【摘要】 南海北部陆坡区天然气水合物(以下简称水合物)资源潜力虽然巨大,但影响该区水合物成藏的地质因素却异常复杂。为此,从水合物成藏的稳定域、气体来源、气体疏导体系以及储集层特征等宏观地质条件的视角,剖析了水合物成藏的地质条件及主要控制因素。结果表明:1南海北部热流分布较复杂,影响着水合物稳定域的空间分布,而区域构造地质演化则控制着水合物成矿气体来源、气体疏导体系、富集空间及储层物性特征;2南海北部陆坡从西部—中部—东部,水合物成藏条件及控制因素具有明显的差异性,对水合物成藏模式和空间分布都产生了深刻影响;3总体而言,从陆坡的东段到西段新构造活动渐次减弱,水合物稳定域厚度由东而西、由南向北厚变薄,东部以台西南盆地深水斜坡带成藏条件最为优越,兼具扩散型和渗漏型水合物发育的地质条件,水合物矿藏在稳定域内呈多层、多形式富集的特点,中部以神狐海域白云凹陷南坡为典型代表,为扩散型水合物发育的有利区,水合物矿藏在稳定域底部呈单层发育特点,西南部以琼东南盆地的陆坡深水区成藏条件最为优越,有利于发育渗漏型水合物矿藏。更多还原

【Abstract】 Natural gas hydrate resources are thought to be extremely rich in the northern slope area of the South China Sea,where the geological conditions,however,were quite complex indeed for the hydrate formation.Therefore,from the viewpoints of regional geological settings such as stability condition,origin of source gas,gas migration and reservoir characteristics,we discussed the gas hydrate formation conditions and the associated controlling factors in this study area on the basis of recent years’ research achievements.As a result,we obtained the following findings.(1)The complexity of the heat-flow distribution in the northern South China Sea has a great impact on the special extension of hydrate stability domain,while the geological tectonic evolution in this area controls the hydrate origin,gas channel system,storage space,and reservoir petrophysical properties.(2)Three distinct types of gas hydrate reservoirs identified with different formation conditions and controlling factors are distributed along the western,middle and eastern parts in this study area respectively.(3)In general,from east to west in this slope area,new tectonic activities are decreasing gradually,while the thickness of gas hydrate stability zone is becoming thinner both from east to west and from south to north.In the eastern part,the typical gas hydrate occurrence is located in the deep water slope of Southwestern Taiwan Basin where gas hydrates are accumulated as both diffusive and seepage types in several sediment layers.In the middle part,the typical occurrence,which is mainly dominated by dispersed gas hydrates often in single sediment layer,is represented by the southern slope of the Baiyun Sag,Shenhu Area.In the western part,especially the deep water slope of the Qiongdongnan Basin provides favorable condition for the accumulation of seepage gas hydrates.更多还原