Seismic Texture of Tertiary Successions: Insights from Tipam and Barail Formations in the Upper Assam Basin, NE India

Abstract

This work uses high-quality 3D seismic data from the historic oil-producing province of NE India in the Upper Assam Basin for the investigation of structural architecture and textural characteristics that have modulated the Barail and Tipam Formations of the Tertiary successions. The seismic volume was structurally conditioned to improve the contrast at seismic reflectors and thereby preserving their lateral continuity. The conditioned data are interpreted in combination with seismic attributes to examine the seismic textural responses in the interval of interest between the Barail and Tipam formations. The study brings out that the Barail coal-shale unit is associated with deformed, wavy, chaotic and heterogeneous textures, which suggest a deeper basinal condition prevailing during the deposition. However, molassic texture associated with less chaotic and high homogeneity of reflections indicate the occurrence of fluviatile environment that prevailed during the deposition of the Tipam sandstone unit. It is observed that structural compartments within the Miocene interval act as different trap networks for encasing migrated hydrocarbons from the Oligocene source interval. The finding establishes a relationship between the structural and depositional set-ups within the litho-units of the Tertiary successions for plausible hydrocarbon accumulation in the upper Assam basin.