Investigation of the Gravity Anomalies within Brass and Environs, Niger Delta Area, Nigeria: Implications for Hydrocarbon Prospectivity

¹Egwuonwu, Gabriel Ndubuisi*, ²Ibe, Stephen Onyejiuwaka, ¹Ejike, Kingsley Nnaemeka, ³Orji, Obinwa, and ⁴Ombu, Righteous Emmanuel
¹Department of Physics and Industrial Physics, Nnamdi Azikiwe University, Awka, Anambra State, Nigeria
²Department of Physics, Federal University Otuoke, Bayelsa State, Nigeria.
³Department of Physics, Clifford University, Owerrinta, Nigeria.
⁴Department of Physics with Electronics, Federal Polytechnic Ekowe, Bayelsa State.
*Corresponding Author’s
DOI: https://doi.org/10.51584/IJRIAS.2023.8606

Received: 24 May 2023; Accepted: 01 June 2023; Published: 03 July 2023

Abstract: The airborne gravity data over Brass Area and environs, Niger Delta Area, Nigeria were processed and interpreted in order to delineate the sedimentary thickness within the basin and map out places with the potentials for hydrocarbon formation, accumulation and migration. The geological structures, depths and structural trends within the area were investigated using Total Horizontal Gradient, Tilt Derivative, Analytical Signal Filters and Euler Deconvolution techniques. The results from Euler depths showed that the sedimentary thickness and structural depths within the area range from about 1.6 to over 17.4 km. The area predominantly has NE-SW structural trend with minor NW-SE trend. The sediment thickness and structural endowment of the area prompted the classification of Egeregere, Brass, Spiff Town, Kirikakiri Areas in the northern and the southern parts of the area as zones of very viable potentials for hydrocarbon generation, accumulation and migration.

Keywords: Brass Area, Sedimentary Thickness, Structural Complexity, Structural Faults, Intrusive Activities, Hydrocarbon potential.

I. Introduction

Geoscientists have described gravity method as the foundation of Geophysics (Osazuwa, 2006; Ibe and Anekwe, 2016). Density is an important parameter for the determination of gravity anomalies. The accuracy of Bouguer anomalies and their interpretation depend greatly on the assumed density of rocks or more accurately the density differences of rocks . It is known that gravity anomalies result from the differences in densities, or density contrasts between rock bodies and their surroundings (Egwuonwu et al., 2021). Gravity generally relates to other geophysics disciplines, directly or indirectly. For example, both magnetics and gravity are potential fields, derivable from the inverse square law and there is an empirical relationship between them popularly known as the Poisson relation. This relation makes it possible to determine the pseudo field of one from the measured field of the other. In oil and gas Industry seismic remains the primary method for exploring hydrocarbon prospects. However, it is rational to implement inexpensive geophysical exploration methods before seismic detailing (Telford et al., 1990). The use of magnetic and/or gravity techniques for basin delineation at a regional scale, especially in hydrocarbon exploration, is well-known (Osazuwa, 2006; Ibe and Anekwe, 2016). Hydrocarbon exploration applies gravity method in detecting faults and igneous intrusions, forming structural traps for hydrocarbon. Magnetics is commonly used with gravity as low-cost methods for mapping out structures and delineating the sediment thickness during the beginning phases of exploration. Evaluation of structural systems aims to target structural traps and sediment thickness to assess the maturity of the sediments within the target basin.

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