青南洼陷构造特征及对油气成藏的控制作用

Structural features of Qingnan subsag and control factors on hydrocarbon accumulation

基于青南洼陷构造解释成果,对断裂系统发育情况、断裂演化及构造样式进行分析,并研究其构造特征对烃源岩的演化、储层发育及油气成藏的控制作用。结果表明:青南洼陷的形成开始于孔店组沉积时期,受东营凹陷拉张断陷机制及郯庐断裂带拉张—走滑机制的共同作用,发育NW,EW和NNE向的多期断层,形成伸展构造样式、伸展—走滑构造样式和走滑构造样式共3种不同的构造样式,伸展、走滑作用在不同演化阶段的叠加共同控制了青南洼陷的构造演化,导致其构造的特殊性与复杂性。构造演化控制了烃源岩的演化及储、盖层的发育,青南洼陷沙四段发育优质的烃源岩,广泛分布的滨浅湖滩坝砂成为青南洼陷油气成藏的主力储层,形成以岩性-构造和构造-岩性为主要类型的沙四段滩坝砂岩油藏。

Based on the structural interpretation and fault system of Qingnan subsag,the fault evolution and tectonic styleswere analyzed in detail. The effects on hydrocarbon source rock evolution,reservoir development and controls on hydrocar-bon accumulation were studied. The results show that Qingnan subsag began to build up during the sedimentation of Kong-dian Formation while multi-phase faults with directions of NW,EW and NNE developed due to the interaction of stretch ofthe Dongying sag and the strike-slip mechanism of TanLu faults. As a result the extensional tectonic style,the extensionaltectonic-strike-slip style and strike-slip style developed in different evolutional stages and controlled the tectonic evolu-tion,thus bring on its specification and complication. The tectonic evolution controls the evolution of hydrocarbon sourcerocks and the development of reservoirs and cap rock. Excellent source rock of Es4 developed in Qingnan subsag;the litto-ral and shallow lake bars developed widely in Qingnan subsag are the main oil and gas entrapment to form bar and shoalreservoirs in Es4 that are mainly tectonic and tectonic-lithology type.