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逆时偏移方法利用双程波算子模拟波场的正向和反向传播,通常采用互相关成像条件获得偏移剖面,是一种高精度的成像方法.但是传统的互相关成像条件会在偏移结果中产生低频噪声;此外,如果偏移速度中存在剧烈速度变化还可能进一步产生偏移假象.为了提高逆时偏移的成像质量,可在成像过程中先对震源波场和检波点波场分别进行波场分离,然后选择合适的波场成分进行互相关成像.本文基于Hilbert变换,推导了可在偏移过程中进行上下行和左右行波场分离的高效波场分离公式以及相应的成像条件,结合Sigsbee 2B合成数据,给出了不同波场成分的互相关成像结果.数值算例结果表明,采用本文提出的高效波场分离算法以及合理的波场成分互相关成像条件可以获得高信噪比的成像结果.
The reverse time migration method uses the two-way wave operator to simulate the forward and backward propagation of the wavefield, and usually adopts the cross-correlation imaging condition to obtain the offset profile, which is a high-precision imaging method. However, the traditional cross-correlation imaging conditions In addition, there may be further migration artifacts if there is a violent velocity variation in the migration velocity.In order to improve the imaging quality of the inverse time migration, the source wavefield and the detection wave Point wavefield separately and then select the appropriate wavefield components for cross-correlation imaging.In this paper, based on the Hilbert transform, the efficient wavefield separation formula for the wavefield separation of up and down and left and right traveling waves can be derived and The corresponding imaging conditions, combined with the synthetic data of Sigsbee 2B, give the cross-correlation imaging results of different wavefield components.The numerical results show that using the proposed algorithm and the reasonable wavefield cross-correlation imaging conditions Get high signal-to-noise imaging results.