数的有规律的衰减,持续时间为0.3~2 s,主频分布在4~26 Hz以内。微地震活动不存在明显的类似潮汐的时间分布规律,多呈现短期集中分布的特点,这可能与冷泉喷口的活动及活动的强弱有关。
During the migration,fluid in the cold seep system of the submarine natural gas hydrate area will impact the shallow strata,causing the fluid material in the lower strata to undergo a"solid-liquid-gas"transformation.The energy released could cause fracture collapse and pore rupture,thereby generating a series of vibration events.These microseismic signals can visually and accurately reflect the growth and development status and life cycle of the cold seep system,and reveal the laws of its fluid escape activities.We studied the microseismic data monitored at two different times in 2014 and 2021 near the Haima cold seep area in the Qiongdongnan waters.After preprocessing the data,a large number of microseismic events related to cold seep activities were identified using the STA/LTA(short term average/long term average)method.By analyzing the characteristics of waveform,spectrum,and time distribution of these microseismic signals,the response characteristics of the cold seep microseismic events in the natural gas hydrate area in the Qiongdongnan waters were clarified.Preliminary research results show that the microseismic events generated by the cold seep activity in the Haima cold seep area include short duration events and typical cold seep microseismic signals;the tail of the waveform shows a regular and exponential-like decay,with a duration of 0.3~2 s and a main frequency range of 4~26 Hz.There is no obvious tidal-like time distribution pattern for cold seep microseismic activity,and it mostly shows the characteristics of short-term concentrated distribution,which may be related to the activity and strength of the cold seep vents.
作者
胡广
黄建宇
杨胜雄
李沅衡
田冬梅
曹荆亚
周军明
邓雨恬
HU Guang;HUANG Jianyu;YANG Shengxiong;LI Yuanheng;TIAN Dongmei;CAO Jingya;ZHOU Junming;DENG Yutian(Southern Marine Science and Engineering Guangdong Laboratory(Guangzhou),Guangzhou 511458,China;Guangzhou Marine Geological Survey,Guangzhou 511458,China)
出处
《海洋地质与第四纪地质》
CAS
CSCD
北大核心
2024年第6期12-24,共13页
Marine Geology & Quaternary Geology
基金
国家自然科学基金“南海北部高富集天然气水合物储层特征与成藏控制机理研究”(U2244224)
广州市基础研究计划与基础应用研究项目“基于深度学习的冷泉羽状流地震资料高分辨率处理方法研究”(2023A04J0917)
南方海洋科学与工程广东省实验室(广州)引进高端人才项目(GML2020GD0802)。
关键词
天然气水合物
“海马”冷泉
微地震事件
短时信号
琼东南海域
natural gas hydrate
Haima cold seep
microseismic events
short duration event
Qiongdongnan sea area
作者简介
胡广(1988-),男,博士,主要从事天然气水合物地震响应特征分析研究,E-mail:huguang@gmlab.ac.cn;通讯作者:杨胜雄(1964-),男,博士,正高级工程师,主要从事大洋矿产资源调查研究、海洋地质地球物理研究,E-mail:yangsx@gmlab.ac.cn。
