Prediction of hydrocarbon accumulation zones in Osinsky horizon within Baikitsky anteclise

The authors describe the local object identified in Lower Cambrian deposits using deep drilling data and 3D CDP seismic data. The object is a linear narrow roughly NS trending zone of the Osinsky horizon salinization. It is recommended that the time anomaly formed by this zone should be taken into account in structural imaging. Reef-like objects delimiting this salinization zone along its whole length are identified in 3D CDP time sections and horizontal slices of seismic attribute cubes. Two of the most likely models of this zone formation have been proposed to explain the presence of an anomalous stagnant area in the paleobasin where sedimentation occurred. The common elements of the proposed models are presence of a large fault and organic buildups in the role of impermeable barriers. It is shown that the simplest model assuming existence of graben is not supported by drilling since there is no increase in sediment thicknesses in the volume of the Osinsky horizon within the salinization zone. The detailed substantiation of organic buildups consequential evolution from mud mounds to reef-like buildups around them is given, which explains the possibility of stagnant conditions formation without formation of a graben. It is suggested about the shielding role of this zone and the possibility to discover hydrocarbon deposits to the east, which is confirmed by results of drilling