叠前时间偏移在煤田复杂构造勘探中的应用

Application of pre-stack time migration in the exploration of complex structures in coal fields

研究区内地质构造发育比较复杂,为优化开采,急需查明区内断层、采空区等隐伏地质构造展布特征。煤田资料处理中,叠后时间偏移绕射波难以归位,资料解释存在多解性、解释精度低等问题。对此,本文讨论了弯曲射线Kirchhoff保幅叠前时间偏移的适用范围。在高精度静校正、叠前保幅去噪、振幅补偿、反褶积等资料处理前期工作的基础上,通过精细迭代偏移速度、优选孔径、反假频算子等偏移参数,完成了区内的资料偏移成像处理。应用效果表明,Kirchhoff叠前时间偏移的精度明显高于叠后时间偏移,提高了断层、采空区等构造的解释精度,降低了资料解释的多解性。通过保幅叠前偏移处理,保持了断层、采空区等煤田构造的振幅响应特征,提高了断层、采空区的分辨率。因此,在此类复杂构造的三维煤田勘探中,采用保幅叠前时间偏移处理是必要的手段。

The development of geological structures in the study area is relatively complicated. In order to optimize mining,it is urgent to find out the distribution characteristics of hidden geological structures such as faults and goafs in the area. In coal field data processing, the post-stack time-migration diffraction wave is difficult to return to its place, and data interpretation has problems such as diversification and low interpretation accuracy. The article discusses the scope of application of Kirchhoff pre-stack time migration for bending rays. On the basis of the preliminary work of data processing such as high-precision static correction, pre-stack amplitude preservation and denoising, amplitude compensation,deconvolution, etc., through fine iterative migration speed, preferred aperture, anti-aliasing operator and other migration parameters, the data in the area is offset imaging processing. The application results showed that the accuracy of Kirchhoff pre-stack time migration was significantly higher than that of post-stack time migration, which improved the interpretation accuracy of faults, goaf areas and other structures, and reduced the ambiguity of data interpretation. The amplitude-preserving pre-stack migration process maintains the amplitude response characteristics of faults and goafs and other coalfield structures, thereby improving the resolution of faults and goafs. Therefore, in the exploration of such complex structures in 3 D coalfields, it is necessary to use pre-stack time migration processing to maintain amplitude.