Modeling Crustal Structures of Southern Nigeria Basins from Aeromagnetic Data: Implication on Hydrocarbon Prospectivity

Modeling Crustal Structures of Southern Nigeria Basins from Aeromagnetic Data: Implication on Hydrocarbon Prospectivity

Southern Nigeria has major and minor sedimentary basins. This study covers parts of 5 sedimentary basins in southern Nigeria, this includes the Niger Delta, Benue Trough, Calabar Flank, Mamfebasin and  Lower  Benue  Trough. Aeromagnetic data  has  been  used  by  many  authors  worldwide  in evaluation  of  subsurface  basin  configuration.  This  study  covers  parts  of  five  basins  (Niger  Delta, Calabar Flank, Anambra Basin, Mamfe Basin, and Lower Benue Trough) in Nigeria. The study utilized twenty aeromagnetic maps on a scale of 1:100,000. The maps were digitized manually along flight lines and a total of 16,689 data points obtained. The data was processed using computer techniques including map merging, reduction to pole, polynomial and power spectrum filtering for residual and regional  anomaly  separation,  and forward  and  inverse  2.5D  Saki  modeling.  Results  obtained  from power spectrum depth analysis indicate depth to magnetic sources vis –a –vis sediment thickness  from the Niger Delta area (2.75 km -3.75 km), Anambra basin (1.5 km –2.6 km), Calabar Flank (1.3 km –2.3 km), Mamfe basin (2.0 km –3.4 km), and Lower Benue Trough (1.5 km –3.2 km). Also, depth to basement results from forward and inverse modeling indicate the Niger Delta has thickness of sediments ranging between 1.0 km-8.0 km, Anambra basin (1.4 km –2.7 km), Calabar Flank (0.8 km-2.5 km), Mamfe Basin (1.0 km –2.7 km), and Lower Benue Trough (1.4 km –2.7 km). Also, results from modeled number of intrusives indicate that the Calabar Flank has five intrusives, Niger Delta  has four  intrusives,  Mamfe  basin  has  six  intrusives,  Anambra  basin  has  five  intrusives,  and Lower Benue Trough has four intrusives. The implications of the increased number of intrusives are that generated hydrocarbons might be converted to gas, this is more likely in areas around Calabar Flank, Mamfe basin and Anambra basins, given the high number of occurrence of intrusives within these  areas.  Whereas  areas  around  the  NigerDelta  and  Lower  Benue  Trough  with  significantly increased depth and lower number of intrusive are less prone to excessive heat from the intrusive and may  produce  more  oil.  The  study  support  further  exploration  activities  within  the  Niger  Delta  and Lower Benue Trough areas. The significance of this study is the wide range appraisal of the basin architecture and configuration of the offshore and inland basins in Southern Nigeria. The Niger Delta basin areas of Portharcourt, Bonny with sediment thickness of about 8.0km and less occurrence of intrusives has the highest hydrocarbons exploration potentials. The Bansara area within the Mamfe basin has  (2.6 km) sediment thickness that could generate hydrocarbons given that another condition is favourable, but the presence of numerous intrusives may make the area prone to excessive heat and  may  produce  more  gas  than  oil.  The  Anambra  basin  and  the  Lower  Benue  Trough  have  a moderate  depth  of  sediments  thickness(2.5km)  and  less  number  of  intrusives,  these  areas  came second to the Niger Delta among the studied basins for good prospects in hydrocarbon exploration investigations.  It  is  concluded  that  this  study  reveals  the  order  of  preference  of  the  choice  of investigating the hydrocarbon prospective potentials of  Southern Nigerian basins using the potential  field magnetic method, it is recommended that other geophysical methods such as gravity, and seismic be used to identify possible hydrocarbon habitats within the  Southern Nigeria Basins.

Read full article: http://bp.bookpi.org/index.php/bpi/catalog/view/37/130/259-1

Editor 251News

leave a comment

Create Account



Log In Your Account