海底沉积物中气体迁移过程分析及监测技术研究进展  

Progress in analysis and monitoring technology for gas migration in submarine sediments

作　　者：孙浩 郭秀军[1,2,3] 吴景鑫 SUN Hao;GUO XiuJun;WU JingXin(College of Environmental Science and Engineering,Ocean University of China,Qingdao 266100,China;Shandong Provincial Key Laboratory of Marine Environment and Geological Engineering,Qingdao 266100,China;Key Laboratory of Marine Environmental Science and Ecology,Ministry of Education,Qingdao 266100,China)

机构地区：[1]中国海洋大学环境科学与工程学院,青岛266100 [2]山东省海洋环境地质工程重点实验室,青岛266100 [3]海洋环境与生态教育部重点实验室,青岛266100

出　　处：《地球物理学进展》2022年第2期869-881,共13页Progress in Geophysics

基　　金：国家自然科学基金“近海浅层气电阻率成像法探测技术研究”(41772307);国家重点研发计划“天然气水合物试采区土力学性质原位监测技术”(2017YFC037701)联合资助.

摘　　要：海底沉积物中的气体迁移作为全球变暖、海洋地质灾害以及海洋工程安全的重要影响因素,近年来一直受到学界和业界的高度关注.本文综述了海底沉积物中气体的生长及迁移机制,并对现有的海底浅层气监测方法进行了梳理.已有的实验证据表明,孤立气泡和连续气体作为气体在沉积物中的两种分布形态,具有不同的迁移方式.气泡在经历沉积物孔隙尺度的生长过程后,通过使周围沉积物弹性膨胀与拉伸断裂交替循环的方式继续生长,当气泡生长到一定尺寸时,其将在“伪浮力”的作用下开始向上迁移,整个过程可以通过线弹性断裂力学(LEFM)理论进行描述.连续气体在沉积物中的迁移主要通过毛细侵入和劈裂侵入两种方式,前者多存在于粗粒沉积物中,而后者多存在于细粒沉积物中,两种迁移方式主要受控于沉积物颗粒尺寸、应力环境等因素.沉积物中气体迁移的监测方法主要有CT技术、气体压力监测、孔压监测、海洋地震法以及海洋电阻率法等,其中CT技术和气体压力监测多应用于实验室尺度,而原位尺度的海底浅层气研究多通过海洋地震法及海洋电阻率法等地球物理勘探手段进行观测.As an important factor affecting global warming,marine geological disasters,and the safety of marine engineering construction,gas migration in submarine sediments has received a great deal of attention from academia and industry in recent years.This article reviews the growth and migration mechanisms of gas in seafloor sediments and evaluates the existing methods for monitoring of shallow gases.Existing experimental evidence shows that the two forms of gas distribution in sediments,isolated bubbles and continuous gas,have different migration modes.After a bubble undergoes the growth process in the pores of sediments,it will continue to grow through alternating cycles of elastic expansion and tensile fracture until reaching a certain size,at which time it will start to rise under the action of“pseudo-buoyancy.”The whole process can be described by the Linear Elastic Fracture Mechanics(LEFM)theory.The migration of continuous gas in sediments mainly occurs through capillary invasion and fracture opening,with the former being found primarily in coarse-grained sediments and the latter in fine-grained sediments.The two migration modes are mainly controlled by sediment grain size,stress,and other factors.The main methods for monitoring gas migration in sediments include Computed Tomography(CT)technology,gas pressure monitoring,pore pressure monitoring,marine seismic methods,and marine resistivity methods.CT technology and gas pressure monitoring are mostly applied at the laboratory scale,while the in-situ measurement of submarine shallow gas is mostly observed by means of geophysical exploration such as the marine seismic method and marine resistivity method.

关 键 词：海底沉积物 气体 迁移机制 监测技术 

分 类 号：P631[天文地球—地质矿产勘探] P738[天文地球—地质学]