South Africa - Inkaba.org

Seismic Interpretation, Distribution, and Numerical Modelling
of Natural Gas Leakage in Block 2 of the Orange Basin,
Offshore South Africa
Donna Boyd 1 , Maarten de Wit 2 ,Zahie Anka 3 , Rolando di Primio 4
1. AEON, University of Cape Town, South Africa, boyd.donna@gmail.com
2. AEON, University of Cape Town, South Africa, maarten.dewit@uct.ac.za
3. GFZ German Research Centre for Geosciences. Potsdam, Germany, zahie@gfz-potsdam.de
4. GFZ German Research Centre for Geosciences. Potsdam, Germany, dipri@gfz-potsdam
ABSTRACT
300 2D seismic profiles and 10 wells were analysed from the study area of 18750 km 2 in exploration Block 2 of
the Orange Basin located offshore the South African continental margin. The aims of this study are to: (1)
characterize different natural gas leakage features present throughout the basin, and (2) understand the relationship
of natural gas leakage with structural and stratigraphic elements, and (3) quantify liquid/gas hydrocarbon
generation, migration and seepage dynamics through the post-rift history of the basin. Methane gas escaping across
the sea floor into the exosphere may contribute to Earth’s climate fluctuations. Since a significant volume of
escaping gas was cut off when at least half of identified structurally-controlled chimneys were sealed within the
Miocene sequence, retention of gas along this continental margin may have to be factored into global cooling
models.
KEYWORDS: volcanic continental margin, South Atlantic, Orange Basin, natural gas leakage, gas chimneys,
South Africa
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