【摘要】 CSDP-2井为南黄海盆地中部隆起第一口以探查南黄海海相地层属性的科学钻探井,为了建立地震层位与钻井地层界面两者准确的对应关系,实施了垂直地震剖面(VSP)测井.针对浅部存在速度突变界面对地震波能量屏蔽作用严重的难题,根据大容量气枪激发的地震信号主频低、穿透能力强的优势,采用了4支容量为1500 in~3的Bolt气枪,组合设计形成总容量6000 in~3的气枪阵列,作为VSP资料采集的地震激发震源.在较小的井源距条件下,解决了海相地层顶部高速屏蔽层对地震波的强烈阻滞问题,获得了井孔内高信噪比的纵波波场信号特征,并得到了高速屏蔽层之下的有效转换波信号,为地震层位与钻井地层的关系建立、地层弹性波速度提取提供了良好的数据基础,而且为推广VSP观测与大容量气枪联合应用提供了经验与借鉴.更多还原

【Abstract】 CSDP-2 well is the first scientific drilling well in the central uplift of the South Yellow Sea Basin to explore the marine stratigraphic attributes of the South Yellow Sea. In order to establish an accurate correspondence between seismic horizon and drilling formation interface, Vertical Seismic Profile(VSP) logging has been implemented. In order to establish an accurate correspondence between seismic horizon and drilling formation interface, Vertical Seismic Profile(VSP) logging has been implemented. Aiming at the serious problem of shielding seismic wave energy by velocity sudden change interface in shallow region, according to the advantages of low main frequency and strong penetration ability of seismic signal excited by large capacity air gun, 4 Bolt air guns with a capacity of 1500 in~3 were used to design and form a total capacity of 6000 in~3 air gun array, which was used as seismic excitation source for VSP data acquisition. Under the condition of small well source distance, the problem of strong seismic wave retardation caused by high-speed shielding layer on the top of marine strata is solved, the characteristics of P-wave field signal with high signal-to-noise ratio in borehole are obtained, and the effective converted wave signal under high-speed shielding layer is obtained, which provides a good data basis for establishing the relationship between seismic horizon and drilling stratum and extracting formation elastic wave velocity, and also provides experience and reference for popularizing the joint application of VSP observation and large-capacity air gun.更多还原