Influence of geotemperature conditions on the oil and gas potential of the South Caspian depression (the case of the Lower Kura depression and Baku archipelago)
Authors: Nasibova Gultar J. , Mukhtarova Khuraman Z. 
Published: March 2024

In the article, the oil and gas potential of the deep-lying sediments of the Lower Received in revised form 13.08.2023; Kura depression and the Baku archipelago, which are geostructural elements of the South Accepted 13.11.2023 Caspian depression, are investigated according to the geotemperature conditions. The main aim of the research is identifying the oil-gas «windows» in the 22-24 km thick sedimentary rock complex of the South Caspian depression based on the geothermal factor. Using temperature values measured at different depth sections in different structures of the Lower Kura depression and Baku archipelago, temperature distribution maps of the area and a graph of changing temperature by depth were constructed. According to the geothermal maps constructed for the Lower Kura depression, a relatively high temperature value is observed in the north-west part of the area. This anomalous value is related to the location of active, periodically erupting mud volcanoes, which play an important role in temperature distribution, as well as local uplifts, which are more complicated by tectonic landslides and upthrusts. At great depths (5,500-6,500 m) within the research region, almost everywhere, anomalously high pore and reservoir pressures are observed, which create the conditions for the manifestation of tectonic-physical processes and the generation of great energy affecting the oil and gas potential of the area. In all the geotemperature maps constructed for different depth intervals in the Baku archipelago, high temperature values are observed in the north zone where the Sangachal-deniz-Duvanni-deniz-Khara-Zira island and Alat-deniz structures are located. This is due to the complication of uplifts by active mud volcanoes, which play an important role in the formation of local heat sources. The Khara-Zira island mud volcano, the largest in the Baku archipelago, is also located here. Based on the analysis of the temperature values in the research areas, a decrease in the temperature values is observed due to increase in the thickness and the clay content of the sedimentary layer in the direction from the Lower Kura depression to the South Caspian basin. The temperature is 990C at 5,000 m in the Lower Kura depression, 900C in the Baku archipelago. So, a decrease in temperature is characteristics for all depths. The analysis of the compiled graphs shows that the top of the main zone of oil formation in the Lower Kura depression starts at a depth of 2,000-2,500 m, and the lower limit is located at a depth of about 9,000 m (1500 C). The top of the main zone of oil formation in the Baku archipelago starts at a depth of 3,000 m, and the lower limit is located at a depth of 9,000-11,000 m. So, it shows that as the oil and gas formation sources the potential oil source rocks in the Lower Kura depression and the Baku archipelago at the depth range from 2,000-2,500 m to 8,000-11,000 m can produce industrially important oil and gas.