尼日尔Agadem区块油气成藏模式的认识

Understanding for hydrocarbon accumulation mode in Agadem Block,Niger

位于Termit盆地的尼日尔Agadem区块是中石油海外最具潜力的风险探区,为在深层次的研究上有更大的突破,从烃源岩特征入手,开展了Agadem区块白垩系上统Yogou组和Donga组成藏条件研究,重点分析油气运移特征、成藏条件及油气富集规律,并详细阐述了该区块的油气成藏模式。研究认为,白垩系上统的Yogou组和Donga组泥岩具有生烃潜力,Yogou组泥岩是Termit盆地的主力烃源岩。Yogou组砂岩储集层物性好,其上覆沼泽相泥岩可作为局部盖层;Donga组砂岩储集层物性次于Yogou组,以上覆Fachi泥岩为区域盖层。油气成藏的主控因素是区内发育的二级断层,Yogou组油气藏不仅为自生自储型油气藏,也受岩性控制,多为构造-岩性油气藏;Donga组油气藏处于下部成藏组合,主要是受构造控制以侧向运移为主的原生油气藏。

Agadem block is located in Termit Basin,Niger and is the most potential risk exploration area for CNPC overseas.To make a breakthrough in research,the authors started from the characteristics of hydrocarbon source rocks,studied the accumulation conditions for Yogou Formation and Donga Formation of Upper Cretaceous in Agadem block,analyzed characteristics of hydrocarbon migration,reservoiring conditions and oil-gas accumulation and distribution law,and elaborated the hydrocarbon accumulation mode for the block.Studies suggested that the mudstone in Yogou Formation and Donga Formation of Upper Cretaceous exist hydrocarbongenerating potential,the mudstone of Yogou Formation is major source rocks in Termit Basin and the physical property of sandstone reservoirs in Yogou Formation is good.Its overlying swamp mudstone may be the local capping bed and the physical property of sandstone reservoir in Donga Formation is inferior to that of Yogou Formation,the overlying Fachi mudstone is its regional caprock.The main control factor of hydrocarbon accumulation is second-order fault that is developed in Agadem Block.Yogou Formation is a kind of hydrocarbon reservoir for self-generation and self-storage reservoir,also controlled by lithology,and the dominant structure lithology reservoir.Oil-gas reservoirs in Donga Formation are in the lower part of oil-gas reservoir forming assemblage,which are mainly primary reservoirs in lateral migration and controlled by structures.