Imaging of Tertiary Turbidite Channel offshore Angola, West Africa

Abstract

The Tertiary of Angola reveals complex submarine channel that mainly are controlled by salt tectonics. These deep water channels are sinuous, and using 3D seismic from block 34, offshore West Africa, it was possible to image twelve channels, including an amalgamated channel that seems to have been formed by the amalgamation of two parallel channels.

The methodology for this thesis was to try to find out channels using time-slices from seismic cube and then compare this with seismic cross-sections, and in doing that it was possible to image twelve channels. An important characteristic of Tertiary channels offshore Angola are that, they are easily recognised in time slice, because of their sinuosity, point bars, lateral migration and vertical aggradation. In cross-section it was possible as well to see shingled reflections, lateral migration and vertical aggradation. Channels dimensions range from 8-11 km long and 1 km wide. Some channel have well developed levees, with < 2 km wide, Channel from Miocene have mostly an aggradational architecture; while some channel from Oligocene they have an erosional architecture.

Most of the channels from block 34 entered in the block from East and North and channels are more abundant in the central part of the block. With our methodology it was not possible to identify channels from the southern part of the block. The presented maps from block 34, are clearly showing the distribution of the twelve channels in the block 34.