沅江东次凹古近系桃源组—汉寿组沉积体系与层序地层研究

【作者】 游李伟；

【导师】 彭军；

【作者基本信息】 西南石油大学 ， 矿产普查与勘探， 2006， 硕士

【摘要】 由于缺乏系统的沉积与层序地层研究，这在很大程度上制约了沅江凹陷油气勘探的总体规划和部署。本文运用沉积学和层序地层学原理，利用钻井、测井、地震等多种资料对沅江东次凹古近系桃源组—汉寿组地层进行了层序地层与沉积体系的综合分析。根据沉积相识别标志，选取具有典型特征的井段建立岩—电—相转换模型，对研究区内的24口井进行了单井沉积相解释，从中识别出湖泊、三角洲、扇三角洲、冲积扇以及河流5种沉积相，并细分为12种亚相。根据地震反射终端类型的不同，可将古近系地层分为2个地震层序和6个地震亚层序，并对各地震亚层序进行了地震相分析。在沉积相和地震层序研究的基础上，将古近系桃源组～汉寿组地层划分为7个层序及16个体系域。其中，SQ1和SQ4层序底界面为Ⅰ型层序界面，发育低位体系域、湖侵体系域和高位体系域；SQ2、SQ3、SQ5、SQ6和SQ7层序底界面均为Ⅱ型层序界面，只发育湖侵体系域和高位体系域，不发育低位体系域。以体系域为单位，分析了古近系SQ1～SQ7层序各体系域内部沉积体系组合及演化特征，以及地层厚度变化和砂体分布特征。通过以上分析，得出控制沅江东次凹古近系层序发育的主要因素是构造运动和气候。更多还原

【Abstract】 The projections and deployments of petroleum exploration in Yuanjiang sag are restricted by lacking of research on sequence stratigraphy and depositional system. This paper is a comprehensive research on sequence stratigraphy and depositional system of Taoyuan-Hanshou formations in East-Yanjiang subsag based on the principle of sedimetology and sequence stratigraphy, taking use of the materials of well drilling, logging and seismic survey. According to the identification marks of sedimentary facies, having established rock-logging-facies transformation model from the typical interval, the facies are defined in each of the 24 wells in this area, they are 5 kinds of facies in total, including: lacustrine, delta, fan- delta, alluvial fan and fluvial facies, and 12 kinds of micro-facies. In terms of the different forms of the seismic wave reflection terminal, The Paleogene stratum in East-Yanjiang subsag is divided into 2 seismic sequences or 6 seismic subsequences, and the seismic facies is analyzed in seismic subsequences. On the base of research on sedimentary facies and seismic sequence, the Taoyuan-Hanshou formations in paleogene are divided into 7 sequences and 16 systems tracts. The bottom boundary of SQ1 and SQ4 sequence each which consists of lowstand systems tract, transgressive systems tract and highstand systems tract is I-type sequence boundary; and the bottom boundary of SQ2, SQ3, SQ4, SQ5, SQ6 and SQ7 sequence each which consists of transgressive systems tract and highstand systems tract is II-type sequence boundary. The characteristics of combination and evolution of depositional systems, variety of strata, and distribution of sandbodies are analyzed in each systems tract. Fanally, it is known that the main controlling factors of sequence development are tectonic movement and climate change.更多还原