隐蔽致灾地质体三维叠前绕射波稀疏分离与动力学成像机制研究

The small-scale hidden and hazard geological anomalies, such as faults and collapsed columns, may destroy the continuity of layers and result in dangerous mining accidents including gas outburst and water burst. The traditional seismic exploration method mainly involves with reflections and is unable to effectively identify these small-scale geologic anomalies, because of its limited resolution. This project intends to focus on a 3D prestack shot-domain diffraction sparse separation and angle-domain dynamic imaging method. First, the sparse curvelet transform and plane wave decomposition are combined to form a multiple-parameter sparse optimization model for separating the waveform-consistent and integrity diffractions, especially in the case of intersection and tangency of seismic wavefield. Secondly, breaking through the traditional framework of reflection velocity analysis, a diffraction velocity analysis method in the migrated dip-angle domain is constructed using a minimum variance beamformer technique, to further focus the diffractions in the outer regions beyond the first Fresnel aperture. Finally, by studying the law of diffraction amplitude and polarity with variation of the azimuth and emergence angle, a 3D angle-domain dynamic diffraction imaging method is proposed to achieve the high-resolution capability. This project has a great potential to resolving the small-scale hidden and hazard geological anomalies such as faults and collapse columns, and plays a great significance in ensuring the safe and efficient coal mining in China.

小尺度断层和陷落柱等不连续构造破坏煤层连续性，具有隐蔽性，易于诱发瓦斯突出和采空区突水等事故，严重威胁煤矿生产安全。传统地震勘探方法以反射波为主，分辨率有限，无法对之有效识别。本项目拟研究三维叠前炮域绕射波稀疏分离与角度域动力学成像方法，首先基于curvelet稀疏变换和平面波分解构建多参数稀疏优化绕射波分离模型，解决在地震波场相交和相切情况下绕射波分离问题，使得分离的绕射波具有波形一致性和完整性；其次，利用最小方差波束准则研究偏移倾角域绕射波速度分析方法，突破常规的反射波速度分析框架，解决第一菲涅尔孔径之外的绕射波准确归位问题；最后，利用绕射波极性和振幅随出射角和方位角变化规律，研究三维角度域绕射波动力学成像机制，达到高分辨率成像目的。本项目有望解决小尺度断层和陷落柱等隐蔽致灾地质体探测难题，为我国煤矿安全高效开采提供技术保障。

我国煤矿安全事故频发，其中断层、陷落柱及采空区等不良地质体是主要灾害源。该类隐蔽地质体的地震响应通常表现为绕射波弱信号，本项目通过研究绕射波分离及其动力学特征形成了一种精细化地震成像方法。项目研究内容与主要成果:①构建了三维叠前炮域多参数稀疏优化绕射波分离方法，提高了复杂波场干涉情况下绕射波分离的波形一致性和完整性；②考虑了复杂介质中绕射波多支出射线特征，利用改进的自适应最小方差波束形成算子，发展了偏移倾角域绕射波速度分析方法，实现了绕射波弱信号聚焦叠加与精细速度建模；③基于角度域绕射波的极性与振幅等动力学特征，针对不连续地质构造与非均质地质体，构建了不同类型绕射波成像机制。研究工作在理论上丰富了煤矿地球物理学，在实际应用中获得了工业界的肯定，为煤矿地质灾害防治提供了技术支撑。项目研究发表了SCI收录论文12篇，授权国家发明专利7项,培养博士2人,硕士3人。