海域天然气水合物相关的流体运移及海底甲烷渗漏研究  

Fluid migration and seabed methane seepage associated with marine gas hydrate systems.Earth Science Frontiers

作　　者：杨金秀 王琛 邢兰昌[3] 魏伟[4] 张伟[1] 韩维峰 赵丽 刘坤一 YANG Jinxiu;WANG Chen;XING Lanchang;WEI Wei;ZHANG Wei;HAN Weifeng;ZHAO Li;LIU Kunyi(National Engineering Research Center of Gas Hydrate Exploration and Development,Guangzhou 511458,China;School of Geosciences,China University of Petroleum(East China),Qingdao 266580,China;College of Control Science and Engineering,China University of Petroleum(East China),Qingdao 266580,China;New Energy Institute,Research Institute of Petroleum Exploration and Development(RIPED),Langfang 065007,China)

机构地区：[1]天然气水合物勘查开发国家工程研究中心,广东广州511458 [2]中国石油大学(华东)地球科学与技术学院,山东青岛266580 [3]中国石油大学(华东)控制科学与工程学院,山东青岛266580 [4]中国石油勘探开发研究院新能源研究所,河北廊坊065007

出　　处：《地学前缘》2025年第2期113-125,共13页Earth Science Frontiers

基　　金：天然气水合物勘查开发国家工程研究中心开放基金项目(NERCY[202401]);中石油"十四五"前瞻性基础性重大科技项目(2021DJ4901);国家自然科学基金项目(42476070)。

摘　　要：认清地质历史时期相关的流体运移和海底甲烷渗漏是天然气水合物研究中的重要问题,对了解水合物成藏、评价水合物分解过程中甲烷渗漏可能造成的环境影响有重要指导作用。本文通过对全球海域大量天然气水合物发育区进行再解释,分析流体运移通道、海底甲烷渗漏与天然气水合物系统三者间的关系。首先,按照流体运移通道在水合物系统中的作用将其分为两类:类型Ⅰ主要分布在水合物稳定区底界(BSR)之下,为水合物系统成藏提供气源的通道,类型Ⅱ分布在BSR以浅,甚至延伸至海底,为水合物系统中的甲烷逃逸提供渗漏通道。另外,分析认为多边形断层作为通道疏导油气垂向运移的作用是有限的。其次,根据海底甲烷渗漏与天然气水合物系统的位置关系以及渗漏的甲烷气源条件,将海底甲烷渗漏特征分为三大类五小类:水合物稳定边界以深(水合物系统气源、非水合物系统气源)、水合物稳定边界附近(水合物系统气源、非水合物系统气源)和水合物稳定边界以浅(非水合物系统气源)。其中,水合物稳定区向陆分布边界LLGHSZ(landward limit of gas hydrate stability zone)附近的甲烷渗漏强度和密度最大。综上,本文提出的流体运移通道与海底甲烷渗漏特征的分类方法对认识动态天然气水合物系统的成藏和分解过程、评价相关的环境和气候影响具有一定的指导作用。It is crucial for comprehending the accumulation mechanisms of gas hydrates and assessing the potential environmental impacts caused by their dissociation and associated methane seepage to understand fluid migration processes and seabed methane seepage in gas hydrate studies.This paper analyzes the relationships between fluid migration conduits,seabed methane seepage,and gas hydrate systems by examining numerous gas hydrate case studies worldwide.Fluid migration conduits are categorized into two types based on their roles in the gas hydrate system.Type I conduits are primarily distributed below the bottom simulating reflector(BSR)and serve as gas sources for the gas hydrate system.Type II conduits are in sediments above the BSR and may extend to the seabed,acting as pathways for gas leakage from the gas hydrate system.The role of polygonal faults as fluid migration conduits is considered limited,mainly contributing to the accumulation of shallow gas and gas hydrates.Seabed methane seepage is classified into three categories and five subcategories based on the spatial relationship between methane seepage,the gas hydrate system,and gas source conditions:(1)Deeper than the landward limit of the gas hydrate stability zone(LLGHSZ):(Hydrate-related gas source and non-hydrate-related gas source);(2)Around the LLGHSZ(Hydrate-related gas source and non-hydrate-related gas source);(3)Shallower than the LLGHSZ(Non-hydrate-related gas source).The intensity and density of methane leakage are highest near the LLGHSZ.This classification of fluid migration conduits and seabed methane seepage provides a framework for understanding the dynamic processes of gas hydrate accumulation and dissociation.It also offers insights into evaluating the environmental and climatic impacts associated with gas hydrate systems.

关 键 词：天然气水合物 BSR(水合物稳定区底界) 向陆分布边界 流体运移 海底甲烷渗漏 

分 类 号：P738[天文地球—海洋地质] P631[天文地球—海洋科学]