Pre-salt regional structure and its control for hydrocarbon accumulation in Lower Congo Basin from seismic and gravity data

Abstract

In the present work, we utilize the processing and interpretation of both seismic and gravity data to clarify pre-salt regional structure pattern and further guide pre-salt exploration in Lower Congo Basin. Combining other available geologic and lithology data sets as well as a tectonic model, we present a new understanding of the pre-salt uplift and depression pattern of Lower Congo Basin. The results show a clear E-W distribution of the first-class structural units, namely, the inner rift zone, central uplift zone and outer rift zone, where the latter two parts are separated by the Atlantic hinge zone. The outer rift zone is characterized by a "two convex and three concave" high and depression pattern. The patterns of the pre-salt structure control the distribution of source rocks, reservoir and cap rock types, and also affect the combination and model of hydrocarbon accumulation. The key exploration area can be placed in the shallow water area on the land side of both the inner rift zone and the outer rift zone. The favorable exploration targets should be focused on fault-controlled blocks of the structural high horst. This study can provide the geophysical support for a new interpretation of the pre-salt seismic sequence, the strategic selection of pre-salt hydrocarbon and the next exploration deployment.