The Bottom Simulating Reflector (BSR) Along the Brazilian Atlantic Coast: A New Perspective for Gas Hydrates Exploration in the Southern Hemisphere

Nilo S. Matsuda and Antonio F. Freire
E&P/EXPLORATION/GEO, PETROBRAS S. A., Rio de Janeiro, Brazil

At least three prominent BRS`s (Bottom Simulating Reflectors) signatures are mapped within the Upper Tertiary sedimentary rocks along the 6,000km of the Brazilian Atlantic Passive Margin Coast. The one of stronger visible BSR come from the southernmost part of Brazilian offshore named Pelotas Basin. The area with BSR covers about 45,000km² within the Rio Grande Cone and range from 500m to 3,500m of water depth. It is considered by many experts, as one of the largest area in the world.

The disseminated gas hydrates volume associated with the sedimentary rocks of about 600m in thickness can draft far 780 TCF (trillion cubic feet). The second case is related to a new BSR signature measuring about 600m thick discovered along the eastern region of Brazil at the northern part of Santos Basin. The water depth ranges from 1,950m to 2,050m and this BRS is still under evaluation. The northernmost BSR occurrence, around the Amazonas River Cone is characterized by several visible bright seismic signatures mapped through an area of about 28,000km². The water depth varies from 600m to 2,800m. The detected thickness of rock holding disseminated gas hydrates is near 450m and the expected volume can exceed 430 TCF. The understanding and development of BSR`s mapped along the Brazilian Atlantic Coast is a challenge. The gas hydrates exploration programs along the Brazilian Passive Margin can be considered a new frontier area and become an attractive investment facing the increase demand on energy.

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