See discussions, stats, and author profiles for this publication at: https://www.researchgate.net/publication/259978523 Complex Petroleum Systems of Sea of Azov - Southern Russia Conference Paper · February 2012 DOI: 10.3997/2214-4609.20143892 CITATIONS READS 0 238 3 authors, including: Elena Lavrenova Darko Spahić SC "ASAP" Geological Survey of Serbia 19 PUBLICATIONS 47 CITATIONS 37 PUBLICATIONS 67 CITATIONS SEE PROFILE Some of the authors of this publication are also working on these related projects: The evolution of Paratethys: the lost sea of Central Eurasia View project Paleozoic of West Balkan (Alpine orogen and its basement) View project All content following this page was uploaded by Darko Spahić on 02 February 2014. The user has requested enhancement of the downloaded file. SEE PROFILE B005 Complex Petroleum Systems of Sea of Azov Southern Russia E. Lavrenova (Soyuzmorgeo), D. Spahic* (Schlumberger) & A. Gorbunov (Soyuzmorgeo) SUMMARY Nowadays majority of successful oil and gas discoveries are a result of the sophisticated studies combined with the most recent exploration techniques applied on variety of depositional complexes. One of the proven methods that largely decrease uncertainties in hydrocarbon exploration is numerical petroleum system modeling. By using different petroleum system modeling tools like 1D, 2D & 3D modeling here we investigate complex petroleum system of the southern Russia (Sea of Azov). The subsequent numerical models highlighted a new hydrocarbon system nested within the poorly explored transitional complex of the Sea of Azov. Petroleum Play Assessment Workshop 13-15 February 2012, Malaga, Spain Introduction Nowadays majority of successful oil and gas discoveries are a result of the sophisticated studies combined with the most recent exploration techniques applied on variety of depositional complexes. Each new hydrocarbon discovery is in most cases a consequence of complex exploration strategy that often results in a discovery of new hydrocarbon objects. However, in addition to high exploration costs, sometimes traditional geological exploration methods require undesired additional expenses that often affect overall economic success. Commonly in last decades, in order to reduce risks and avoid any additional expenses, integration of geological databases with subsequent risk assessment has been used by many exploration-production companies. One of the proven methods that largely decrease uncertainties in hydrocarbon exploration is numerical petroleum system modeling. By using different petroleum system modeling tools like 1D, 2D & 3D modeling here we investigate complex petroleum system of the southern Russia (Sea of Azov, Fig.1). The subsequent numerical models disclosed a new hydrocarbon system nested within the poorly explored transitional complex (TC) of the Sea of Azov (Fig 2). The transitional complex of Sea of Azov is a geological object that lies below the well-known Cenozoic productive system (Fig 3). The system is represented by Late Paleozoic and Mesozoic carbonate-clastic system that is crosscut by the extensional deformations. Unfortunately, by using traditional exploration tools, the TC has been only partially explored: poor seismic visualization data, lack of deep exploration wells, scattered geochemical data, etc. Nevertheless, by using petroleum system analysis and associated numerical calculations in PetroMod software we integrated available datasets and subsequently we quantify the hydrocarbon potential of the TC. Results have shown that the investigated Paleozoic-Mesozoic petroleum system has significant hydrocarbon potential. Hydrocarbon saturation of the sediment cover in the Sea of Azov is defined usually by deep exploration well data. Several small gas fields are discovered within the Cenozoic system, for example Strelkovoye, Beysugskoye, Vostochno-Kazantipskoye, etc., as well as the small oilfield - Novoe. Additionally, there are several discoveries among older Eocene deposits: Maikopian play (Morskaya, Nebolshaya, Electrorazvedochnaya, Strelkovaya, Severokazantipskaya fields) and Middle-Upper Miocene system (Obruchevskaya, Oktiabrskaya, Severo-Kerchenskaya, Seismorazvedochnaya, Zapadnobeisugskaya, etc, Fig.4). All identified reservoirs are productive mostly gas-saturated. Preliminary investigations indicated that these gas occurrences are most likely associated to the underlying TC. In order to verify such hypothesis, we investigated maturity and