Integrated Analysis of Shallow Fluid Flow Phenomena and Hydrocarbon Migration in the Southern Kwanza Basin, Offshore Angola
Integrated analysis of high-quality three-dimensional (3D) seismic data, surface geochemistry, and satellite imagery in the southern Kwanza Basin document the widespread occurrence of past and present fluid flow phenomena, and highlights the hydrocarbon prospectivity of the post-salt interval. Seismic scale fluid flow phenomena are defined by seep-related seafloor features including pockmarks, extrusive features interpreted as mud or asphalt volcanoes, and the uncommon occurrence of gas hydrates pingoes. Shallow fluid flow phenomena are characterized by the presence of paleo-pockmarks, direct hydrocarbon indicators (DHIs), bottom simulating reflections (BSRs), and pipes. Seabed evidences of migrated thermogenic hydrocarbons and satellite seepage slicks are used to differentiate hydrocarbon migration from shallow fluid flow processes including dewatering and biogenic gas migration. The analysis constrains the fluid plumbing system defined by the spatial occurrence of stratigraphic carriers and seal bypass systems through time. Detailed integrations and iterative interpretations have confirmed the presence of mature source rock and effective migration pathways with significant implications towards petroleum systems analysis of the post salt interval. Integration of seismic, geochemistry and satellite data represents a robust method to document and interpret fluid flow phenomena along continental margins, and highlight the importance of fluid flow studies with regards to petroleum system analysis and hydrocarbon prospectivity in challenging, high-cost deep-water exploration settings.
AAPG Datapages/Search and Discovery Article #90189 © 2014 AAPG Annual Convention and Exhibition, Houston, Texas, USA, April 6–9, 2014