Structural Characteristics And Its Control Over Hydrocarbon In Bongor Basin

Bongor Basin which is controlled by Central African Strike-slip Zone is located in the southwest of Chad Republic.As the exploration result shows,Bongor basin is rich in oil and it's the most important basin in Block H.So far,three reservoir combinations have been ascertained: Burried hill reservoirs,Lower reservoir combination(M-P)and Upper reservoir combination(R-K).Burried hill reservoirs and Lower reservoir combination are the main exploration targets.Based on the geological study,the author conducts the study of tectonic geometry and Structural Kinematic by using the extensional tectonics theory and methods.Characteristic of faults,the tectonic evolution,structure of the basin,tectonic elements study,structural styles,and the controlling of structures to sedimentation are completed by using Landmark and Geoeast interpretation systems.Based on the study of regional tectonic background and tectonic evolution in Bongor Basin,the following items have been ascertained: three stages of depression and two stages of structural inversion occurred in Bongor Basin;most of the hydrocarbon bearing structures were formed in early Cretaceous and they were reformed in Santonian(late Cretaceous);Stable depression is the character of Paleogene period,and the structural inversion in Oligocene was weak.Extensional structures,strike-slip structures and inverted structures are found in Bongor Basin as a result of tenso-shear stresses and structural inversion.The structures also can be classified as basement-involved structures and detachment-type structures.Two regional unconformities and three structural layers can be identified based on the tectonic evolution and the characteristics of faults.The inverted structures are in close relationship with discovered oil and gas reservoirs.Tectonic activities play important roles in the formation of buried hills and distribution of reservoirs.