Inversion tectonics in Central Africa Rift System: Evidence from the Heglig Field

• Published in: Marine and petroleum geology 2017-02, Vol.80, p.293-306
• Main Authors: El Hassan, Waleed Mohamed, Farwa, Abdalla Gumaa, Awad, Mohamed Zayed
• Format: Article
• Language: English
• Subjects: Heglig field; Inversion tectonics; Trap
• ISSN: 0264-8172; 1873-4073
• DOI: 10.1016/j.marpetgeo.2016.12.007

The Mesozoic-Cenozoic tectonic history of the Muglad Basin, is dominated by extension and inversion tectonics, but evidence of the inversion tectonics has not been well documented yet. In some other rift basins of CARS and WARS the phase of the inversion tectonics is well documented by several authors. This paper presents a structural study of the Heglig field area located on the eastern flank of the Muglad Basin. Detailed 3D seismic interpretation allows a better understanding of the structural style of the Heglig field. The new structural analysis has shown that the Heglig field has a complex structural framework reflected in the presence of a combination of two structural styles. The extensional structure is influenced by inversion tectonics during the Santonian time that creates four-way dip anticline structure, overprinted by the subsequent extensional movement that creates tilted fault block. The presence of inversion tectonics has supported by different means including seismic reflection, velocity, and source rock maturity data. The authors attributed the trapping of oil in the Lower Bentiu reservoir, that requires a horizontal seal, to the presence of the four-way dip anticline structure created by the inversion tectonics. The current interpretation of the Heglig field 3D seismic data sheds new light on the development and evolution of a key structure in the Muglad Basin. The results help to resolve long-standing discussion concerning hydrocarbon accumulation of the lower part of Bentiu Formation that lacks horizontal sealing. •Heglig field area in the Muglad Basin has a complex structural configuration.•The complexity reflected in the presence of inversion tectonics in a rift basin dominated by tilted fault blocks.•Inversion tectonics that occurred during the Santonian times has been supported by seismic reflection, velocity, and source rock data.•The inversion tectonics created four-way dip anticline structure that does not rely on a horizontal seal.•Oil entrapment in the Lower Bentiu reservoir that requires a horizontal seal is attributed to the inversion tectonics.