Interactions between Submarine Channels and Salt Structures: Examples from the Lower Congo Basin

Key words: 
• salt structures /
• deepwater channel /
• deflection /
• interactions /
• Lower Congo Basin

Abstract: Submarine channels as the main reservoir of deep-water oil and gas is an important goal of deep-water oil and gas exploration in passive continental margin basin. The multi-periodic tectonic activities of the salt structures result in being not clear about the distribution law of channel sand body in the Lower Congo Basin. The research on interactions between submarine channels and salt structures contributes to predict the distribution of channel sand body. In salt structures and submarine channels widely developed area of Lower Congo Basin, based on three-dimensional seismic data, the interactions between salt structures and submarine channels are analyzed and build the interaction model of salt structures related to submarine channels is established. Six submarine channels-salt structures interactions can be defined, respectively, as confinement, diversion, blocking, corrosion, deflection, and erosion. The interactions between channels and salt structures may be dictated by the timing of salt structural activities related to the channel development and the erosional power of the channels. Salt structures which predate the channel development and the weak erosional power of the flows within the submarine channels cause channels to take a moderate confinement or diversion. When the erosional power of the flows is strong enough, submarine channels can continue to incise across the salt structures. The large-scale salt structures can block the submarine channels causing reflection of turbidity alone the submarine channel, and lobes develop. Activities of the salt structures which are consistent with channels development may cause deflection. Overlying submarine channels which predate salt structures may be eroded.