Time lapse imaging by separate and joint least squares prestack Kirchhoff migration

Abstract

Different acquisition geometries of the baseline and monitor seismic surveys produce different patterns of acquisition footprints. The resulting time lapse image shows the differences in artifacts, which may dominate the changes in the reflectivity model due to the production from or injection into the reservoirs. Synthetic data is used to show how different acquisition geometries between baseline and monitor surveys lead to different Kirchhoff migration artifacts for the same reflectivity model. The least squares prestack Kirchhoff migration (LSPSM) is performed separately on the baseline and monitor data to attenuate these effects and provide comparable high resolution images for both pre- and poststack time lapse studies. A joint least squares Kirchhoff prestack migration (LSPSM) of both baseline and monitor data is introduced which attenuates the migration artifacts and returns high resolution LSPSM and/or time lapse images.