DOI: https://doi.org/10.24028/gzh.0203-3100.v41i2.2019.164456

A thermobaric mechanism for the formation of low velocity zones in the crystalline crust of the northwestern Black Sea shelf: a new type of traps for abiogenic methane

V. A. Korchin, O. M. Rusakov

Abstract


Seismic studies of the NW Black Sea shelf have delineated low-velocity zones (LVZs) in the crystalline crust at depths of 6—16 km. For the first time, this paper presents a novel thermodynamic mechanism for their formation. The active temperature regime and deep geodynamic processes of the region provide evidence in favour of this mechanism. The LVZs are mainly associated with the thermal decompaction of rocks, which is not compensated by deep pressures. The rocks of such zones are characterized by an increase in fracturing and porosity and decrease in density, elastic parameters and thermal conductivity. As the rocks are permeable and hygroscopic they are able to more freely transform, absorb and localize mantle hydrocarbon-bearing fluids which, in turn, further destroy rock matter. Within the LVZs the existence of hydrocarbons is confirmed by the occurrence about 3200 activegas seeps and 8 gas and gas condensate fields. For the first time, the spatial coexistence was revealed between LVZs and a degassing tube to which hydrocarbon fields are related.

LVZs zones should be considered as a new search criteria for thermobaric traps. Favou­rable conditions exist for the accumulation of abiogenic methane at a depth of 6—16 km that can substantially expand the hydrocarbon potential of the shelf in usage modern drilling technology.


Keywords


NW Black Sea shelf; upper crystalline crust; low velocity zones; petrophysical thermobaric model; regional abiogenic methane trap

References


Bazhenova, O. K., Fadeeva, N. P, Saint-Ger¬mes, M. L.,&Tikhomirova, E. E. (2003). Sedi-men¬tation conditions in the Eastern Paratethis Oce¬an in the Oligocene—Early Miocene. Vestnik Moskovskogo universiteta, Ser. Geologiya, (6), 12—19 (in Russian).

Baranova, E. P., Yegorova, T. P., & Omelchenko, V. D. (2011). Detection of a waveguide in the basement of the northwestern shelf of the Black Sea according to the results of reinterpretation of the DSS materials of profiles 26 and 25. Geofizicheskiy zhurnal, 33(6), 15―29. https://doi.org/10.24028/gzh.0203-3100.v33i6.2011.116790 (in Russian).

Karakin, A. V., Kuryanov, Yu. A., & Pavlenkova, N. I. (2003). Fractures, fractured zones and waveguides in the upper layers of the earth envelope. Moscow: State Scientific Center of the Russian Federation, VNIIgeosystem, 222 p. (in Russian).

Kozlenko, M. V., & Kozlenko, Yu. V. (2014). The structure and evolution of lithosphere of the central part of the northwestern shelf of the Black Sea. Geofizicheskiy zhurnal, 36(4), 65―74. https://doi.org/10.24028/gzh.0203-3100.v36i4.2014.116025 (in Russian).

Korchin, V. A. (2013). Thermodynamics of crustal zones of low seismic velocities (new scientific hypothesis). Saarbrьcken: LAP Lambert Academic Publishing, 280 p. (in Russian).

Korchin, V. А. (2014). Thermobaric modeling of anomalies of increased porosity in the rocks of the Earth’s crust ― horizons of possible migration and localization of deep hydrocarbons. Electronic magazine «Glubinnaya neft», 2(9), 1434―1448 (in Russian).

Korchin, V. A., Burtny, P. A., & Karnaukhova, E. E. (2018). Decompaction of metamorphic rocks under thermodynamic conditions of the Earth’s crust (experimental data). Geofizicheskiy zhurnal, 40(4), 107―130. https://doi.org/10.24028/gzh.0203-3100.v40i4.2018.140612 (in Russian).

Korchin, V. А., Burtny, P. А., & Kobolev, V. P. (2013). Thermobaric petrophysical modeling in geophysics. Kiev: Naukova Dumka, 312 p. (in Russian).

Kutas, R. I. (2011). Geothermal sections of the Earth’s crust and upper mantle of the Black Sea and its northern border. Geofizicheskiy zhur¬nal, 33(6), 50―67. https://doi.org/10.24028/gzh. 0203-3100.v33i6.2011.116792 (in Russian).

Kutas, R. I. (1978). Thermal flux field and a theoretical model of the Earth’s crust. Kiev: Naukova Dumka, 140 p. (in Russian).

Lukin, A. Ye., & Shestopalov, V. M. (2018). From new geological paradigm to the problems of regional geological and geophysical survey. Geofizicheskiy zhurnal, 40(4), 3―72. https://doi.org/10.24028/gzh.0203-3100.v40i4.2018.140610 (in Russian).

