Estimation of Geothermal Gradient and Curie Point Depth for Delineating Hydrocarbon Potentials Zones Over Southern Bida Basin, Northwestern Nigeria

Abstract

Nine aeromagnetic maps (namely, sheets: 204, 205, 206, 225, 226, 227, 245, 246 and 247) over the Southern Bida Basin have been assembled and interpreted in order to analyze the hydrocarbon potentials of the basin using spectral analysis method. The result of qualitative interpretation revealed that the area is intensely faulted with major faults trending East-West (E-W) and minor ones Northeast-Southwest (NE-SW) directions using visual inspection of the magnetic anomalies and first vertical derivative maps. Spectral analysis results revealed two depth sources in the area namely; the shallower sources which range from 0.45 to 1.49km while the deeper ones which range from 1.81 to 3.24km. The result of the analysis also shows that depths to the centroid and magnetic bodies (sedimentary thicknesses) range from 9.09 to 16.84 km and 0.5 to 3.2 km respectively. The average depth to the Curie isotherm in the area is 24.76 km. The result also show that the Curie temperature isotherm within the basin is not a horizontal level surface, but is undulating, and the geothermal gradients associated with it range between 18.82 and 32.03oC/km. Based on the computed sedimentary thicknesses (2.3 -3.2 km), the geothermal gradient (18.82 and 32.03 oC/km.) and the fractures which serve as migratory pathway for hydrocarbon or hydrothermal fluid, then the possibility of hydrocarbon generation in the southern part of the study area is feasible. All these deductions were reached after due consideration of qualitative and quantitative interpretations supported by geological information of the area.