Recognition of the pre-salt regional structure of Kwanza basin, offshore in West Africa, derived from the satellite gravity data and seismic profiles

Abstract

Kwanza basin, located on the west coast of Africa and the east side of the South Atlantic Ocean, has the potential for deep-water oil and gas exploration. Previous studies have shown that the pre-salt system within the area has high potential for oil and gas storage. However, due to the shielding effect of the evaporating salt rock during the Aptian period, the quality of seismic reflection profiles of the pre-salt layers is poor. This means that the pre-salt sequences, the main fault, the scale and distribution pattern of the rift are not clear. To clarify the pre-salt regional structure pattern and further guide pre-salt exploration, we carried out a series of analyses and target processing of seismic and gravity data. Further, combining other available geological and lithology data as well as a tectonic model, we put forward a new understanding of the pre-salt structure of Kwanza basin. The research shows that the Kwanza basin can be divided into three uplift belts below the salt layer, which are distributed in the NW–SE trending direction. The three key profiles illustrate the distribution of uplift and depression in detail. The explained structural highs distributed in the outer Kwanza basin may be related to oil and gas reservoir. This study could provide the geophysical basis for the re-interpretation of the pre-salt seismic sequence, the strategic selection of pre-salt oil and gas and the next exploration deployment.