Basin Modeling as a Tool for Research of Regional Oil and Gas Generation Processes and the Possibility of Replacement of Oil and Gas Riches Illustrated through Traygorodsko-Kondakovskoye Oil Field

Abstract

The article presents the results of two-year of research aimed at replenishing the resource and raw material base of the northwestern part of the Tomsk region. The practical application possibilities of basin modeling at the prospecting and exploratory stages of geological study of the subsurface are illustrated. The research was divided into two phases. The first of them has sub-regional coverage and includes an area of 25,000 km2 bounded by the Chkalovsky oil and gas condensate field in the southeast and the administrative boundaries of Tomsk Oblast in the northwest. The section is confined to the Alexandrovsky arch, covers part of the Koltogorsko-Nyurolsky chute and the eastern periclinal of the Nizhnevartovsky arch. At the first stage, a three-dimensional model of oil-and-gas bearing basin formation was created, the tasks of which were to replenish the history of generation and formation of ideas about the ways of hydrocarbon migration. The basin submergence has been reconstructed here and the thermal flow history has been restored. The uneven intensity of heat flow at the bottom of the sedimentary cover over the area is explained by tectonic processes and is complicated by a massive granitoid intrusion. In JSC "Tomsk Petroleum institute", the knowledge base of geochemical features of oil-and-gas source rocks and oils of Western Siberia was formed for years, which allowed to use their own kinetic spectra for the surveyed region. To calibrate the paleotemperatures, both the optical characteristics of vitrinite coals and the indicators of the geochemical properties of organic matter of the Bazhenov formation (4/1 MDBT and Tmax) were used. As a result, the conclusion about the presence of two generation centers of different nature was made, the time and volume of oil generation by organic matter of the Bazhenov formation were predicted. Next, the modeling parameters of hydrocarbon migration and accumulation are described. Modeling shows that the primary migration occurs due to the emergence of abnormally high pore pressure during the generation of hydrocarbons and fluid autofracture of the oil and gas source rock. The results of calculations of secondary migration by two different methods are compared. Despite a number of limitations, the results obtained show a fairly high convergence to real data. At the second stage, on the basis of the regional (parent) model a local daughter model of the formation of the Traygorodsko-Kondakovskoye field within the area of 480 km2 covered by 3D seismic exploration was plotted. The rationale for the necessity and description of the results of additional special geochemical studies of fluids and oil source rock, carried out before starting to build a detailed model of the local stage, is given. The article outlines the basic parameters and gives the differences between the local model and the parent model. Conclusions are made about the possibility of assessing the conductive properties of fault in the formation of deposits. The prediction of trap saturation and resource potential assessment is the result, the achievement of which reduced the risks of geological exploration and formed the recommendations for further geological study of the subsurface.