南海东北部陆坡水合物钻探区BSR推导流体运移速率研究

发布时间：2018-03-03 11:19

本文选题：南海东北部陆坡　切入点：天然气水合物　出处：《地学前缘》2017年04期 　论文类型：期刊论文

【摘要】：2013年广州海洋地质调查局在我国南海东北部陆坡海域实施天然气水合物钻探,获取了多种类型的高纯度水合物实物样品,进一步表明了南海存在丰富的天然气水合物资源前景。在此钻探之前,通过多年的地球物理、地球化学以及地质综合调查工作,积累了大量与天然气水合物赋存相关的各种地质数据。本文利用1D流体运移模型,结合热流站位的温压场数据以及多道地震数据所反映的BSR信息,计算了各个有效热流站位的流体运移速率,并结合钻探区的地质构造背景和钻探井位天然气水合物层位的分布情况,分析了流体运移速率分布特征,初步阐释了流体运移速率、构造背景以及与天然气水合物形成的相互关系。计算结果表明,钻探区流体运移速率数据分布区间为-25~+38cm/a,反映了钻探区构造背景相对复杂。流体运移速率分布具有规律性,主要受到断层和气烟囱的类别控制,可分为两大类。第一类为位于钻探区北部高地的继承性断层,断面直立陡倾并部分切穿海底,伴有大型气烟囱顶部或数量众多的侧翼小型活动正断层,为深部大规模流体运移提供了充足通道。受此类地质条件控制的流体运移速率表现为幅值波动较大,天然气水合物多发育在海底浅层,且呈现多层分布。第二类为位于钻探区西南部以及东部较大水深的滑动断层以及小型气烟囱,断层主体表现断层面清晰,断面较缓,刺穿尺度较短,气烟囱发育也比较晚,一定程度上限制了来自深部流体运移的规模。受此类地质条件控制的流体运移速率表现较为缓和,流体运移速率波动范围小,天然气水合物多发育在海底深层。
[Abstract]:In 2013, Guangzhou Marine Geological Survey carried out natural gas hydrate drilling in the northeastern slope of the South China Sea. It is further indicated that the South China Sea is rich in natural gas hydrate resources. Prior to this drilling, comprehensive geophysical, geochemical and geological surveys were carried out for many years. A large number of geological data related to the occurrence of natural gas hydrate have been accumulated. In this paper, we use the 1D fluid migration model, combined with the temperature and pressure field data of the heat flow station and the BSR information reflected by the multi-channel seismic data. The fluid migration rate of each effective heat flow station is calculated. Combined with the geological structure background of drilling area and the distribution of gas hydrate in drilling well site, the distribution characteristics of fluid migration rate are analyzed, and the fluid migration rate is preliminarily explained. The results show that the distribution range of fluid migration rate data in drilling area is -25 ~ 38 cm / a, which indicates that the tectonic background in drilling area is relatively complex, and the distribution of fluid migration rate is regular. Mainly controlled by the types of faults and gas chimneys, they can be divided into two categories. The first is a succession fault located in the northern highlands of the drilling area, with a vertical steep dip of sections and partial cutting through the seabed. The small active normal faults on the flanks with the top of large gas chimneys or a large number of them provide sufficient channels for large-scale deep fluid migration. The fluid migration rates controlled by such geological conditions are characterized by large amplitude fluctuations. The natural gas hydrate mostly develops in the shallow layer of the seabed and presents multi-layer distribution. The second kind is the sliding fault and small gas chimney located in the southwest and east of the drilling area, the fault body shows clear fault plane and the section is slow. The impinging scale is relatively short and the gas chimney develops late, which limits the scale of fluid migration from the deep to some extent. The fluid migration rate controlled by such geological conditions is relatively mild, and the fluctuation range of fluid migration rate is small. Gas hydrates are mostly developed in deep seabed.
【作者单位】：广州海洋地质调查局国土资源部海底矿产资源重点实验室;
【基金】：国土资源部国家专项(GZH201100303,GZH201100305) 国家高技术研究发展计划“863”项目(2013AA092501) 国家自然科学基金项目(91428205)
【分类号】：P618.13

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