摘要:
以油气藏形成的源储控制因素为核心和切入点,总结出珠江口盆地3种主要的油气运聚成藏机制,即古近系半地堑洼陷自源型油气成藏机制、三角洲砂岩—生物礁外源型油气成藏机制、深水扇系统外源型油气成藏机制。古近系半地堑洼陷自源型油气运聚成藏机制,其烃源供给系统与油气运聚系统均位于半地堑体系内部,具有自源型近距离原地运聚成藏的特点;三角洲砂岩—生物礁外源型油气成藏机制,其烃源供给主要来自三角洲—生物礁运聚成藏体系之外下伏的古近系半地堑烃源供给系统,因此,其纵向烃源断裂体系及构造脊砂体和不整合面构成的油气运聚系统为主要控制因素;处于盆地南部陆坡深水区的深水扇系统外源型油气运聚成藏机制,其烃源供给亦主要来自下伏的古近系地堑型烃源供给系统,且上渐新统海相烃源岩亦有贡献,而纵向烃源断裂体系与深水扇体系中良好储层共同构成的深水油气运聚系统,则是形成这种油气藏之关键所在。
Abstract:
Taking source and reservoir as the key points for oil and gas accumulation,there are three main mechanisms of oil and gas migration and accumulation in the Pearl River Mouth Basin.They are the hydrocarbon accumulation mechanism with autochthonous source from the half-graben-type depressions in Paleogene; the hydrocarbon accumulation mechanism in the deltaic sands-reef systems with allochthonus oil source; the hydrocarbon accumulation mechanism of deep-water fan system with oil and gas source from outside.For the first mechanism,both the oil and gas supply system and the migration and accumulation system occur within the Paleogene half-graben system,and characterized by autochthonous source and short distance of migration.For the second mechanism,delta sands-reef deposits are effective reservoirs,and oil and gas supply system and migration and accumulation system remain in the Paleogene half-graben system out of the delta sands-reef systems.Therefore,its main controlling factors are the migration systems including vertical crossing source fault system,the sandbodies on structural ridges and unconformities.The oil and gas supply system and migration and accumulation system of deep-water fan system are mainly located on the southern slope of deep water zone.Oil and gas are mainly from the half-graben system,even the marine source rocks in Oligocene may also contribute a little.The key factors to control oil and gas migration and accumulation are the vertical fault system crossing source rocks and the availability of good reservoir in the deep-water fan system.
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