DEPOSITIONAL CHARACTERISTICS OF MIOCENE DEEPWATER CHANNEL DEPOSITS IN BLOCK A OF LOWER CONGO BASIN

The distributary channels of gravity flows are typical deepwater depositional elements well developed in the Miocene of the Lower Congo Basin. Advanced Geophysical technology, such as 3D ESP coherence time slices, RMS amplitude and 3D visualization, have been used to identify the deep-water meandering channels. The internal filling structures of the complex channel sand body are discussed and described in this paper. The channel sand bodies developed in the study area were traced through geologic anomaly with 3D visualization technique, and the plane distribution and reservoir characters were revealed. The high sinuous gravity flow distributary channels could be classified into 2 types, i.e. erosional and erosional/aggradational channel complexes, according to the filling pattern of the sediments. Large-scale erosional channel with multiphase fillings are composed of rotational sliding blocks, debris flow deposits, stacked channel and channel-levee deposits, which were recognized with 3D visualization. Their seismic reflection characteristics and logging responses were studied as well in details.