琼东南盆地华光凹陷天然气水合物稳定带厚度的影响因素  

Factors affecting the thickness of gas hydrate stability zones in the Huaguang Sag, Qiongdongnan Basin

作　　者：刘杰[1,2] 杨睿[3] 邬黛黛 金光荣[1] 张辉 Liu Jie;Yang Rui;Wu Daidai;Jin Guangrong;Zhang Hui

机构地区：[1]中国科学院广州能源研究所天然气水合物重点实验室,广东广州510640 [2]中国科学院南海生态环境工程创新研究院,广东广州511458 [3]青岛海洋地质研究所,山东青岛266071

出　　处：《海洋学报》2019年第8期13-25,共13页

基　　金：中国科学院天然气水合物重点实验室基金(Y807je1001);广州市珠江科技新星项目(201710010198);南海水合物成藏条件对比和甲烷渗漏预警研究(ISEE2018YB03);广东省促进经济发展专项资金(GDME-2018D002)

摘　　要：为了探讨琼东南盆地华光凹陷海底天然气水合物稳定带的分布规律,定量研究了静水压力、底水温度、地温梯度和气源组分对水合物稳定带的影响程度。在此基础上,分析了华光凹陷现今甲烷水合物稳定带的厚度分布。最后,综合各因素的历史演化过程,初步探讨了华光凹陷1.05MaBP以来天然气水合物稳定带的演化。结果表明:(1)气源组分和海底温度的变化对研究区内水合物稳定带的影响较大;水合物稳定带厚度与海底温度呈良好的线性负相关性。(2)水深超过600m的海域具备形成天然气水合物的温压条件;超过600m水深的海域水合物稳定带厚度大部分超过100m,其中西北部稳定带的最大厚度超过300m,是有利的水合物勘探区。(3)华光凹陷1.05MaBP以来天然气水合物稳定带厚度经历了快速增厚–窄幅变化–快速减薄和恢复的过程。麻坑群与水合物稳定变化敏感区在空间上具有较好的叠合关系。结合前人的研究成果,推测其形成与天然气水合物的分解释放有关。In order to study the distribution of gas hydrate stable zones (GHSZ) in the Huaguang Sag of Qiongdongnan Basin, the important factors affecting GHSZ's thickness are quantitatively studied, including hydrostatic pressure, bottom water temperature, geothermal gradient and gas source composition. Then, it analyzes that the thickness distribution of the present methane GHSZ in Huaguang Sag. Finally, based on the historical evolution process of above various factors, the evolution of gas hydrate stabilization zone since 1.05 Ma BP in this area is preliminarily discussed. The results show that:(1) the gas source composition and seabed temperature have a great influence on the GHSZ in the study area, and the thickness of GHSZ has a good linear negative correlation with seabed temperature;(2) the temperature and pressure conditions for gas hydrate formation are available in the Huaguang Sag of Qiongdongnan Basin, where water depth is more than 600 m, the thickness of the hydrate stability zone is more than 100 m;the thickest GHSZ is located in the northwest of the study area, with a maximum thickness of more than 300 m;it is a favorable hydrate exploration area;(3) the methane GHSZ has gone through stable stage, relatively quick incrassation, gently changing stage, and quickly attenuating and recovery stage since 1.05 Ma BP. There is a good superposition relationship between the pockmark group and the sensitive area of GHSZ. Combined with previous research results, it is concluded that their formation is related to the decomposition and release of natural gas hydrate.

关 键 词：天然气水合物 稳定带厚度 分布 演化 华光凹陷 琼东南盆地 

分 类 号：P744.4[天文地球—海洋科学]