高精度速度建模和高斯射线束深度偏移技术在渤海地区的应用

High-Resolution Velocity Model Building and Gaussian Beam Depth Migration Technology

为解决渤海地区地震勘探中存在的次生断层发育区、高陡构造区、局部速度异常区和潜山内幕等复杂构造区域的地震成像问题,提出了一种以高精度速度建模为基础,应用高斯射线束深度偏移改善复杂构造成像质量的技术方法。高精度速度建模是配合倾斜横向各向同性(TTI)速度模型,利用高精度层析反演技术得到较准确的速度模型。高斯射线束偏移方法是弹性动力学方程集中于射线附近的高频渐近时间调和解,它克服了标准射线方法在焦散面附近振幅急剧、不固定变化的缺点,在复杂构造区也能保证正常响应。实际资料处理表明,两种技术在渤海地区的联合应用改善了高陡构造和复杂断裂的成像质量,有效提高了地震资料的品质。

To solve the imaging bottlenecks in the seismic exploration of complicated structural zones in Bohai Sea region, such as for the secondary fault development zone, high steep structural zone, regional velocity abnormality zone and buried hill inner curtain zone, this article comes up with a technical method which is based on high-resolution velocity model building and uses Gaussian beam depth migration for improvement of complicated structural imaging quality. High-resolution velocity model building is for the purpose to work with TTI velocity model and use high-resolution tomographic inversion technology to obtain more accurate model. Gaussian beam depth migration method is the high-frequency asymptotic time harmonic solution of elastodynamic equation concentrated near rays. It overcomes the shortcomings of standard ray method that the amplitude changes sharply and non-fixedly near the caustic surface. It can also ensure normal response from complicated structures. Actual data processing indicates that joint application of the two technologies improves imaging quality of high steep structures and complicated faults in Bohai Sea region, thus improving the quality of seismic data.