【摘要】 利用大陆科学钻探取得的岩芯岩性、构造编录和波速、中子密度测井资料,可以比较准确地标定大陆科学钻探主孔两侧三维地震发现的反射体.二维地震剖面上的反射体可能与二维测线方向有关,三维地震提供了与方向无关的反射体信号,为结晶岩区地壳反射波的标定提供了更加准确可信的基础数据.只有在建立准确的波速模型、由测井资料合成的地震道与三维地震剖面之间达到完美拟合之后,反射体标定才有意义.地震剖面、测井和岩芯资料的柱状对比图由于未考虑非线性时深转换和钻孔的弯曲,只能供初步分析用;反射体的详细标定还要考虑到时深转换的非线性及钻孔的弯曲,逐一制作标定分解图.引起结晶岩中反射体的机制是多方面的,文中逐一分析了过主孔的10个主要地震反射体的特点及成因,总结了结晶岩地区反射体分为三大类:(Ⅰ)与韧性剪切作用有关的反射体;(Ⅱ)与侵入岩或正变质岩岩体有关的反射体;(Ⅲ)与围岩岩性构造不均匀性有关的反射体.更多还原

【Abstract】 Three-dimensional seismic survey has been carried out for the Chinese Continental Scientific Drilling(CCSD) project,showing that many reflectors occurr in the upper crust beneath the drilling area.Calibration of the reflectors by using cores and well-logging data can significantly enhance reliability of their interpretation.As 2-D seismic reflectors might be related to direction of the 2-D lines,3-D surveys present reflectors unrelated to the line direction,therefore provide more reliable reflectors for the calibration.Only after obtaining a correct velocity model that gives perfect fit between the 3-D seismic profile and the synthetic seismic trace derived from well-logging data,the calibration of reflectors can become meaningful.Simple comparison of the core log,well-logging curves and reflection sections is not enough for the calibration,because non-linear time-depth conversion and deviation of the well are not considered in the procedure.The calibration should proceed from one reflector to another considering both the non-linear time-depth conversion and deviation of the well.The calibration at the CCSD site via the main hole finds many causes that can generate reflectors in the crystallized crust.They include mainly three types as follows:(a) ductile-shearing-origin reflectors;(b) intrusion-or-metamorphic-lens origin;and(c) origins related to inhomogeneity of country rocks,such as gneisses.更多还原