渤海莱州湾凹陷深洼带垦利10-2新近系大型油田发现与意义

莱州湾凹陷是渤海海域重要的富烃凹陷,但其深洼带浅层一不生烃、二无油源断层、三无汇烃构造,是传统地质认识中的“勘探禁区”。近年来,随着对渤海浅层油气成藏条件及主控因素认识的深入,尤其是油气运移“汇聚脊”控藏认识的提出,为深洼带新近系找油提供了新的视角,并在此认识指导下开展了莱州湾凹陷深洼带石油地质条件再分析与成藏规律攻关研究。创新提出了基于陡坡砂体型汇聚脊控制的浅层规模性岩性砂体“迂回式”成藏模式,为寻找深洼带浅层有利勘探目标指明了方向;形成了砂体整体解剖技术,实现了浅层多期大型连片复合型砂体的精细刻画,为新近系规模性油气成藏寻找到有效储集空间。2021年,在莱州湾凹陷深洼带新近系成功发现并高效评价了垦利10-2亿吨级岩性油田,不仅在渤海深洼带发现了首个亿吨级岩性油田,更为类似盆地的凹陷区浅层勘探开辟了新领域。

Discovery and significance of KL10-2 Neogene large oilfield in deep subsag zone of Laizhouwan sag,Bohai sea

The Laizhouwan sag is an important hydrocarbon-rich sag in Bohai sea,but its shallow strata in the deep subsag zone has no hydrocarbon source rock,no oil source fault and no hydrocarbon accumulation structure.In traditional sense,it is regarded as an“exploration-forbidden zone”in geological understanding.In recent years,with the deepening of understanding on the origin and main controlling factors of shallow oil and gas reservoir in Bohai Sea,especially the introduction of new conception of“accumulation ridge”that controls oil and gas migration and accumulation,provides a new perspective for exploration of Neogene oil in deep subsag zone.Inspired by this envision,the oil accumulation geological condition and hydrocarbon accumulation law in the deep subsag zone of Laizhouwan sag are further studied.A“meandering”hydrocarbon accumulation model of shallow large-scale lithologic sand body controlled by the accumulation ridge of steep slope sand body is innovatively put forward in this paper,which points out the direction for exploration of Neogene oil in deep subsag zone;Based on that,a set of complete sandbody anatomy technology is developed,which is applied to realize the fine characterization of shallow multi-stage large-scale continuous composite sandsbody,thus finding the large-scale effective reservoir spaces of Neogene oil and gas.In 2021,the discovery of 100 million ton KL10-2 Neogene oilfield in the deep subsag zone of Laizhouwan sag Bohai Sea is a successful breakthrough.After efficient evaluation,it is considered that this oilfield is not only the first 100 million ton lithologic oilfield discovered in the Bohai Sea deep subsag zone,but also opens up a new field for shallow oil and gas exploration in the sag zones of similar basins.