Characteristics of gravity and magnetic anomalies and their petroleum geological significance in the Yingen-Ejinaqi Basin, Inner Mongolia, China

Abstract This research aims to explore petroleum resource distribution characteristics in the Yingen-Ejinaqi Basin and provide a basis for assessing the prospect of petroleum potential in the region. Based on recent and previous gravity and aeromagnetic data obtained in the basin, anomalies including regional and residual gravity and magnetic anomalies, various derivative anomalies, and anomalies in structure-enhancing filtering were determined using multiple techniques. By analysing gravity, magnetic, and seismic anomaly characteristics of existing typical oil and gas wells, the petroleum resource distribution was studied by combining such data with exploration results arising from wells where oil and gas have been discovered. The research shows that the distribution ranges of the sags revealed by seismic profiles correspond to those of negative residual gravity anomalies; the distribution ranges of rock masses identified in the sags along the seismic profiles show some correspondence to the positive residual magnetic anomalies. Analysis indicates that various sags corresponding to areas where negative residual gravity anomalies appear in the north and south of the basin are the primary and secondary favourable areas for oil and gas exploration in Mesozoic–Upper Palaeozoic strata. Therefore, breakthroughs in oil and gas exploration should be made by focusing on these sags in the region. The positive residual magnetic anomalies in the basin can reflect the distribution of concealed rocks in the region, while concealed rocks in sags are an important area for oil and gas exploration in igneous rocks in the basin.