辽东湾海域古近系辫状河三角洲砂体沉积特征

Sedimentary characteristics of sand bodies in the braided river delta of Paleogene in Liaodong Bay

为研究辽东湾海域古近系辫状河三角洲前缘砂体沉积特征及主控因素,开展了薄片鉴定、岩心观察、测井分析等研究,并结合钻井情况对各类辫状河三角洲沉积模式及其差异性进行了综合分析。结果表明:(1)研究区古近系辫状河三角洲类型主要包括进积型和复合型2种类型;(2)古物源、古地貌和古气候3个因素共同控制了辫状河三角洲的类型及沉积特征,其中古物源供给强度是物质基础,控制了砂体的粒度及规模,古地貌中古沟谷控制了砂体的沉积位置,古气候和古地貌坡度陡缓影响了砂体的展布形态;(3)古物源强,与古沟谷对接好,古地貌平缓的沉积区域砂体厚度大、范围广,为油气勘探的有利目标。该研究成果可为辫状河三角洲储层的油气勘探开发提供借鉴作用。

To study the sedimentary characteristics and main controlling factors of the sand body in front of the Paleogene braided river delta in Liaodong Bay,it was carried out studies on thin-section identification,core observation,logging analysis,etc.And the sedimentary patterns of the braided river deltas and their differences were comprehensively analyzed in combination with the drilling conditions.The results show that:1)The types of Paleogene braided river deltas in the study area mainly include two types:progradation and composite.2)The types and sedimentary characteristics of the braided river delta are controlled by three factors:ancient provenance,ancient landform,and ancient climate.The supply intensity of ancient provenance is the material basis,which controls the grain size and scale of the sand body.The ancient gullies in the ancient landform control the sedimentary position of the sand body.The steep slope of the ancient climate and ancient landform affects the distribution form of the sand body.3)The sedimentary area with a strong ancient material source,good connection with ancient gullies,and gentle ancient landform has a large sand body thickness and wide range,which is a favorable target for oil and gas exploration.The research results can provide a reference for hydrocarbon exploration and development of the braided river delta reservoirs.