A Comparison of Prestack Reservoir Attributes Using Different 3D Prestack Migration Methods

Even when subsurface velocities vary only moderately, accurate imaging of reservoir attributes in depth remains a challenge. Two crucial components of the solution are the determination of an accurate velocity model and the use of an appropriate imaging algorithm. We examine the depth accuracy and qualitative AVO response of images generated using different velocity models and different imaging methods. We conclude that velocities determined from offset checkshot data in conjunction with a 3-D Kirchhoff imaging algorithm yield prestack images whose depths and amplitudes are in better agreement with well data than 3-D prestack migration implemented as a multi-step process (MZO cascaded with zero offset migration).