Interpretive Processing - Combining Data Driven Velocity Modelling and Geological Knowledge for

摘要

Imaging off the east coast of India poses a specific set of challenges for velocity model building and the migration. Significant topographical variation in the sea bed gives rise to numerous effects which must be dealt with starting with the water velocity that varies with depth and distance from the sub-continent, deep channels and steep slopes, buried channels with low velocity fills and gas hydrates. Deeper down the section one encounters velocity variations introduced by regional unconformities and re-deposition (slumps, canyon cuts and cut and fill areas). The east coast of India has evolved through a multiple cycle of tectonic and sedimentary processes and has been subdivided into several basins. The younger depositional units present a variety of facies ranging from deep marine channel-level to complex canyon fills. In this paper, we describe an approach to tackling such problems for data from the Krishna-Godavari and the Mahanadi Basins off the east coast of India, concentrating our attention on iterative velocity model building, more specifically the resolution of near-seabed and post-Cretaceous velocity anomalies.