potential of the Tertiary petroleum system (1D basin model of the borehole Oktiabrskaya). . Figure 1 Geographical position of the Sea of Azov including vicinity of mountain Caucasus (modified after Stovba & Stephenson, 2003). Petroleum Play Assessment Workshop 13-15 February 2012, Malaga, Spain Figure 2 There are four main structural elements in the study area: the North Azov Depression, Azov Swell, South Azov Step, IndoloKuban Foredeep. Figure 3 There are two opposite opinion about geological structure of the transitional complex and about its prospects: transitional complex consist of dislocated over matured rocks. Presence of petroleum system is impossible. Transitional complex consist of normal sedimentary rocks, presence of petroleum system is possible (modified after Lavrenova & Kruglyakova, 2010). Petroleum Play Assessment Workshop 13-15 February 2012, Malaga, Spain 1- oil 2- gas 3 - age of reservoir 4 - well 's name Figure 4 Hydrocarbon discoveries across Sea of Azov. Results of the1D model indicated that source rocks in the Cenozoic sediments on the Azov Swell cannot exist (insufficient thermal maturity). In fact, Cenozoic gas shows on the Azov Swell are epigenetic to the investigated sediments. Nevertheless, the investigation confirmed that in addition to a well-known Cenozoic petroleum system in the South-East part of the Sea of Azov, a pod of active source rock (lower Maikopian clay) is located within the Indolo-Kuban foredeep. Oil and gas accumulations that are genetically associated to Kuban foredeep can be expected exclusively in the upper Cenozoic sediments of Indolo-Kuban Fore-deep and South-Azov Step. After extensional tectonic event resulting in accommodation of normal faults, a vertical migration of hydrocarbons was enabled. It seems that hydrocarbons produced within the TC have migrated vertically and subsequently penetrated into the Tertiary sediments deposited along the Azov Swell. The direct TC gas shows that have been detected boreholes Oktiabrskaya and Zapadno-Beysugskaya fields indicated that the only possible explanation of deeper gas accumulations is that they originate from the underlying TC. Furthermore, by using 2D regional model we investigate lateral migration potentials whereby the results clearly showed that there is not enough migration time for hydrocarbons to migrate towards the distant accumulations of the Azov Swell (Fig 5). Finally using the 3D petroleum system modeling we quantified general hydrocarbon potential of the TC. Figure 5 Complex 2D basin modeling used to check later migration possibilities from Idolo-Kuban foredeep to Azov swell. Results are showing that migration could not reach the top of Azovian sweal due to insufficient timing and migration losses (modified after Lavrenova et al., 2011). Petroleum Play Assessment Workshop 13-15 February 2012, Malaga, Spain Conclusions Origin of the gas shows in Cainozoic sediments of the Sea of Azov has been discussed. Using numerical petroleum system modelling is proved that there no source rocks in the sediment cover genetically associated to the gas shows. Therefore it is to conclude that the investigated hydrocarbon system belongs to the hypothetical petroleum system of the Transitional complex. Thus the transition complex can be considered as a promising object for hydrocarbons prospecting. Nevertheless, in order to test hypothetical petroleum system additional investigations are required. Further investigations could decrease the main risks associated to the investigated petroleum system - presence of quality hydrocarbon reservoirs. References Lavrenova E., Kruglyakova M. (2010): Specific features of temporal and spatial distributions of light hydrocarbons in the Sea of Azov. Geo-Marine Letters.V 30(3), p. 249-260 (DOI 10,1007/S00367-009-0175-1). Lavrenova, E., Kruglyakova, M., Gorbunov, A., Spahic D., Sokolov, K. (2011): Oil and gas potentials of Azov Sea bar deposits as indicator of active transitional system of hydrocarbon generation and accumulation in eastern part of Sea of Azov (according to results of numerical basin model). 13 EAGE conference. Gelendzik. Russia (in Russian) Stovba S.R., Stephenson S.A. (2003): Style and timing of salt tectonics in the Dniepr-Donets Basin (Ukraine): implications for triggering and driving mechanisms of salt movement in sedimentary basins. Marine and Petroleum Geology 19. p 1169–1189 Petroleum Play Assessment Workshop 13-15 February 2012, Malaga, Spain View publication stats
