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复杂地表的静校正问题往往被归结为近地表层速度的求解问题,地表越复杂,近地表速度的求解就越困难。针对塔里木盆地沙漠地区地表条件异常复杂、原始资料信噪比低、静校正问题突出的特点,首先在表层结构分析的基础上进行静校正方法的研究,先后应用了初至折射静校正、沙丘曲线静校正和层析反演静校正法;根据沙丘内部地震波传播速度与沙丘厚度有关,提出了对沙丘曲线方法的改进,即根据v(hi)与实测值vi之间的偏差δi来计算(∑δ2i)~(1/2)和max|δi|,如果在事先给定的误差范围内,则认为拟合有效。实际中往往采用二次或三次多项式拟合来求取近地表速度。处理结果表明:用多项式拟合求取表层速度的静校正法在沙漠地区是切实可行的,为沙漠地区表层速度的求取提供了新的途径。
The problem of static correction of complex surface is often attributed to the solution of near-surface velocities. The more complex the surface, the more difficult it is to solve near surface velocities. Aiming at the characteristics of complex surface conditions in the desert area of Tarim Basin, low signal-to-noise ratio of original data and prominent static correction problems, the static correction method is firstly studied based on the analysis of surface structure. The initial static refraction statics, Static correction and tomographic inversion static correction method. According to the relationship between seismic wave propagation velocity and sand dune thickness, an improvement on the dune curve method is proposed. That is to say, the deviation of δ (Σ δ2i) ~ (1/2) and max | δi |, the fitting is valid if it is within a given error range. In practice, quadratic or cubic polynomial fitting is often used to obtain near-surface velocities. The results show that the static correction method of obtaining surface velocities by polynomial fitting is practicable in the desert area and provides a new way to obtain the surface velocity in the desert area.