论文部分内容阅读
在石油地震勘探中，由于近地表层速度和厚度的变化，使常规叠加剖面的同相轴受到破坏，常导致假构造现象。为此，本文提出一种近地表层地震层析成像法。该法利用地震勘探中单炮记录的初至波，求取连续变化的近地表层速度分布结构。计算中采用打靶法的两点射线追踪完成地面炮点与接收点间回折波的射线追踪，以形成迭代反演时用的线性方程组和相应的雅可比矩阵。然后，用收敛速度较快的最小二乘共轭梯度法（LSCG）求线性方程组的解。对理论模型的计算结果表明，该方法是可行的，是消除近地表层异常对地震资料影响的有效手段。
In the oil seismic exploration, due to the changes of the velocity and thickness of the near surface layer, the events of the conventional superimposed sections are destroyed, often resulting in the phenomenon of fake structure. Therefore, this paper presents a near surface tomography method. This method uses the first arrival recorded by a single shot in seismic exploration to determine the continuously changing near-surface velocity distribution. In the calculation, the two-point ray tracing by shooting method is used to complete the ray tracing of the return wave between the ground shot and the receiving spot to form the linear equations and the corresponding Jacobian matrix for iterative inversion. Then, the solution of the system of linear equations is obtained using the least-squares conjugate gradient method (LSCG) which has a faster convergence speed. The calculation results of the theoretical model show that this method is feasible and is an effective method to eliminate the influence of the near surface anomalies on the seismic data.