Lithological-facies structure and history of the development of B5 formation of the Danilovsky license area (Vendian-Cambrian, Eastern Siberia)

In 2004, exploration drilling in the central part of the Nepsko-Botuobinsk anteclise of the Leno-Tunguska oil and gas province of Eastern Siberia at the Danilovsky license area proved the oil content and prospects of the oldest carbonate deposits of the Vendian-Cambrian period. The drilled carbonate complex is characterized by a complex structure and strong variability of structural and textural features in section and laterally. A full cycle of lithological studies, including a description of petrographic sections in combination with X-ray diffraction analysis, and facies analysis of lithological rock types allowed considering the nature of deposits of the productive formation B5 of the Danilovsky horizon. Cyanobacterial communities in the lifetime position were recorded in the section of the formation, confirming the organogenic skeleton nature of the studied deposits. Septal, chamber and clot forms of communities have been recorded. The results of the genetic analysis of geological and geophysical data formed the basis for a detailed lithological and sedimentological characteristic of the section, which allowed recreating the history of development and forming a sedimentation model of the formation. These studies laid in the basis for the petrophysical model of the formation, the planning of exploratory drilling and the introduction of an optimal development system.