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由于地质构造复杂,表层结构变化剧烈,羌塘盆地一直未能获得令人满意的高信噪比二维地震资料.因此,采用可控震源和井炮激发在北羌塘凹陷与中央隆起带之间的托纳木—笙根地区开展了420 km的高密度高覆盖宽线地震采集试验.可控震源激发参数:振动台次3台1次、扫描频率6~84 Hz、驱动幅度70%、扫描长度18 s.井炮激发参数:单井高速层下7 m激发,最浅井深18 m,药量18 kg;组合方式激发为2口井×15 m×12 kg或3口井×12 m×8 kg.2串检波器沿测线线性图形为最佳接收因素.井炮激发的覆盖次数介于360~960次之间,观测系统为4L3S、3L3S和2S3L;可控震源激发的覆盖次数介于960~1920次之间,观测系统为4L3S、3L3S和2S3L;炮间距介于30~120 m之间.试验结果:(1)采用井炮和可控震源激发的“高密度-高覆盖-宽线”采集技术,首次在羌塘盆地托纳木—笙根地区获得了一批质量优良的、可用于地质构造解释的地震剖面;(2)尽管可控震源单炮记录无法与井炮相比,但其高密度高覆盖采集技术能获得质量优于或等同于井炮的地震资料;(3)羌塘盆地托纳木—笙根地区适合于采用可控震源和井炮联合的宽线采集方案,可控震源覆盖次数1000次左右,井炮覆盖次数360次左右,观测系统3S3L或者2S3L即可.
Due to the complicated geological structure and the drastic changes in the surface structure, the Qiangtang Basin has not been able to obtain satisfactory high-SNR 2D seismic data. Therefore, using vibroseis and well gun excitation in the northern Qiangtang depression and the central uplift 420 km high-density high-coverage wide-line seismic acquisition was carried out in the Tonaki-Shenggen area between China and the United States.Vibrator excitation parameters: the first three times of shaking table, the scanning frequency of 6 ~ 84 Hz, the driving amplitude of 70% The scanning length was 18s. Excitation parameters of well guns: Excitation at 7 m under single-well high-velocity layer, the deepest well 18 m and the dose of 18 kg; the combination mode was excited to 2 wells × 15 m × 12 kg or 3 wells × 12 m × 8 kg.2 string geophones along the linear pattern of the line as the best receiving factor.The well gun firing coverage between 360 ~ 960 times, the observation system for the 4L3S, 3L3S and 2S3L; Vibrator excitation coverage Between 960 and 1920 times, the observing systems are 4L3S, 3L3S and 2S3L, and the distance between the shots is between 30 and 120 m.Results: (1) The high density-high Covering - wide line "acquisition technology, for the first time in the Qiangtang Basin Nathan - Shenggen region received a number of excellent quality, can be used for geological formations (2) Although the single-shot record of vibroseis can not be compared with well gun, the high-density and high-coverage acquisition technology can obtain seismic data of better quality or equivalent to that of well gun; (3) The Namu-Shenggen region is suitable for the wide-line acquisition scheme using the joint of vibroseis and the well gun. The number of vibrator covers is about 1000 times, and the coverage of the gun is about 360 times. The observation system 3S3L or 2S3L can be used.