High-resolution seismic characterization of the gas and gas hydrate system at Green Canyon 955, Gulf of Mexico, USA
High-resolution seismic characterization of the gas and gas hydrate system at Green Canyon 955, Gulf of Mexico, USA
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DOI：
10.1016/j.marpetgeo.2017.01.029
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发表时间：
2017-04
影响因子：
4.2
通讯作者：
S. Haines;P. Hart;T. Collett;W. Shedd;M. Frye;P. Weimer;R. Boswell
中科院分区：
文献类型：
--
作者：
S. Haines;P. Hart;T. Collett;W. Shedd;M. Frye;P. Weimer;R. Boswell
墨西哥湾绿色峡谷955（GC 955）至少区块的上新世和更新世沉积物包括富含砂的地层，具有高饱和度的气体水合物;在过去十年中，已使用常规工业三维（3D）地震数据和专用随钻测井（LWD）钻孔数据对这些气体水合物积聚和相关地质进行了表征。为了改善构造和地层特征，并解决气流和储层性质的问题，2013年美国地质调查局在GC 955获得了高分辨率二维（2D）地震数据。对所有可用数据的综合分析提高了我们对研究区地质演化的理解，其中包括密西西比河沉积物流入的盆地规模迁移以及GC 955处沉积通道的局部规模移动，以响应盐驱动的隆起，与盐隆起相关的构造变形，天然气从较深的沉积物向上运移，充注主要的天然气水合物储层和较浅的地层。2D数据证实，富砂储层主要由沉积在近端堤坝环境中的沉积物组成，河道冲刷的事件，穿插堤坝沉积，导致许多单独的近端堤坝存款“豆荚”的组合，每个豆荚的水平范围可达数百米。2D和3D数据的联合分析揭示了控制流体流动系统的复杂断层网络的新细节;大型东西向正断层允许流体流过密封细粒单元，较小的南北向断层提供了通过较浅沉积物的集中流体流动路径（烟囱）。在GC 955的最近历史中，该系统使天然气从主储层流向海底，其复杂性有助于解释天然气水合物在中间地层中的分布。
The Pliocene and Pleistocene sediments at lease block Green Canyon 955 (GC955) in the Gulf of Mexico include sand-rich strata with high saturations of gas hydrate; these gas hydrate accumulations and the associated geology have been characterized over the past decade using conventional industry three-dimensional (3D) seismic data and dedicated logging-while-drilling (LWD) borehole data. To improve structural and stratigraphic characterization and to address questions of gas flow and reservoir properties, in 2013 the U.S. Geological Survey acquired high-resolution two-dimensional (2D) seismic data at GC955. Combined analysis of all available data improves our understanding of the geological evolution of the study area, which includes basin-scale migration of the Mississippi River sediment influx as well as local-scale shifting of sedimentary channels at GC955 in response to salt-driven uplift, structural deformation associated with the salt uplift, and upward gas migration from deeper sediments that charges the main gas hydrate reservoir and shallower strata. The 2D data confirm that the sand-rich reservoir is composed principally of sediments deposited in a proximal levee setting and that episodes of channel scour, interspersed with levee deposition, have resulted in an assemblage of many individual proximal levee deposit “pods” each with horizontal extent up to several hundred meters. Joint analysis of the 2D and 3D data reveals new detail of a complex fault network that controls the fluid-flow system; large east-west trending normal faults allow fluid flow through the reservoir-sealing fine-grained unit, and smaller north-south oriented faults provide focused fluid-flow pathways (chimneys) through the shallower sediments. This system has enabled the flow of gas from the main reservoir to the seafloor throughout the recent history at GC955, and its intricacies help explain the distributed occurrences of gas hydrate in the intervening strata.