基隆凹陷古-中新世沉积相分析

Sedimentary Facies Analysis from Paleocene to Miocene in Keelung Sag

基隆凹陷是东海陆架盆地南部重要的含油气凹陷,其在新生代经历了古-始新世快速裂陷,渐新世裂后沉降,中新世区域沉降三个演化阶段。为了更有效地评价其油气资源潜力,需要对其古-中新世沉积相进行研究。可以用地震相和振幅属性相结合的方法分析基隆凹陷沉积相特征。总体上,新生代期间基隆凹陷以滨浅海为沉积背景,在凹陷西侧发育陆架砂、三角洲、斜坡扇等沉积体系,中部洼槽带发育浊积砂。基隆凹陷古-始新统浅海相泥岩为最有利的烃源岩,古近系凹陷西部发育的陆架砂、三角洲分支河道砂、斜坡扇和中央洼槽带发育的浊积砂,能形成有利储层,中新统广布的厚层浅海相泥岩可作为全区稳定分布的区域盖层。

Keelung Sag is an important oil and gas sag in the southern part of East China Sea shelf basin.The evolutional stages of Cenozoic tectonic in Keelung Sag are divided into faulted period in Paleocene and Eocene,post-rift subsidence period in Oligocene and regional subsidence in Miocene.In order to evaluate its oil and gas resource potential more effectively,it is necessary to study the sedimentary facies for the formation of Paleocene to Miocene.The sedimentary facies characteristics of Keelung Sag can be analyzed by a combination of seismic facies and amplitude attributes.With the epicontinental sea sedimentary background,Keelung Sag accepts shelf sand,delta and slope fan sediments on the west side,in the central depression belt turbidite sand body is often scattered.The shallow Marine mudstone of the Paleocene and Eocene in Keelung Sag is the most favorable hydrocarbon source rock.Different kinds of sand bodies of Paleogene on the west side and in the central depression belt can form favorable reservoir.The thick shallow marine mudstone with wide distribution in Miocene can be a stable regional caprock.