Pavlenkova, N. I. (1973). Wave fields and models of the Earth’s crust (continental type). Kiev: Naukova Dumka, 129 p. (in Russian).

Rusakov, O. M., & Korchin, V. А. (2015). The origin and localization of abiogenic methane in the crystalline crust of the northwestern part of the Black Sea. Materials of the All-Russian Conference on the Deep Genesis of Oil «4th Kudryavtsev Readings». Moscow: JSC «Central Geophysical Expedition», CD (in Russian).

Rusakov, O. M., & Kutas, R. I. (2014). Fata morgana of biogenic doctrine of hydrocarbons in the Black Sea. Geofizicheskiy zhurnal, 36(2), 3―17. https://doi.org/10.24028/gzh.0203-3100.v36i2.2014.116113 (in Russian).

Startostenko, V. I., Makarenko, I. B., Rusakov, O. M., Pashkevich, I. K., Kutas, R. I., & Legostaeva, O. V. (2010). Geophysical geterogeneity of the lithosphere of the megabasin of the Black Sea. Geofizicheskiy zhurnal, 32(5), 3―20. https://doi.org/10.24028/gzh.0203-3100.v32i5.2010.117496 (in Russian).

Starostenko, V. I., Lukin, A. E., Rusakov, O. M., Pashkevich, I. K., & Lebed, T. V. (2015). Hydrocarbon through a fluid-carrying channel on the north-western Black Sea shelf from three dimensional magnetic modelling. Geologiya i poleznyye iskopayemyye Mirovogo okeana, (2), 147―158 (in Russian).

Timurziev, A. I. (2007). To the creation of a new paradigm of oil and gas geology based on a deep-filtration model of oil and gas formation and oil and gas accumulation. Geofizika, (4), 49―60 (in Russian).

Chebanenko, I. I., Krayushkin, V. A., & Klochko, V. P. (2002). Oil and Gas Perspective Objects of Ukraine. Oil and gas basement. Kiev: Naukova Dumka, 296 p. (in Russian).

Etiope, G., & Sherwood Lollar, B. (2013). Abiotic methane on Earth. Reviews of Geophysics, 51, 276—299. doi: 10.1002/rog.20011.

Ivanov, M. K, & Lein, A. Yu. (2006). Fractionation of stable isotopes of carbon and sulfur during biological processes in the Black Sea. In: L. N. Neretin (Ed.), Past and present water column anoxia (pp. 373—417). Dordrecht: Springer. https://doi.org/10.1007/1-4020-4297-3_15.

Korchin, V. Anomalies of low density in the crystalline crust of thermobaric origin: a new insight into migration and localization of hydrocarbons. Monograph 72: Oil and Gas Exploration: Methods and Application. American Geophysical Union, Wiley, 2017, рр. 237—257.

Kucherov, V. G., & Krayushkin, V. A. (2010). Deep-seated abiogenic origin of petroleum: From geological assessment to physical theory. Reviews of Geophysics, 48(1), RG1001. doi:10.1029/2008RG000270.

Reeburgh, W. S., Ward, B. B., Whalen, S. C., Sandbeck, K. A., Kilpatrick, K. A., & Kerkhof, L. J. (1991). Black-sea methane geochemistry. Deep-Sea Research Part A. Oceanographic Research Papers, 38, S1189—S1210. https://doi.org/10.1016/S0198-0149(10)80030-5.

Rusakov, O. M., & Kutas, R. I. (2018). Mantle origin of methane in the Black Sea. Geofizicheskiy zhurnal, 40(5), 191—207. https://doi.org/10.24028/gzh.0203-3100.v40i5.2018.147482.

Simmons, M. D., Tari, G. C., & Okay, A. I. (Eds.). (2018). Petroleum Geology of the Black Sea. Introduction. Geological Society, London, Special Publication, 464, 1―18. https://doi.org/10.1144/SP464.15.

Starostenko, V. Janik, T., Yegorova, T., Farfuliak, L., Czuba, W., Środa, P., Thybo, H., Artemieva, I., Sosson, M., Volfman, Y., Kolomiyets, K., Lysynchuk, D., Omelchenko, V., Gryn, D., Guterch, A., Komminaho, K., Legostaeva, O., Tiira, T., & Tolkunov, A. (2015). Seismic model of the crust and upper mantle in the Scythian Platform: the DOBRE-5 profile across the western Black Sea and the Crimea Peninsula. Geophysical Journal International, 201(1), 406—428. https://doi.org/10.1093/gji/ggv018.




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