琼东南盆地盆底平原区天然气水合物成矿条件及成藏模式

Mineralization conditions and accumulation pattern of the gas hydrate in Qiongdongnan basin floor plain

利用地球物理、地球化学和钻井资料,在层序地层学的指导下,通过“源-渠-汇”耦合分析、地震属性雕刻和变温压场定量模拟等方法,对琼东南盆地盆底平原H区的天然气水合物成矿条件和成藏模式开展了系统研究。结果表明,H区广泛分布第四纪发育的多期浊积砂质沉积物,发育连通深部地层的底辟-气烟囱-微裂隙,具有满足水合物形成的温压条件,可形成深部成熟烃源与浅层未成熟烃源同时供烃、气烟囱-微裂隙垂向运移以及第四系海底扇与浊积水道砂富集的天然气水合物成藏模式,具有“深层气-浅层气-天然气水合物”叠覆成藏特征和“三气合采”地质条件,资源潜力大,是琼东南盆地天然气水合物勘探的有利靶区。

Based on geophysical,geochemical and drilling data,systematic research on mineralization conditions and accumulation pattern of the gas hydrate in the basin floor plain H area in Qiongdongnan basin,has been conducted by the guidance of the sequence stratigraphy and the methods of coupling analysis on“source-transportation-sink”,seismic attribute sculture and quantitative simulation on variable temperature-pressure field,etc.The results demonstrate that the following favorable conditions for the accumulation patterns of gas hydrates in the H area;namely,multi-phase Quaternary sandy turbidite sediments,the occurrence of diapir-gas chimney-microfissures that connect with deep formations,temperature-pressure conditions favorable for gas hydrate formation.The accumulation pattern of gas hydrate in the H area is coexisting hydrocarbon generation from deep mature source rocks and shallow immature source rocks,vertical migration along gas chimney and microfissures,and hydrocarbon accumulation in Quaternary submarine fan and channel turbidite sandstone.The accumulation character is the superimposition of“deep gas-shallow gas-gas hydrate”.The gas reservoir has the geologic condition of“three gas combined mining”with huge resource potential,and becomes a favorable target for gas hydrate exploration in Qiongdongnan basin.