惠民断陷湖盆演化过程与油气生成

古近系沙河衡组是惠民凹陷最重要的生油层系，该凹陷主要由临南、滋镇、阳信、里则镇等次级洼陷组成。由于沉积过程的差异性，导致形成了各洼陷不同的生烃环境和生烃潜力。其中临南洼陷沉积厚度大，而且有利干烃源岩发育的沙四段和沙三段沉积厚度也较大，属于持续沉降一深埋藏型洼陷，在其周围形成了大规模的油气聚集。而阳信、滋镇和里则镇虽然也发育了一定厚度的沙四段和沙三段泥质岩沉积，但由于后期沉降逐渐减慢，整个地层埋藏较浅，生烃怍用缓慢，在这些洼陷周围仅零里发现有低成熟或未成熟油气，该类洼陷属干逐渐抬升一中、浅埋藏型。由于临南洼陷充填演化的阶段性和多旋回性，形成了多套富含有机质的烃源岩层。油源对比表明，目前发现的原油均来自沙三段烃源岩，而富含有机质的沙四上亚段烃源岩虽然埋藏较深、成熟度较高，但是目前尚未发现来自该源岩的油气藏。因此，沙四上烃源岩应成为今后油气勘探的一个重要方向。

Evolution of Faulted Lacustrine Basin and Hydrocarbon Accumulation in Huimin Sag

Shahejie formation of Paleogene is the most important source rock in Huimin sag which is divided into sub-sags of Linnan,Zizheng,Yangxin,Lizezheng.The differences of these sags' depositions lead to their different environments and potentials for hydrocarbon generation.Linnan sub-sag is in big thickness of deposition,which is favorable for source rock evolution such as Sha-3 and Sha-4 sections,belonging to stable subsiding or deep buried type,around which there exist large scale hydrocarbon accumulations;while Xinyang,Zizheng and Lizezheng are in relatively shallow buried depth due to late slowing subsiding of pelitic rock deposits in certain depth of Sha-3 and Sha-4 sections,belonging to gradually rising and mid-shallow buried type,and their slower hydrocarbon-generation evolutions allow scattered low mature or immature hydrocarbons to be found around them.It is the episodic and multi-cycle features of sedimentation and evolution in Linnan sub-sag that form multi-set source rocks with rich organic matters.The correlation among the oil sources shows that producing crude oil just comes from Sha-3 source rock.The upper section of Sha-4 source rock is in deep buried depth and high maturity,but related oil-gas reservoirs are not found up to now.Hence,the upper section of Sha-4 source rock should be as an important target for petroleum exploration in future here.