Velocity-less time migration in application to hard rock environments

Abstract

Reflection seismic method has a number of constraints to obtain suitable images in hard rock environment. For many seismic migration algorithms it is necessary to know the values of propagation velocity of seismic waves. In sedimentary basins, where layers are usually continuous reflectors, that information could be obtained directly from acquired data. However in hard rock environments there are a lack of such horizontal boundaries. This presents a difficulty for an estimation of the velocity model, so obtaining a satisfactory image in hard rock environments is not a trivial problem. Imaging algorithms that do not require prior construction of a velocity model might be promising for such media. Here we describe an application of a velocity-less time migration to hard rock conditions and demonstrate its effectiveness on synthetic data. This approach is based on an estimation of horizontal slownesses in commonshot and common-receiver gathers and a following calculation of the migration attributes. The algorithm was tested on simple convolution synthetic models and applied to 2D synthetic dataset, which simulate a common geological section in hard rock media.