--> Diversity Analysis of Various Types of Deep Water Channels in Lower Congo Basin, West Africa

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Diversity Analysis of Various Types of Deep Water Channels in Lower Congo Basin, West Africa

Abstract

Large-scale deep water fan is developed in Lower Tertiary strata of Lower Congo Basin, West Africa. Channels are the main sedimentary province for sand body. Based on the difference of curvature, geometry morphology (width and depth), erosion ability (high, middle, weak) and limiting conditions (confined, weak confined, unconfined) among different channels in this area, by using 3D seismic attribute fusion technology and 3D visualization technology, deep water channels can be divided into 5 types: erosional channel, aggradational levee channel, lobe channel, meandering complex channel, and valley-fill complex channel. The erosion ability of erosional channel and aggradational levee channel is much stronger than the others. The average curvature of those two is greater than 1.2. The average width is 150m and the depth is about 30m. They have confined and weakly confined limiting conditions respectively. The lobe channel has the weakest erosion ability with its sandstone distribution thin and wide and is considered as unconfined distributive condition. The scales of meandering complex channel and valley-fill complex channel are relatively large. The average sand content percentage of those two types is about 48%. They are under confined limiting conditions. The distribution proportion of meandering complex channel is relatively high, and that of valley-fill complex channel is lower in the study area. The drilling results show that the factors including limiting conditions, channel development periods, curvature and geometry parameters (the ratio of width to depth) have influence on sandstone distribution of channels. The meandering complex channel is the best type due to the wide sandstone distribution and the most important exploration target.