涟源凹陷泥盆纪佘田桥组沉积与地震相特征

Sedimentary and Seismic Facies Response Characteristics of Devonian Shetianqiao Formation in Lianyuan Depression

涟源凹陷泥盆纪佘田桥组为台盆相间的海相沉积,盆地相为有利的页岩气富集区。目前对台盆相研究多依靠地质露头和少量测井资料,对台盆相地震相特征研究较少,从而制约着本区页岩气勘探进展。本文基于新采集的二维地震资料,从湘新地3井钻井岩心资料和测录井资料入手,通过对该井主要目的层的合成记录标定、目的层反射轴响应特征分析等工作,开展佘田桥组沉积相序划分及地震相特征分析。结果表明:泥盆纪佘田桥组台地相地震反射特征为不连续弱振幅杂乱-亚平行结构,盆地相地震反射特征为连续强振幅平行结构,并在此基础上利用地震相特征开展佘田桥组有利相区平面预测,明确了佘田桥组盆地相分布范围,为佘田桥组页岩气勘探提供部署依据。

Shetianqiao Formation of Devonian in Lianyuan Depression is a marine deposition altermated with platform and basin facies,which is favorable for shale gas acclumation.At present,the research on platform-basin facies mostly depends on field outcrops and limited wells.Few researches have been made on the characteristics of platform-basin facies,which restricts shale gas exploration in this area.Based on the newly acquired two-dimensional seismic data,the drill core and logging data of Well Xiangxindi-3 were analyzed.This paper carries out the division of sedimentary facies sequence and the analysis of seismic facies characteristics of Shetianqiao Formation through the calibration of synthetic records of the main target layers of the well and the analysis of the response characteristics of reflection axis of the target layers.Results indicate that the seismic reflection characteristics of platform-facies of Shetianqiao Formation in Devonian are characterised by discontinuous weak amplitude disorder-sub-parallel structure,while seismic reflection characteristics of basin facies are continuous strong amplitude parallel structure.On this basis,the plane prediction of favorable facies area of Shetianqiao Formation is discussed by using reflection character of seismic facies.The distribution of deposition facies of Shetianqiao Formation is defined,which could provide the basis for shale gas exploration of Shetianqiao Formation.