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本文在分析研究国内外海洋底水原位探测技术的前提下，详细阐述了自主研发的“海水溶解气甲烷原位探测技术成果”的研发思路、关键技术和与国外技术的区别；结合该技术在我国南海北部水合物赋存区获得海洋底水原位甲烷测试数据以及现有分层海水技术在南海北部表层海水和台西南盆地底层海水中甲烷测试数据，进行了水合物勘探中分层海水甲烷指标地球化学特征和不同海水测量方法技术在天然气水合物勘探中指示作用的研究和评价，旨在为天然气水合物中海水地球化学勘探方法的选择和发展方向提供参考依据。结果表明：(1)表层海水溶解气甲烷异常在区域水合物远景区中具有10~50 nmol·L-1的绝对甲烷浓度和面积较大(上千km2)的区域地球化学特征；(2)底层海水甲烷异常背景值一般具有100 nmol·L-1以上的绝对甲烷浓度和面积较确定的局部地球化学异常特征；(3)海洋底水原位甲烷地球化学异常数据在水合物赋存区上的异常具有300~800 nmol·L-1左右的绝对甲烷浓度并具有高衬度异常特征。勘探技术成果显示：(1)常规技术和CTD技术获取的表层海水异常能够筛选水合物勘探远景区；(2)底水原位技术和台湾的岩心钻探技术(core top water)获取的底水地球化学异常与地下烃类聚集体渗漏相关，并有以生物成因气为主的同位素特征，因此该异常能够显示与水合物相关的甲烷渗漏地，为水合物赋存区段的识别提供依据。海水原位地球化学勘探技术在水合物海水地球化学勘探中具有广阔的应用前景。关键词：天然气水合物；海水原位探测；甲烷传感器；METS；分层海水；孔隙水
Based on the analysis of the domestic and international ocean bottom water in situ detection technology, this paper describes in detail the independent research and development of “seawater dissolved methane in situ exploration results of technology” research and development ideas, key technologies and the difference with the foreign technology; combined with the technology In situ methane test data of marine bottom water in the hydrate occurrence area in the northern South China Sea and methane data of the existing stratified seawater technology in the surface seawater in the northern South China Sea and the groundwater in the southwestern Taiwan Basin were used to study the effects of stratified seawater The research and evaluation on the geochemical characteristics of methane indicators and different seawater measurement methods in gas hydrate exploration are intended to provide reference for the selection and development of seawater geochemical exploration methods in gas hydrates. The results show that: (1) Methane anomalies in surface seawater dissolved gas have regional geochemical characteristics of 10 ~ 50 nmol·L-1 absolute methane and large area (1000 km2) in the regional hydrate prospects; (2) The background values of methane in the bottom seawater usually have the absolute methane concentration above 100 nmol·L-1 and the local geochemical anomalies with relatively definite area. (3) The data of in situ CH4 anomalies from the ocean bottom water are in the hydrate- Of the anomalies have an absolute methane concentration of about 300 to 800 nmol·L-1 and have a high-contrast anomalous characteristic. The results of the exploration technology show that: (1) the surface seawater anomalies obtained by the conventional techniques and the CTD techniques can screen the hydrate exploration prospect; (2) the bottom water in situ technique and the bottom water globe obtained by the core drilling technology in Taiwan The chemical anomaly is related to the leakage of underground hydrocarbon aggregates and has the isotopic characteristic of biogenic gas. Therefore, this anomaly can reveal the hydrate-related methane seepage and provide a basis for the identification of the hydrate-bearing segments . In situ geochemical exploration of seawater has broad application prospect in geochemical exploration of seawater of hydrate. Keywords: gas hydrate; in situ detection of seawater; methane sensor; METS; stratified seawater; pore water