双检数据上下行波场分离技术研究进展

随着海洋油气勘探开发技术的发展，水、陆双检海底接收的应用日趋广泛，上下行波场分离作为双检数据处理的关键技术，决定了资料处理品质及应用效果。在双检数据上下行波场分离技术的发展过程中，国内外学者提出了许多切实可行的技术方案。本文通过系统调研国内外相关文献，对上下行波场分离方法和技术进行了归纳和总结。首先基于波动理论，把双检数据与上下行波场联系起来，建立了双检数据标定和上下行波场分离的理论基础：水、陆检数据接收的波场分别为压力波场和质点垂直速度波场，可以分解为上行压力波场和下行压力波场及上行质点垂直速度波场和下行质点垂直速度波场；下行压力波场与下行质点速度波场振幅成正比，且极性相同，上行压力波场与上行质点速度波场振幅成正比，且极性相反。然后针对海底电缆/海底节点（OBC/OBN）水、陆检数据，建立了基于消除海水鸣震的双检数据处理技术。最后，总结出7种双检数据上下行波分离方法，包括：常数标定因子分离、频率—波数域分离、镜像分离、去虚反射分离、最优去虚反射分离、检波器脉冲响应分离和τ-p域分离等方法。双检数据上下行波场分离之前，首先要进行检波器脉冲响应校正；然后进行双检数据匹配和标定处理等，使水检数据中上下行压力波场与陆检数据中上下行质点垂直速度波场振幅和频率趋于一致，且由于下行压力和质点垂直速度波场极性相同、上行压力和质点垂直速度波场极性相反，陷波问题得到补偿，检波点端虚反射得到合理压制；最后实现最佳的上下行波场分离处理。

Research progress of up-going and down-going wavefield separation for dual-sensor data

With offshore oil and gas exploration and development, the application of dual-sensor ocean bottom receivers is becoming increasingly extensive. As the key technology of dual-sensor data processing, the up-going and down-going wavefield separation determines the data processing quality and application effect. In the development of the up-going and down-going wavefield separation techniques for the dual-sensor data, many feasible schemes have been proposed by scholars in China and other countries. In this paper, the methods and techniques of separating up-going and down-going wavefields are summarized by the systematic investigation of relevant literature. Firstly, in light of the wave equation theory, the dual-sensor data is linked with the up-going and down-going wavefields, which lays the theoretical foundation for the dual-sensor data calibration and the up-going and down-going wavefield separation. Specifically, the wavefield data received by hydrophone and geophone are pressure wavefields and particle vertical velocity wavefields respectively. The pressure wavefields can be decomposed into the up-going and down-going pressure wavefields, and the particle vertical velocity wavefields can be decomposed into the up-going and down-going particle vertical velocity wavefields. The amplitude of down-going pressure wavefields is proportional to that of the down-going particle velocity wavefields, and they have the same polarity, while the amplitude of the up-going pressure wavefields is proportional to that of the up-going particle velocity wavefields, and they have opposite polarity. Then, the OBC dual-sensor data processing technology based on eliminating the sea-water reverberations is established for OBC/OBN hydrophone and geophone data. Finally, this paper summarizes seven kinds of the up-going and down-going wavefield separation methods for dual-sensor data, including constant calibration factor separation, frequency-wavenumber domain separation, mirror separa-tion, deghosting separation, optimal deghosting separation, geophone pulse response separation and τ-p domain separation. Before the up-going and down-going wavefield separation for the dual-sensor data, the geophone impulse response correction should be carried out first. Then, various preprocesses are performed for the dual-sensor data, such as matching and calibration processes, so that the up-going and down-going pressure wavefields in the hydrophone data converge with the up-going and down-going particle vertical velocity wavefields in the geophone data in terms of amplitudes and frequencies. In addition, because the polarity of the down-going pressure wavefields is the same with that of the down-going particle vertical velocity wavefields, and the polarity of the up-going pressure wavefields is opposite to that of the up-going particle vertical velocity wavefields, the band notches are compensated, and the ghosts at the receiver point are reasonably suppressed. Finally, the best up-going and down-going wavefield separation is achieved.