Geomagnetic evaluation of hydrocarbon prospectivity of the Nigerian sector of the Chad Basin

Abstract

The interpretation of the geomagnetic data covering the Nigerian Sector of the hydrocarbon elusive Chad Basin has been carried out with the aim of evaluating its hydrocarbon prospectivity. The geomagnetic data was subjected to transformation and enhancement techniques such as reduction to the equator, band-pass filtering, analytic signal, pseudogravity, Source Parameter Imaging (SPI), and Euler deconvolution (ED). The 2-D forward modeling was done using the GM-SYS™ software. The results revealed two subbasins, separated by basement high, where the thickness of sedimentary succession of source rocks, reservoirs, and seals attained about 5 km. Two sets of laterally persistent NE-SW and NW-SE fracture systems capable of forming migratory routes were identified within the study area. Euler solutions show basement fractures that propagate through the sedimentary column at 1000 to 5000 m. Characteristic alternation of positive and negative pseudogravity anomalies exposed basement configuration to be of horst and graben architecture. Constructed models revealed drape anticlines that could act as structural traps in the event of hydrocarbon generation. Analytic signal anomalies indicative of igneous intrusive were mapped within the subbasins. This study concluded that elements that favour hydrocarbon occurrence are present in the Chad Basin and was therefore considered to be of high hydrocarbon prospectivity provided the occurrence and timing of the igneous intrusions had not adversely affected hydrocarbon accumulation.