北极波弗特—马更些三角洲盆地天然气水合物成藏模式

Accumulation model of natural gas hydrate in the Beaufort-Mackenzie Delta Basin, the Arctic

  • 摘要: 北极波弗特—马更些三角洲盆地常规油气和水合物资源十分丰富,是全球开展天然气水合物调查研究最早的地区之一。对该盆地水合物和常规油气的共生共藏关系的研究,不但对能源资源的勘探具有直接价值,而且对海域工程施工中海底稳定性评价以及全球气候变化和碳循环研究具有重要的理论和实际意义。在大量文献资料综合分析的基础上,系统总结了影响水合物成藏的地质和稳定条件,结合极地冰川演化特征,提出水合物与下伏油气藏渗漏共生并受冻土调节的成藏模式。认为波弗特—马更些三角洲盆地天然气水合物气源主要为下伏含油气系统中的热成因烃气;构造要素(断裂、背斜)密度与水合物富集丰度呈正相关,水合物赋存主要与Iperk、Kugmallit和Richards组的三角洲平原相砂体有关;水合物稳定带之上的冻土带对天然气水合物的成藏起着关键性调节作用。

     

    Abstract: The Beaufort-Mackenzie Delta is an Arctic basin which contains abundant conventional hydrocarbon and natural gas hydrate. It is also one of the earliest regions in the world to carry out producing test of natural gas hydrate. To study the coexistence relationship between the hydrate and conventional hydrocarbon in the basin has not only direct significance to energy resource exploration, but also important theoretical and practical significance to seabed stability assessment, global climate change and carbon cycle research. In this paper, geological factors and stability conditions for hydrate reservoir generation was systematically summarized based on the large number of data available. Furthermore, combined with the analysis of glacier evolution, it was concluded that the accumulation of natural gas hydrate in the basin is controlled by the leakage of the underlying petroleum system and the change in permafrost zone. It is revealed that the gas source of hydrate in the basin is mainly the thermogenic hydrocarbon gas coming from the buried petroleum system. The activities of tectonic elements, such as faults and folders, were positively correlated with the enrichment of hydrate, and the hydrate occurrence was mainly related to the sand bodies of the delta plain in the Iperk, Kugmallit and Richards sequences. The permafrost above the hydrate stabilization zone plays a key role in the accumulation of gas hydrate.

     

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