论文部分内容阅读
与传统深度偏移成像方法相比,基于双程波的逆时偏移方法针对地下陡倾角地区和复杂地下地质条件地区的成像有着无可比拟的优势。逆时偏移方法的实现通常有3个步骤:①在时间域实现震源波场的正向外推;②在时间域实现检波点波场的反向外推;③应用合理的成像条件构建成像结果。在实际应用过程中,通常是采用互相关成像条件来构建成像,然而,互相关成像条件构建的逆时偏移成像结果会产生强振幅的低频噪音,这些噪音会极大地降低资料的信噪比,容易导致浅层构造被噪音掩盖而无法识别,仅采用单纯的带通滤波并不能很好地滤除这种噪音。提供了一种新的基于波场分离理论的逆时偏移成像条件,此方法能有效地消除这些特定的噪音,其核心思路就是将震源及检波点波场分离成它们的单程波传播分量,然后仅在反射点处利用互相关的成像条件构建成像结果,从而实现逆时偏移成像。Marm-ousi模型数据验证了该方法的准确性;同时,采用文中提到的成像条件在准噶尔盆地百口泉地区进行了逆时偏移测试,测试结果充分证明新成像条件对野外资料的适应性。
Compared with the traditional depth migration imaging method, the TWT method based on two-way wave has an unparalleled advantage for the imaging in steep dip fields and complex geological conditions. There are usually three steps to achieve the inverse time migration method: ① Forward extrapolation of the source wavefield in the time domain; ② Reverse extrapolation of the wavefield in the time domain; ③ Imaging using reasonable imaging conditions result. In practice, cross-correlation imaging conditions are commonly used to construct the image. However, the inverse time migration imaging results of the cross-correlation imaging conditions produce strong amplitudes of low-frequency noise that can significantly reduce the signal-to- , Easily lead to shallow structure covered by the noise can not be identified, only using a simple band-pass filter does not filter out this noise well. A new inverse time migration imaging condition based on the wave field separation theory is provided. This method can effectively eliminate these specific noises. The core idea is to separate the source and detector wavefields into their one-way wave propagation components, The imaging results are then constructed using only cross-correlated imaging conditions at the reflection point to achieve inverse time migration imaging. Marm-ousi model data verify the accuracy of the method; meanwhile, using the imaging conditions mentioned in the article in the Baijianquan area of the Junggar Basin to conduct a reverse time migration test, the test results fully proved the adaptability of the new imaging conditions to the field data .