Structural interpretation of High-resolution aeromagnetic data over the Dahomey basin, Nigeria: implications for hydrocarbon prospectivity

E M Okoro,C I P Dim,C G Okeugo,K M Onuoha

doi:10.1007/s13202-021-01138-w

Abstract

The renewed quest to boost Nigeria’s dwindling reserves through aggressive search for oil and gas deposits in Cretaceous sedimentary basins has re-ignited the need to re-evaluate the hydrocarbon potentials of the Dahomey Basin. Aeromagnetic data are a low-cost geophysical tool deployed in mapping regional basement structures and determination of basement depths and sedimentary thickness in frontier basin exploration. In this study, high-resolution aeromagnetic (HRAM) data covering the Dahomey Basin Nigeria have been interpreted to map the basement structural configuration and to identify mini-basins favorable for hydrocarbon prospectivity. The total magnetic intensity grid was reduced to the equator (RTE) and edge detection filters including first vertical derivative (FVD), total horizontal derivative (THDR), tilt derivative (TDR) and total horizontal derivative of upward continuation (THDR_UC)) were applied to the RTE grid to locate the edges and contacts of geological structures in the basin. Depth to magnetic sources were estimated using the source parameter imaging (SPI) method. Data interpretation results revealed shallow and deep-seated linear features trending in the NNE-SSW, NE-SW, NW-SE and WNW-ESE directions. The SPI map showed a rugged basement topography which depicted a horst-graben architecture on 2D forward models along some selected profiles. Two mini-basins ranging in basement depths between 4.5 – 6.3km were mapped offshore of the study area. It appears the offshore Dahomey Basin holds greater promises for hydrocarbon occurrence due to the presence of thicker succession of sedimentary deposits in the identified mini-basins.

Highlights

The Dahomey Basin is located within the Gulf of Guinea, West Africa and covers the western coast of Nigeria on latitude 6 ° 00’ – 7° 00’N and longitude 2 ° 30’ – 5 ° 00’E (Fig. 1)
Understanding the structural configuration of the basin in the context of the tectonic development of the Gulf of Guinea will be critical in providing insight into the controls on the distribution of mini-basins favorable for future hydrocarbon prospectivity in the basin
By mapping the structure and basement depth in the Dahomey Basin from the interpretation of high-resolution aeromagnetic data, the structural pattern will shed light on the prevalent tectonostress regimes responsible for the basin evolution and enable proper understanding of the dominant role the basement architecture played in the development of petroleum systems elements in the basin (Fairhead et al 2012)

Summary

Introduction

The Dahomey Basin is located within the Gulf of Guinea, West Africa and covers the western coast of Nigeria on latitude 6 ° 00’ – 7° 00’N and longitude 2 ° 30’ – 5 ° 00’E (Fig. 1). The basin has become an important exploration target for the petroleum industry following the Federal Government’s renewed quest to shore-up Nigeria’s dwindling reserves through intensive search for conventional oil and gas deposits in frontier inland and coastal basins of Cretaceous age This has resuscitated the need to critically interrogate the existing dataset in the Dahomey Basin and other. By mapping the structure and basement depth in the Dahomey Basin from the interpretation of high-resolution aeromagnetic data, the structural pattern will shed light on the prevalent tectonostress regimes responsible for the basin evolution and enable proper understanding of the dominant role the basement architecture played in the development of petroleum systems elements in the basin (Fairhead et al 2012) Such regional geophysical study is needed to high-grade target areas within the basin for future concentration of exploration efforts

Methods

Results

Conclusion