Artifact-free reverse time migration

We derive an improved reverse-time migration scheme to image the medium without artefacts arising from internal multiple reflections. This is based on a revised implementation of Marchenko redatuming using a new time-truncation operator. Because of the new truncation operator, we can use the time-reversed version of the standard wavefield-extrapolation operator as initial estimate for retrieving the upgoing focusing function. Then, the retrieved upgoing focusing function can be used to directly image the medium by correlating it with the standard wavefield-extrapolation operator. This imaging scheme can be seen as an artefact-free reverse-time migration scheme with two terms. The first term gives the conventional reverse-time migration image with wrong amplitude and artefacts due to internal multiple reflections. The second term gives a correction image which can be used to correct the amplitude and remove artefacts in the image generated by the first term. We illustrate the method with a two-dimensional ...