PALAEO-ENVIRONMENT, DIAGENESIS AND CHARACTERISTICS OF PERMIAN BLACK SHALES IN THE LOWER KAROO SUPERGROUP FLANKING THE CAPE FOLD BELT NEAR JANSENVILLE, EASTERN CAPE, SOUTH AFRICA: IMPLICATIONS FOR THE SHALE GAS POTENTIAL OF THE KAROO BASIN

2015 ◽  
Vol 118 (3) ◽  
pp. 249-274 ◽  
Author(s):  
C. GEEL ◽  
M. DE WIT ◽  
P. BOOTH ◽  
H-M. SCHULZ ◽  
B. HORSFIELD
Keyword(s):  
South Africa ◽  
Shale Gas ◽  
Black Shales ◽  
Eastern Cape ◽  
Fold Belt ◽  
Karoo Basin ◽  
Cape Fold Belt ◽  
Gas Potential

Seismic imaging of dolerite sills and volcanic vents in the Central Karoo, South Africa: implications for shale gas potential

2021 ◽  
Author(s):  
S.E. Scheiber-Enslin ◽  
M. Manzi ◽  
S.J. Webb
Keyword(s):  
South Africa ◽  
Shale Gas ◽  
Global Climate ◽  
Magnetic Data ◽  
Seismic Reflection Profile ◽  
Magnetic Studies ◽  
Seismic Line ◽  
Seismic Section ◽  
Karoo Basin ◽  
Gas Potential

Abstract The Karoo Basin of South Africa covers an area of 700 000 km2 and has been identified as a possible shale gas reserve. Any evaluation of the shale gas potential of the basin must consider the widespread dolerite dykes and sills. These intrusions were emplaced into the Karoo Supergroup and are well dated at around 183 Ma. Their intrusion triggered the explosive releases of gas in the basin, marked on surface by breccia pipes and hydrothermal vents. This outpouring of gas has been proposed as a significant contributor to global climate change. Research into the three-dimensional interconnected structure of these dolerite sills and dykes and their interaction with the hydrocarbon rich layers in the lower part of the Karoo Supergroup has been limited to localized observations of outcrop, magnetic data, legacy seismic data (from the 1970s) and well core. Here we present an interpreted 65 km long higher-resolution 2D seismic reflection profile across the Karoo Basin, approximately 100 km southeast of Trompsburg. These data were collected in the 1990s and at the time deeper structures along the line interpreted. In this study we focus on the top 0.6 to 2 seconds TWT of the data. The seismic line images the interconnected and cross cutting nature of the dolerite dykes and sills along the profile. We also report possible evidence of a gas escape structure (approximately 2.5 km in diameter at surface) emerging near the edge of a dolerite sill in close proximity to the Whitehill Formation, which is the main target for shale gas exploration. This suggests that gas vents in the eastern Karoo Basin close to Lesotho are due to the release of gas from the carbonaceous shales of the Ecca Group. This is similar to breccia pipes mapped on surface in the western part of the Karoo Basin. This seismic section highlights why dolerite sills and dykes must be considered when evaluating the shale gas potential of the Karoo Basin. We propose that better characterization of the Karoo Basin subsurface by seismic and magnetic studies is necessary prior to any efforts to calculate shale gas reserves.

scholarly journals Shale Gas Characteristics of Permian Black Shales in South Africa: Results from Recent Drilling in the Ecca Group (Eastern Cape)

2013 ◽  
Vol 40 ◽  
pp. 256-265 ◽  
Author(s):  
Claire Geel ◽  
Hans-Martin Schulz ◽  
Peter Booth ◽  
Maarten deWit ◽  
Brian Horsfield
Keyword(s):  
South Africa ◽  
Shale Gas ◽  
Black Shales ◽  
Eastern Cape

Geochemical Evaluation of the Permian Ecca Shale in Eastern Cape Province, South Africa: Implications for Shale Gas Potential

2018 ◽  
Vol 92 (3) ◽  
pp. 1193-1217 ◽  
Author(s):  
Christopher BAIYEGUNHI ◽  
Kuiwu LIU ◽  
Nicola WAGNER ◽  
Oswald GWAVAVA ◽  
Temitope L. OLONINIYI
Keyword(s):  
South Africa ◽  
Shale Gas ◽  
Eastern Cape Province ◽  
Eastern Cape ◽  
Geochemical Evaluation ◽  
Gas Potential
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