Uplift of the Namibian Passive Margin and Its Potential Implications from Hydrocarbon Generation in the Luderitz Basin

Matthew Laughland¹, Neil Judge¹, and Paul F. Green^2
1Hunt Oil Company, Dallas, TX
²Geotrack International Pty. Ltd., Brunswick West, VIC, Australia

An integrated interpretation of new data acquired in the Luderitz basin, offshore Namibia, has led to an improved understanding of the hydrocarbon potential. The basin has large undrilled structures and widespread seismic indicators of an active hydrocarbon system, including BSRs and gas chimneys. However, the basin is largely unexplored with a single exploration well, the 2513/8-1.

The purpose of this study is to examine the timing of tectonic and thermal events that may have led to hydrocarbon generation.
Simple 1D basin modeling based on present-day geothermal gradients (~34°C/km.) and measured values of vitrinite reflectance for the 2513/8-1 well indicates that the sedimentary section was hotter in the past. Apatite fission track analysis for the well broadly confirms that the timing of cooling from maximum paleotemperature was during Paleocene to Eocene time (65 - 25 Ma.). This age is further refined to between 60 and 55 Ma. by incorporating results from onshore samples. Assuming that the timing of maximum paleotemperature was related to deeper burial, 1D modeling of the 2513/8-1 well requires deposition of an additional 1.1 km. of burial beginning at 65 Ma. and subsequent removal by uplift and erosion between 55 and 45 Ma.

This burial and thermal history reconstruction was used to constrain a 3D model of hydrocarbon generation based on regional mapping of six seismic horizons in the Luderitz basin. Kinetic models of hydrocarbon generation show that a kitchen is located within east-southeastern portions of the basin, and that maturity levels are sufficient for primary oil and gas generation from Aptian age, and to a lesser extent, Cenomanian-Turonian age source rocks, if present. Generation and migration occurred during Tertiary time which favorably post-dates the formation of structural traps and deposition of Cretaceous age reservoir lithologies.

AAPG International Conference and Exhibition, Cape Town, South Africa 2008 © AAPG Search and Discovery