扫描频率激振下振动器-大地耦合振动与频宽拓展研究

可控震源是油气勘探的主力装备，对深层、超深层和非常规油气资源勘探起着重要作用。由于扫描频率激振下振动器激振精度和适用频宽不足，导致激发的勘探信号畸变、低频成分不足、高频出力失准，严重限制了可控震源的勘探能力。本项目通过构建平板底面压力分布方程，以动刚度动阻尼及参振土体描述振动器与大地之间的非线性互作用，建立扫描频率激振下振动器-大地耦合振动模型，突破模型适用频宽较窄的局限，揭示振动器-大地耦合振动规律；基于振动出力和下传能量分析，研究耦合系统参数对激振性能的影响规律，掌握关键耦合系统参数，提高激振精度；以提高振动出力、下传能量和频宽倍频程为目标，建立振动器频宽拓展多参数多目标优化模型，结合针对不同勘探需求的评价因素权重集研究，提出个性化振动器频宽拓展优化设计策略。研究成果为可控震源结构优化设计与个性化勘探提供理论支撑，对于提升激振精度、实现宽频激振，提高其勘探能力具有重要意义。

The vibroseis is the main equipment for oil and gas exploration, which plays an important role in the exploration of deep, ultra-deep and unconventional oil and gas resources. Due to the lack of excitation precision and applicable bandwidth of the vibrator under the excitation of sweep frequency, the exploration signal has the disadvantages of distortion, insufficient low-frequency contents and misalignment of ground force at high frequency, which seriously limit the exploration capability of the vibroseis. In this research, the vibrator-ground coupling vibration model under the excitation of sweep frequency will be established, based on constructing the pressure distribution equation of the baseplate bottom surface and proposing dynamic stiffness, dynamic damping and captured ground to describe the nonlinear interaction between the vibrator and the ground. The establishment of the model will break through the bandwidth limitation of the vibrator excitation model and reveal the vibrator-ground coupling vibration law. Based on the study of the ground force and the downgoing energy, the influence law of coupling system parameters on excitation performance will be investigated, the key parameters of coupling system will be obtained, and the excitation accuracy will be improved. With the goal of improving the ground force, the downgoing energy and the octave of bandwidth, the optimization model of vibrator bandwidth extension with multiple parameters and multiple objectives will be established. With the study of weight coefficients for different exploration needs, the optimization design strategy of personalized vibrator bandwidth extension will be proposed. It is hoped that this research can provide theoretical support for wide-band optimization design of vibrator structure and individualized exploration. It is of great significance for the vibroseis to improve the excitation accuracy, achieve wide-band excitation and increase its exploration capability.