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川东地区地表条件极为复杂,地形起伏大,构造顶部多出露二叠系、三叠系碳酸盐岩。地腹地层强烈褶皱,地层倾角大,直立甚至倒转,逆冲断层发育。地震原始资料的声波、面波、侧面波及其它干扰波能量较强。由于受回转波、侧面波、绕射波等互相干涉和速度横向变化的影响,叠加剖面成像质量较差,造成构造形态失真。本文针对川东地区高陡复杂构造的特殊情况,首先采取了提高叠前资料的信噪比,然后在建立合理的构造模式的基础上,建立正确的偏移速度模型(速度模型包括界面形态和速度值)和选用合适的偏移方法(本文采用了叠前深度偏移)。利用本文的方法,对川东高陡构造复杂区的多条测线进行了重新处理,使叠加剖面上的反射波归位和偏移成像质量有明显的提高。
The surface conditions in eastern Sichuan are extremely complicated with large topography and undulation. Most of Permian and Triassic carbonate rocks are exposed at the top of the structure. Strong belly layer fold, stratum dip angle, vertical or even inversion, thrust fault development. Sound waves, surface waves, side waves and other interference waves of the original seismic data have stronger energy. Due to the interference of the rotating wave, the side wave, the diffraction wave and so on, and the transverse variation of the velocity, the imaging quality of the superposed profile is poor, resulting in distortion of the structural shape. In this paper, aiming at the special situation of high and steep complex structures in eastern Sichuan, firstly, the signal-to-noise ratio of prestack data is improved, and then the correct migration velocity model is established based on the establishment of a reasonable tectonic model Speed value) and select the appropriate offset method (in this paper, prestack depth migration). Using the method in this paper, a number of measurement lines in the high and steep structural complex areas in eastern Sichuan have been reprocessed so that the reflection wave homing and migration imaging quality on the superimposed sections can be obviously improved.