Geodynamic regime and prospects for oil and gas potential in the South Caspian Basin

Abstract

The article considers the geodynamic regime of the South Caspian depression, de- fines the directions of compressive stresses, the role of the latter in changing the thickness of sedimentary formation complexes, in the formation of local uplifts and their complication by faults and mud volcanism. The purpose of the study is to research the geodynamic regime and determine the oil and gas content of the South Caspian depression. The article reflects the features of studying the zone of pseudosub- duction in the South Caspian depression and the analysis of the obtained results of the prospects of oil and gas potential from the point of view of the influence of modern geodynamic processes. The study of the intensity of the formation of sedimentary facies complexes in the South Caspian depression and the features of the intensity of sedimentation allows us to distinguish 4 stages in different time intervals. According to the analysis of the available data, an inverse relationship has been established between the duration of each stage and the thickness of deposits accumulated during this period of time. In other words, the shorter the duration of the stage, the greater the thickness of the formed deposits. It was found out that this is the result of geodynamic processes occurring within the Southern Caspian Sea and in the adjacent areas, and due to the prevailing geodynamic conditions, the uncompensated deflection regime prevailing for the bottom of the South Caspian Basin had a direct impact on the process of oil and gas formation in its sedimentary cover. The depths of the boundary isotherms of catagenesis and the zone of oil and gas formation were determined in order to determine the state of each sedimentary-facies complex in the vertical zonality of oil and gas formation. It was found that in the western part of the South Caspian Basin, the lower boundary of the protocatagenesis zone is 3 km, the isotherm of the lower boundary of the oil window corresponding to 1500 C is located at a depth of 11-12 km, and the depth of the main gas formation zone corresponding to 2500 C is 18-19 km. The presented analysis of the features of oil and gas formation makes it possible to predict the formation of liquid hydrocarbon deposits at depths corresponding to the oil formation zone.