An investigation of constant velocity gradient effects in seismic analysis

Abstract

Information concerning acoustic velocities plays an important role in seismic analysis. Acoustic velocity of the medium can be approximated by a polynomial function of depth. The concept that velocity varies linearly with depth has been considered by many researchers as an appropriate assumption for developing the velocity profile for a medium. -- In this study the linear velocity profile approach has been used to estimate the parameters of the medium. The normal moveout relationship for a single zero-dipping reflector has been derived. A methodology for obtaining the parameters such as the reflector geometry and the constant velocity gradient of the medium from the surface observable x-t data is presented. -- Further, the linear velocity profile model for a sloping reflector has been derived based on the normal ray analysis. Based on the knowledge of the velocity profile the least squares technique has been used to identify the reflector geometry from reflection data. The x-t data has been obtained by shifting the shot/receiver position progressively. A comparative analysis has been made to obtain the effect of constant velocity gradient in seismic analysis.