3D seismic analysis of the AK Fault, Orange Basin, South Africa: Implications for hydrocarbon leakage and offshore neotectonics

• Published in: Tectonophysics Vol. 721; pp. 477 - 490
• Main Authors: Isiaka, Ahmed I., Durrheim, Raymond J., Manzi, Musa S.D., Andreoli, Marco A.G.
• Format: Journal Article
• Language: English
• Published: Amsterdam Elsevier B.V 28.11.2017; Elsevier BV
• Subjects: 3D seismics; Activation; Continents; Cretaceous; Diapir; Evolution; Fault lines; Faults; Fluids; Geological faults; Graben; Hydrocarbon leakage; Hydrocarbons; Jurassic; Leakage; Neotectonics; Offshore; Orange Basin; Seismic activity; Seismic analysis; Seismic surveys; Tips; Vertical migration; South Africa; Orange Basin; Diapir; Hydrocarbon leakage; Neotectonics; 3D seismics
• ISSN: 0040-1951; 1879-3266
• DOI: 10.1016/j.tecto.2017.10.011

A high-resolution 3D reflection seismic dataset was used to achieve a detailed description of the half-graben bounded AK Fault in the Ibhubesi gas field of the offshore Orange Basin. Seismic analysis of the fault involved the combination of both the conventional seismic interpretation and seismic attributes. The main objective of the study was to provide insights into hydrocarbon leakage and neotectonic activity along the west coast shelf of South Africa. The AK Fault is among the several half-graben bounded faults that formed in the Late Jurassic to Early Cretaceous during the separation of the South American and the African continents. The AK Fault consists of five seismically detectable segments, whose evolution reflects characteristics of both the “coherent” and the “isolated” end-members model of segmented fault origin. Diapiric structures that are direct indicators of vertical fluid movement were also observed along the AK Fault system, providing evidence of significant roles that the fault plays in promoting the vertical migration of hydrocarbon in the Orange Basin. Recent reactivation of the fault has also occurred along an oblique extensional regime that is dominated by normal dip-slip faulting, with minor shear components along the tips. •3D seismic reflection analysis of a half-graben bounded fault in the Orange Basin.•Vertical migration of fluid along the fault is revealed by diapiric structures.•Evolution of the different segments of the fault reflects both coherent and isolated origin.•The reactivation of the fault has occurred along an oblique extension regime.