Multiscale Integration of Gravity and Magnetic Methods for Hydrocarbon Exploration in Frontier Basins: A Methodological Framework and Case Study from the Lower Benue Trough, Nigeria

Abstract

Integrated interpretation of gravity and magnetic data is particularly valuable in frontier sedimentary basins where seismic coverage is sparse, uneven, or insufficient to resolve basin-scale basement architecture. This paper develops a multiscale framework for combining gravity and aeromagnetic observations from regional to local scales, with emphasis on the complementary sensitivity of the two methods to density and magnetic-susceptibility contrasts. The framework combines regional–residual separation, upward continuation, reduction to the magnetic equator, derivative-based edge detection, analytical signal analysis, source parameter imaging, and spectral depth estimation. Integration is organized at three levels: qualitative geological correlation, semi-quantitative structural/depth interpretation, and quantitative comparison of depth and anomaly metrics. A case example from parts of the Lower Benue Trough, southeastern Nigeria, is used to demonstrate the workflow. The case-study data comprise legacy ground gravity observations, satellite-derived gravity information, and high-resolution aeromagnetic data from the Nigerian Geological Survey Agency. Thesis-derived results show marked spatial variation in basement-related source depths: shallow magnetic-source depths of approximately 0.3–3.7 km, magnetic centroid depths of approximately 1.84–5.95 km, gravity-derived deep-source depths of approximately 5.0–6.2 km, and gravity Source Parameter Imaging depths of approximately 2.4–2.9 km. The integrated maps indicate a structurally heterogeneous basin with major NE–SW trends and subordinate NW–SE and N–S structural orientations. The framework demonstrates how potential-field products can be combined to reduce interpretive ambiguity, distinguish basin-scale architecture from local structures, and generate testable hypotheses for petroleum-system analysis. The case study is presented as an application of the framework rather than as a new dataset or independent inversion study.

Keywords: gravity; aeromagnetics; multiscale analysis; potential fields; basement depth; structural interpretation; Lower Benue Trough; hydrocarbon exploration