辽中凹陷高精度层序地层格架划分与沉积相研究

针对辽中凹陷东营组碎屑岩地层进行了高精度层序地层划分,利用地震沉积学方法进行了沉积相研究,揭示了三角洲、浊积扇等沉积体系的分布规律及控制因素。结果表明,辽中凹陷东营组地层可划分为3套三级层序(Sqd1、Sqd2和Sqd3),在三级层序Sqd2内部识别出一套易于追踪的水退界面,以此水退界面将Sqd2层序划分为2套四级层序。结合测井响应特征,对地震剖面进行精细刻画,在两套四级层序中识别出三角洲、辫状河三角洲、浊积扇等沉积相,与三角洲伴生的浊积扇富泥,而与湖相泥质沉积伴生的浊积扇富砂。通过提取地震属性识别沉积体边界,了解了四级层序的沉积相平面展布规律,发现沉积体系展布受水系物源、古地形、相对湖平面变化及古气候控制。

Seismic sedimentary facies study based on high-resolution sequence framework: A case study on sequence Sqd2 in Liaozhong Depression

Regarding the Dongying clastic formation of Liaozhong Depression,high-resolution sequence and seismic sedimentary studies were utilized to describe sedimentary facies in order to disclose the distribution and controlling factors of the sedimentary system.The study results show that the strata of Dongying formation in Liaozhong Depression could be divided into three third-order sequences(Sqd1,Sqd2 and Sqd3).Two four-order sequences in the sequence Sqd2 could be identified by tracing a set of regressive boundaries.Based on seismic interpretation combined with logging characteristics,the seismic facies of delta,braided delta,turbidite fan were identified.Turbidite fan accompanying delta was rich in mud,while accompanying lacustrine turbidite fan was rich in sand.The boundary of sedimentary deposit could be identified by extracting seismic attribute.Distribution of sedimentary facies of fourth-order sequences could also be dominated by water system,ancient landform,relative lake level change and palaeoclimate.