Classification of turbidite channels of the Lower Cretaceous Clinoform complex in West Siberia

Research subject. Turbidite channels of the Achimov formation (Ryazanian-Hauterivian) which occur at the base of the Lower Cretaceous complex of West Siberia. Aim. Identify various types of distribution and feeding turbidite channels, effect on the morphology of underwater fans in order to predict reservoir rocks. Materials and methods. To interpret facies and classify channels within the Achimov Formation, a complex of core, well log and 3D seismic data on ten West Siberian sites was used. The interpretation and classification effort included the lithofacies, ichnological, electrofacies, sequence-stratigraphic and 3D seismic geomorphological analyses. Results. The diagnostic features of turbidite channels, their classification based on channel shape and filling, as well as the effect on the morphology of deep-sea fans and the distribution of sand deposits are presented. Conclusions. Four morphological types of underwater channels have been identified in the Achimov formation of Western Siberia: Erosive; 2) Meandering with an accretion complex without aggradation; 3) Aggrading; 4) Hybrid (mixed). The lateral and time-dependent transformation of the channels has been established. It was noticed that, due to avulsion, most of the deep-sea meandering channels tend to migrate to the left, towards the underwater slope by the effect of the Coriolis force and contour currents, and form fans with left-sided asymmetry. The straightened channels with poor levees form radial fans with high content of sandstones within the cross-section.