汤原断陷构造沉积特征与油气成藏分布规律

汤原断陷是发育在前中生界基底之上受依兰—舒兰地堑东、西2条北北东向大断裂控制且被北西向断裂所切割的中新生代断陷盆地,具有东西分带、南北分块的盆地格架。发育扇三角洲—湖泊沉积体系,形成了白垩系和下第三系2个相对独立的构造和成藏单元。研究表明:汤原断陷经历了早期中生代断陷期、新生代断陷发育期和断陷后期3个发展阶段,最大沉积厚度达6 000 m,下第三系和白垩系是主要勘探目的层。受白垩纪末期燕山运动和新生代后期运动的影响,原形盆地遭受了强烈改造,原来的构造格局和地层沉积格架发生了显著变化,油气藏遭受了很大破坏,圈闭变得复杂。断裂和岩性对该区油气藏的形成起主要控制作用。进行三维地震勘探,在凹陷或斜坡区寻找非构造圈闭有利区带,同时,加强对白垩系地层油气勘探,寻找保存完好的古构造是近期该断陷油气勘探的主要目标。 

STRUCTURAL-DEPOSITIONAL FEATURE AND OIL-GAS RESERVOIR DISTRIBUTION IN THE TANGYUAN FAULT DEPRESSION

Developed on Premesozoic basement,the Tangyuan Fault Depression is a Mesozoic and Cenozoic Fault Depression.Basin controlled by two large faults toward NNE,cut by faults toward NW with divided zones between east and west and fault blocks between south and north.It exited Cretaceous and Paleogene two relatively dependent structure and oil-gas unit with fan delta-lake depositional system.The results illustrated that the Tangyuan Fault Depression went through three stages: early fault depression in Mesozoic,developing fault depression and late fault depression in Cenozoic.Its feature is giant sedimentary thickness,maximum 6 000 metres.Cretaceous and Paleogene are formation of interest.As a result of Yanshan event at the end of Cretaceous and Himalayas event at the late Cenozoic,prototype basin is subjected to strong deformation;prototectonics and sedimentary frames were obviously changed;oil-gas reservoirs were destroyed.Oil-gas reservoirs are principally controlled by faults and lithology.