For more information, contact Marylin Segall Click here for the poster Seafloor Stability of the Brazilian Continental Margin - Considerations for Offshore Hydrocarbon Exploration and Production Continental shelves and upper slopes of the basins are dominated by reworked Holocene and modern sediments. Integrated characterizations of environmental data and sediment properties are necessary components of a comprehensive basin evaluation. Near-surface sediments are characterized by unique physical properties that have potentially significant effects on prospect economics related to offshore concessions. These parameters affect initial exploration efforts, drilling capability, and eventual recovery. Each basin is characterized by unique antecedent topography and metocean conditions inherited from its proximity to the Mid Atlantic Ridge.
Destructional processes are evident at points of current divergence.
High-resolution shallow seismic reflection profiles depict several types of methane deposits. In each of these formations, gas may be released to the seafloor via adjacent porous sediments or through failure of adjacent or overlying strata. Spatially-discontinuous methane deposits that are stratigraphically controlled may occur within several meters of the seabed. Continuous release of gas as bubbles through adjacent porous media results in a seabed that does not display evidence of deformational processes. Evidence of heave that can extend more than 300 m from the buried channel margins indicates that initial gas release resulted from failure in which the horizontal effective stress was greater than the vertical effective stress.