Abstract
Gravity anomalies in parts of the Niger Delta region, Nigeria, were investigated through the interpretation of aerogarvity data with the objectives to determine the thickness of the sedimentary basin, establish the basement topography, density contrasts and the geological models which will give information about variation of geological structures. Four sheets of digital airborne gravity data were used for the study. Source parameter imaging (SPI), Standard Euler deconvolution and forward and inverse modeling techniques were employed in quantitative interpretation. The Bouguer anomaly of the study area varied from -20.0 to 37.7 mGal, while the residual Bouguer anomaly varied from -19.6 to 25.7 mGal. The SPI gave depth values ranging from -539.7 to -4276.0 m for shallow and deep lying gravity anomalous bodies. The windowed Euler-3D for Bouguer gravity result revealed the depth range of 1355.5 to -1518.1 m for structural index of one; 2384.5 to -3283.2 m for structural index of two and 2426.0 to -5011 m for structural index of three. The forward and inverse modeling gave the density values for the modeled profiles 1, 2, 3, 4 and 5 as 1.820, 2.410, 0.720, 2.310 and 2.100 gcm-3, respectively, with their respective depths of 3872, 4228, 4880, 3560 and 2527 m. The results from this study have shown that the depth to basement and density contrast have influence on the petroleum/hydrocarbon accumulation. Key words: Aerogravity, basement, density contrast, sedimentary.  
Highlights
The gravity survey is a non-destructive geophysical technique that measures difference in the earth’s gravitational field at specific locations
Source parameter imaging (SPI), Standard Euler deconvolution and forward and inverse modeling techniques were employed in quantitative interpretation
The results from this study have shown that the depth to basement and density contrast have influence on the petroleum/hydrocarbon accumulation
Summary
The gravity survey is a non-destructive geophysical technique that measures difference in the earth’s gravitational field at specific locations. It could be ground gravity survey or airborne (aero) gravity survey. The gravity method has been widely used in different applications involving engineering exploration, regional and large scales study of geological structures, where measurements of earth’s gravitational field are used to map subsurface variations in density (Biswas and Sharma, 2016; Biswas et al, 2014a, b; Mandal et al, 2015, 2013). The success of the gravity method depends on the different earth materials having different bulk densities (mass) that produced variations in the measured gravitational field. The gravity method has good depth penetration compared to ground penetration radar, high frequency electromagnetic and dc-resistivity techniques and is not affected by high conductivity values of near-surface clay rich soils (Mickus, 2004)
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