牛庄洼陷岩性油藏含油气性及主控因素

渤海湾盆地牛庄洼陷的砂体主要分布在洼陷的深凹带、深凹带与缓坡带之间、缓坡带及中央低隆起带,砂体分为水下冲积扇、深水浊积扇和前缘滑塌浊积扇3种类型。其中,水下冲积扇砂体的厚度大,物性好,含油气性好;深水浊积扇砂体的含油性次之;而滑塌浊积砂体的含油气性最差。控制砂体含油气性的主要因素包括砂体埋深、沉积相及砂体类型、构造环境、砂体自身物性和压力。因此,随着埋深的增加,砂体的储量和含油饱和度明显增高;压力增高,砂体的含油气性也明显增加;处于深凹带的砂体含油气性好于缓坡带砂体及中央低隆起带的砂体。

Oil/gas shows in lithologic reservoirs in Niuzhuang sag and their main controlling factors

Sandbodies in Niuzhuang sag are mainly distributed in deep sag, area between deep sag and gentle slope zone,as well as central low upwarped area. They can be divided into 3 types, i.e. subaqueous alluvial fan, deep water turbidity fan, and frontal slump turbidity fan, of which the subaqueous alluvial fan sandbodies are thick and have good poroperm characteristics and oil/gas shows, while the oil/gas shows in deep water turbidity fan sandbodies are poorer, and that in slump turbidity fan sandbodies are the poorest. The main factors that control oil/gas shows in sandbodies are burial depth, sedimentary facies and types of sandbodies, as well as structural setting, poroperm characteristics and pressure of sandbodies. Reserves and oil saturation in sandbodies would significantly be heightened along with the increasing burial depth. The better the sandbodies' poroperm characteristics are, the better the oil/gas shows would be. They would also be significantly improved with increasing pressures. They are good in the deep sag, and become poorer towards the gentle slope zone, and become the poorest in the central low upwarped zone.