Lithological features of forming paleozoic collectors of the Ledyansk uplift (North Tunguska oil-and-gas area)

Abstract

The relevance of research is caused by the need to study and search oil and gas fields in the Arctic regions of Russia. As the exploration drilling of these areas is very low, the more detailed study of previously drilled wells is required for successful exploration. The main aim of the study is to determine the influence of sedimentation and post-sedimentation factors on formation of the void space of different rock types and to define the levels of potential reservoirs in the Paleozoic section of the Ledyansk uplift. Objects of researches are Paleozoic sediments that were opened by Ledyansk wells in the north of the North Tunguska NGO. The methods used in the study: construction of sections of the Paleozoic sediments on the basis of detailed core descriptions, results of GIS (Well logging) and paleontological research; petrographic study of the main types of rocks involved in the structure of the section; genetic analysis of different rock types and clarification of the conditions of their sedimentation; study of the void space of rocks in cores and thin sections; determination of relationship between lithological characteristics and reservoir properties of the Paleozoic rocks. The results. The authors identified the composition, structure and depositional environment of the Paleozoic sediments, exposed to Ledyansk uplift. The influence of sedimentation and post-sedimentation factors were identified on the formation of reservoirs. It was determined that the highest rates of porosity and permeability are observed in the carbonate rocks of the Silurian reef where leaching has influenced most intensively on rocks and in the Ordovician and Carboniferous sandstones with good primary porosity.

Keywords

• lithology
• North Tunguska oil-and-gas area
• Ledyansk uplift
• Paleozoic sediments