摘要
高陡山区的近地表速度变化剧烈 ,严重影响着深层地震成像质量 ,搞清近地表速度结构是提高地震处理质量的首要任务。折射波走时包含地下浅层的速度信息 ,采用程函方程有限差分法计算通过速度模型的初至旅行时射线路径 ,然后使用约束最小二乘正交分解法进行走时反演 ,从而获得近地表速度结构。这种层析反演方法以块体为基本单元 ,可以处理直达波、折射波和透射波 ,模拟和反演复杂速度结构 ,不用识别波形 ,计算速度快。对我国西部某高陡山区 (最陡处坡度超过 45°)实际数据进行层析反演 ,该逆掩山体的山下与山顶近地表初至时间相差近 4倍 ,而且山顶地表为低速。
The near-surface velocity in mountain regions varies strongly, which seriously affects seismic imaging quality. The first task of improving seismic processing quality should be tried to get the near-surface velocity. The refraction travel time contains the velocity information of shallow intervals underground. The near-surface velocity structure can be obtained through inverting travel time, via first the finite-difference scheme to eikonal equation to calculate trace paths and then the constrained LSQR. This kind of tomography inversion with a rectangular block cell, that could process the directive wave and refraction as well as transmission wave, can model and invert the complex velocity structure. It is unnecessary to cognize wave styles and it calculates velocity quickly. The tomographic result to field data having a character of high and steep mountain (the slope of the steepest part over 45°) in west China shows that the difference of shallow near-surface velocities at hill-top and at foot achieves about 4 times and the velocity at the hill-top is very low.
出处
《石油勘探与开发》
SCIE
EI
CAS
CSCD
北大核心
2000年第2期60-61,共2页
Petroleum Exploration and Development
关键词
高陡山区
近地表速度
地震勘探
地震资料处理
Seismic data processing, First refraction break, Finite difference method, Inversion, Near-surface velocity, Tomography
