【摘要】 由于广义线性反演的局限性,由旅行时残差,层析反演无法同时准确反演速度值和界面几何形态。提出了一种以已知速度信息作为约束条件,从浅到深分层约束反演地震速度的方法。该方法以微测井资料对小折射初至波进行约束层析反演,获得比较准确的极浅层速度场;以得到的极浅层层速度和低降速带资料约束大炮初至波层析反演,得到了精度更高的近地表速度模型和静校正量;以静校正计算中用充填速度替换低降速带后获得的速度模型,作为浅层反射波层析的初始约束条件,可提高浅层偏移速度建模精度;用VSP、地球物理测井速度约束反射波层析反演,得到精度更高的中深层偏移速度场。实际资料处理结果表明,该方法明显提高了层析反演精度,获得了更准确的速度场,改善了叠前偏移成像效果。更多还原

【Abstract】 Because of the limilation of generalized linear inversion,tomography inversion cannot simultaneously accurately invert velocity and surface geometry from residual error of traveltime.Aiming at the problem,we propose a method which adopts known velocity information as constraint condition and invert seismic velocity from shallow to deep layers.By using this method,constrained tomography inversion is carried out on small-refraction first-arrival based on uphole and achieves relatively accurate velocity field of extremely shallow layers.Then,the velocity field of extremely shallow layers and the velocity of low-velocity zone are regarded as constraint for first-break tomography inversion to obtain higher-precision near-surface velocity model and statics.The velocity model obtained from static correction computation with the filling velocity replacing the velocity of low-velocity zone is regarded as the initial constraint condition for shallow reflection wave tomography inversion to improve the precision of migration velocity modeling in shallow layers.The VSP and geophysical logging velocity is used to constrain the reflection wave tomography inversion to obtain high-precision migration velocity field in middle-deep layers.Actual data processing results indicate that the method can largely improve the accuracy of tomography inversion and obtain more accurate velocity field to eventually enhance the pre-stack migration result.更多还原