摘要
天然气水合物成藏系统是一个非常复杂的系统,过去的有关研究不多。为此,根据天然气水合物成藏基本条件、浅表层沉积物孔隙水地球化学特征及其所反映的气源和天然气水合物分布特征,结合刚刚结束的南海北部天然气水合物首次实钻采样成果,初步探讨了我国南海北部陆坡神狐海域天然气水合物成藏系统。结果认为:研究区温度、压力和气体组分有利于天然气水合物形成;天然气水合物在空间尺度上不均匀分布,纵向上主要分布于天然气水合物稳定带底界以上一定深度范围内;形成天然气水合物的甲烷气体很可能来源于原地微生物成因甲烷;扩散型原地生物成因甲烷产生低甲烷通量,形成了具有明显不同的分布和饱和度特征的分散型天然气水合物系统。
The reservoir system for natural gas hydrate (NGH) is very complicated and unfortunately there were not so many studies on this issue in the past years. Therefore, this study took as a case of study the samples which were first obtained by NGH drilling in the northern slope of South China Sea. According to essential factors for forming NGH reservoirs, the NGH source and distribution features reflected by intergranular water geochemical characteristics of shallow sediments, this study discussed preliminarily on the NGH reservoir system in the Shenhu area, the northern slope of South China Sea. The study showed some results as follows: (1) In the study area, temperature, pressure, and gas compositions were all favorable for the formation of NGH; (2) The high-resolution seismic data and the gas hydrate drilling getting high concentrations of hydrate (>40%) in a disseminated forms in foram-rich clay sediments showed that gas hydrate was distributed heterogeneously at all spatial scales in the study area, and the hydrate-bearing sediments ranged several ten meters in thickness were located in the lower part of gas hydrate stability zone (GHSZ), just above the bottom of gas hydrate stability zone (BGHSZ); (3) The NGH gas originated at all probability from in-situ microbiogenic methane; (4) In-situ microbial methane production resulted in a low vertical methane flux and generated a distributed NGH reservoir system with distinctive patterns of distribution and concentration within the very fine sediments.
出处
《天然气工业》
EI
CAS
CSCD
北大核心
2007年第9期1-6,共6页
Natural Gas Industry
关键词
南海北部
神狐海域
天然气水合物
气藏形成
机理
成藏系统
钻探
样品
north of South China Sea, Shenhu sea area, natural gas hydrate, gas accumulation, mechanism, reservoir system, drilling, samples
