Evaluation of hydrocarbon potential of Lower Kura on the basis of basin modeling technologies
Asgarova Roksana Akbar
2521.01 – Geology, prospecting and exploration of oil and gas fields
The researches done for Lower Kura Depression and models plotted allowed to conclude such as follows:
1. The modeling analysis of the evolution of geothermal field of Lower Kura depression allowed revealing that geothermal regime of the regional sedimentary cover is controlled by the lithofacial composition of the cross-section of the various regions, degree of the tectonic dislocation, mobility condition of the thermal underground waters, and formed by the conductive component of the summarized heat flow.
2. The modelling of geobar condition of Lower Kura depression allows to conclude that abnormal high formational pressure and abnormal high pore pressure have syngenetic generatingnature at the expense of own internal energetic resources of the sedimentary complexes, and epigenetic nature which is linked with the injection into restricted confinedly elastic capacity properties of the incoming high pumping agents. The whole crosssection of the reservoir is the powerful unique geofluid dynamic system controlled by the lithology parameters and disjunctive tectonics. In the depression zone, the geobar conditions of the high thickness sedimentary complexes are characterized by the local abnormal high pore and formational pressure of Paleogene throughout structure, and this, in turn, defines the migration geodynamic and hydrocarbon accumulation.
3. As a result of the analysis of two-dimensional models for the Lower Kura Depression, the main distribution of the oil and gas generation zone, the resupmtion of the rock formation processes showed that at the hydrocarbon systemborders, there are a number of particular oil and gas formation focal zones: Oligocene-Miocene, Eocene, Paleogene, Cretaceous.
4. The hydocarbon generaton focal zones were defined which correspond to the various hypsometric and stratigraphic levels. In the northern part of the region, oil and gas formation windowwas defined in the Miocene-Oligocene (4.5-6.5 km), in the eastern part “oil window” was observed in the Oligocene-Eocene (6-9 km), “gas window” was evident in Eocene-Paleogene (9-13 km), in the western part “oil window” was revealed in the Oligocene-Paleogene (9-12 27 km), and “gas window” was defined in the Paleogene-Cretaceous (12-15 km).
5. In Lower Kura Depression, there clarified the peculiarities of the geologic structure of the natural resources at the analysis of the two- and threedimensional lithofacial, petrophysical modeling, ascertained the regularities of the amendments of the formation collectors in the vertical and horizontal directions. In the structures, located in the northern-eastern part of the depression, the lower part of the relatively large productive layer is sandier content. Sandy strata being present stand out here more clearly. Although such depth corresponds to the existence of Paleogene-Miocene deposits, most presumably these deposits form and generate the hydrocarbon complexes. Southern-westward, Oligocene-Miocene cross-section consists mainly of the sedimentary materials of the clayey facies among which there are rare layers with favorable collector properties.From northern-east to southern-westward, there observed decreasing sandy part from 21.3% to 10.21%, which is linked, most presumably, with the regional subsidence of the Lower Kura Depression towards South Caspian. Mesozoic-Cenozoic sediments of the Depression, which are characterized by the high collector properties, are favorable lithological medium for the collection of the oil and gas conglomeration.
6. Intensive processes of the oil and gas formation occurred in the synclines of Hajigabul, Salyan-Mugan, Kurgala Nava and Shirvan-more. As the time goes on, oil and gas formation processes in the Hajigabul and Salyan-Mugan synclines started in the Early Paleogene and ended in the later of Middle Miocene. However, this process in the Kurgala and Shirvan-more synclines corresponds from the Middle Paleogene to Middle Miocene, but in the Navayi synclines which started in the more ancient time (maybe in the Early of Cretaceous) ended in the Middle Paleogene. Paleogene-Miocene middle stratigraphic interval might be situated in the intensive zone of the oil and gas formation. Paleogene-Eocene deposits entered in the stage of maximum generation in the Hajigabul and Mugan synclines in the Early Paleogene, in the synclines of Kurgala and Shirvan-more – in the Middle Paleogene, and intensive generation of hydrocarbons continues up to the present time. Maykop (Oligocene-Lower Miocene) deposits are completely located in the zone of oil and gas formation and intensive generation of hydrocarbon continues till the IV period, inclusive.
7. Aiming to estimate the oil and gas perspectivity in the deep deposits (Pliocene) of the Productive Layer of the Lower Kura Depression deposits, the plotted models allowed to level their perspectivity. I – high oil and gas perspectivity zone; II – oil and gas perspectivity zone; III – relatively weak oil and gas perspectivity zone; IV – weak oil and gas perspectivity zone