青海NMH工区谐波干扰特征及压制技术研究

青海NMH工区地表复杂,近地表岩石硬度差异大,有必要开展不同地表耦合条件下可控震源谐波干扰的分布特征研究和压制方法试验。通过理论计算和对实际资料的统计分析,总结了谐波干扰变化规律,确立了相应的谐波干扰压制方法。研究结果表明,可控震源与地表耦合产生的谐波干扰与地表岩石硬度密切相关,一般随地表岩石硬度增加,谐波干扰强度显著增强,但相位畸变相应减小。通过优选激发点位置、有针对性地改善地表耦合条件、合理调节相位控制增益,甚至研究和采用诸如新型震源平板等多种技术措施,尽可能保证在硬度值约40(即接近“半刚度”)的地层中激发,可以最大限度降低谐波干扰的影响,提高地震资料的品质。理想情况下,可使得谐波干扰能量降低约30%,单炮地震记录信噪比提高约260%。

The hardness of the near-surface rock in NMH area in Qinghai Province varies largely,it is necessary to research on the distribution characteristics of harmonic interference and the experiment on its suppression techniques under different surface coupling conditions.By theoretic calculation and statistical analysis of real data,we concluded the variation rule of harmonic interference and established the corresponding suppression method for harmonic interference.The results indicate that the harmonic interference generated by the coupling of vibroseis and surface is closely related with the hardness of surface rock.Generally,the strength of harmonic interference is obviously enhanced and the phase distortion is decreased along with the increase of surface rock hardness.We carried out some measurements to keep shooting in the formations with hardness at about 40 (close to “semi-rigidity”),such as optimizing shooting position,improving surface coupling conditions,reasonably adjusting phase controlling gain,even adopting new source plane,thus the impact of harmonic interference is eventually eliminated to maximum and the quality of seismic data is improved.Ideally,the energy of harmonic interference can be decreased about 30% and the signal-to-noise ratio of single shot record enhanced about 260%.

国家科技重大专项(2011ZX05006-002)和国家高技术研究发展计划(863计划)项目(2011AA060300)共同资助。