The Gullebi Field lies in the southwestern part of Concession NC7A in the central Ghadames Basin of Libya. The field is characterized by a northeast-southwest trending reverse fault named the Gullebi Fault. The fault extends for about 45 km and is the conduit for the main hydrocarbon accumulation of the Devonian reservoirs.

Based on available seismic data and other geophysical methods that were used in the past for hydrocarbon exploration in the field, there a evidence of significant structural complexity—a radial rim faulting system with a deep depression (ranging from 500 to 1000 ft [152 to 305 m] deep) surrounding a central domal structure. The total width of the anomaly is about 42,651 ft (13 km) in diameter, while the radius of the dome is about 9843 ft (3 km).

To investigate the structural complexities of this anomaly, the Arabian Gulf Oil Company (AGOCO) conducted a new airborne gravity and magnetic survey over the entire area of the NC7A concession adding to the existing seismic data within the concession. Based on the results of all geophysical methods used for this investigation, two hypotheses were established to identify the origin of this anomaly. The first cause could be the possibility of an igneous or volcanic intrusion that originated from the basement. The second theory posits that the anomaly was generated by possible meteorite impact that created synclinal rims around the domal structure. In this paper, we present the geophysical assessment of seismic, gravity, and magnetic analyses and mapping conducted in the area to better evaluate the geological interpretations.