深水沉积体系内部结构的地震沉积学研究

尼日尔深海盆地处于被动大陆边缘,其深水沉积体系中的深切谷、峡谷和水道等异地沉积体主要由砂砾岩组成,并夹于原地沉积作用形成的半深海-深海亚相暗色泥岩、泥灰岩中,能构成良好的生储盖组合关系,是油气勘探的主要目标。由于深水盆地钻井较为稀少,为了准确研究深水沉积体系,采用了地震沉积学的理论和技术手段。异地沉积体具有独特的地震响应特征——强振幅、较低频率、"U"字外形等,能通过三维地震资料进行识别与研究,并对其内部结构进行精细的描述与刻画。通过地震相分析,从尼日尔深海盆地三维地震剖面上识别出具有"U"字外形的水道,结合地震振幅属性分析,清晰地刻画出了目的层古水道展布。

Study on deep-water sedimentary system internal structure by seismic sedimentology

Niger deep-sea Basin lies in the passive continental margin,its deep-water allogene sedimentary system such as deep valley,canyon and channel was mainly made up of glutinite,with hemipelagic-deep-sea intrafacies mudstone and limestone formed by autochthonous deposit embedded.Therefore,source-reservoir-cap combination relationship is generated and became the main target of the deep-water oil and gas exploration.As a result of sparse deep-water drilling,for accurate study on deep-water depositional system,we mainly rely on the theory and technique of seismic sedimentology.Allogene deposit body has unique seismic response characteristics,such as high amplitude,low frequency and "U" shape,so we can identify and describe delicately its internal structure by studying 3D seismic data.Through the analysis of seismic phases,a "U" channel was recognized from the Niger deep-sea Basin seismic profile.Combined with the seismic amplitude property analysis,the ancient waterway distribution in target layer was clearly depicted.