Lithofacies characteristics and oil-gas content of Eocene sediments of the Kura-Gabirri interfluve oil-gas-bearing region

This paper lays the foundation for the development of a well sequence stratigraphic framework and contributes to a better understanding of potential hydrocarbon occurrence in the Kura-Gabirri interfluve oil-gas-bearing region. Eocene sediments, which are considered promising in terms of oil and gas, have a complex structure, and here they are mainly characterized by monoclinal bedding of the layers. Against the background of their regional monoclinal bedding, a number of local structural forms with small amplitudes are distinguished. The section of Eocene sediments has been uncovered in full thickness in various areas of the oil-gas-bearing region. In other exploration areas, the Upper Eocene sediments, and sometimes Middle and partially Lower Eocene sediments have been uncovered by drilling of deep parametric and exploratory wells. Data from the drilled wells show that the section of Eocene sediments in the Kura-Gabirri interfluve oil-gas-bearing region is divided into three sections: Lower, Middle, Upper. All three sections differ from each other in terms of lithological characteristics, fauna, and oil and gas content. Distribution maps of Eocene sediments have been compiled and analyzed. For solving the problem, a number of computer programs (for example, Surfer, Petrel) have been used. In the Kura-Gabirri interfluve oil-gas-bearing region, two lithofacies zones are distinguished – southern clayey-sandy and northern terrigenous-carbonate. Along the Kura-Gabirri interfluve oil-gas-bearing region, Lower Eocene sediments are concentrated in the southwest and northwest of the region, Middle Eocene sediments are concentrated in the north and more in the center of the area, and Upper Eocene sediments are concentrated in the southwest, northeast and east directions. When analyzing the section of Eocene sediments , it was determined that the section of the Lower Eocene consists mainly of clays, that is, the percentage of clay is high, varying between 90-95%. The Middle Eocene section consists mainly of tuff-sandstone, carbonate rocks , that is , the section is mainly composed of reservoir rocks. Tuffogenic rocks wedge updip of the layers, forming lithological traps, and the oil and gas content of the region is related to these traps. The Upper Eocene is composed mainly of terrigenous materials in clayey facies. It may serve as a favorable seal for the accumulation of hydrocarbons.