格陵兰岛西部巴芬湾天然气水合物流体运移系统

Gas hydrate migration system in Baffin Bay, Western Greenland

格陵兰岛西部巴芬湾发育丰富的油气藏和天然气水合物藏,其形成分布与流体运移系统密切相关。根据浅层地震数据,利用BSR识别、地震相分析、地温梯度和热流值异常方法,追踪流体运移路径,分析多边形断裂对水合物分布的控制作用,研究各地质构造形成的流体运移系统。结果表明:研究区发育两个天然气水合物稳定带(GHSZ),其热流值分布具有非均一性,多边形断裂发育处热流值高;流体特征表现为纵波反射模糊带、“亮点”地震相异常、“平点”地震相等;高密度多边形断裂为流体运移提供疏导通道,增加天然气水合物的储存空间;深部裂解气通过聚集型高通量流体运移通道(底辟或构造隆起、断裂、高渗透层等)在垂向和侧向上运移,在研究区北部形成天然气水合物藏。该结果对降低前沿盆地的天然气水合物开发风险具有指导意义。

Many hydrocarbon and gas hydrate reservoirs are found in Baffin Bay of Western Greenland,whose formation and distribution are closely related to fluid migration systems.Based on shallow seismic data,through BSR identification,seismic facies analysis,geothermal gradient and heat flow anomalies,we deals mainly with tracking fluid migration paths,analyzing the control effect of polygonal faults on hydrate distribution,and revealing the fluid migration system formed by terrestrial structures.The results show that:two gas hydrate stability zones(GHSZ)are recognized in the study area,whose heat flow value distribution is non-uniform,exhibiting high value in polygonal faults developed zones.The fluid characteristics on seismic profile of the study area are displayed as longitudinal wave reflection fuzzy zone,"bright spot"seismic facies anomaly,"flat point"seismic facies features and so on.High-density polygonal faults provide a channel for fluid migration and increase the storage space for hydrates.Deep gas migrates vertically and laterally through focused high-flux fluid migration channels(diapirs or uplifts,fractures,high permeability layers,etc.),and finally form gas hydrate reservoirs in the north of study area.This result is of great significance for reducing the risk of natural gas development in frontier basins.