Remote Sensing & Geomatics, KDMIPE, ONGC, Dehradun davharsh@gmail.com P-037 Mapping Hydrocarbon seepages using satellite SAR data in Eastern Offshore - Essential Input in Oil Exploration H.D Dave, S. Mazumder, J.K. Samal, K.K.S. Pangtey and D.S. Mitra, ONGC Summary Hydrocarbon seepages in oceans are direct indicators of the existence of a petroleum system under the sea bed. Active microwave radar or SAR (Synthetic Aperture Radar) provides a powerful and cost effective mode to detect such oil seepages. In this paper an attempt had been made to understand the relationship between the seepages and probable hydrocarbon prospects in the Eastern Offshore regions of India. Based on SAR data, regions of seepage repetitions had been detected and are found to be associated with faults and tectonic elements attached with source pods suggesting that seepages are manifestations of active migration, mature source and a shallow reservoir. Using the same premises and the same methodology, a possible hydrocarbon system had also been envisaged in the isolated and distally located 85 E Ridge Introduction Hydrocarbon seepages in oceans are direct indicators of the existence of a petroleum system implying possible rich hydrocarbon resources under the sea bed. Hence detection of such seepages helps in lowering the cost and risk involved in the exploration activities as well as provides a guideline for petroleum prospectivity assessment and exploration in the region. The space-borne active microwave radar or SAR (Synthetic Aperture Radar) provides a powerful and cost effective mode to detect such oil seepages with its ability of wide area coverage, high temporal resolution, cloud penetrating ability as well as consecutive day and night coverages of any area. Seeps are surface expressions of migration pathways of hydrocarbons where leaking hydrocarbons seeping out of faults or conduits opening in the sea bed migrate to the sea surface due to their buoyancy in the form of thin oil films covering bubbles of gas. At the sea surface, these gas bubbles burst with the oil films forming oil layers on ocean surface. In normal conditions, capillary waves on the sea surface reflect the radar energy to produce a bright image known as the Sea Clutter. However, if oil is present in the sea surface, it dampens the wave signature in the microwave ranges and is detected as a dark area on a bright sea surface in SAR images (Fig 1). A detailed description about the methodology and processing of SAR images to detect seepages had been dealt in Dave et al, 2011. In this paper hydrocarbon seepages in the eastern offshore basins of India that had been detected by SAR studies had been documented and subsequently compared with the tectonic elements and petroleum systems of the area in an attempt to understand the relationship between the seepages and probable hydrocarbon prospects in the area.