Thermodynamic and hydrogeological conditions of forming the hydrocarbon deposits of the Pre-Black Sea aquiferous basin

: pp. 18 - 27
Received: April 02, 2015
Institute of Geology and Geochemistry of Combustible Minerals of NAS of Ukraine
Institute of geology and geochemistry of combustible minerals of NAS of Ukraine
Institute of Geology and Geochemistry of Combustible Minerals of NAS of Ukraine

Purpose. Finding the connection between the thermodynamic conditions of hydrocarbon mixtures synthesis and zones of oil and gas accumulation. Methodology. The thermodynamic eguilibrium depths of gas and gas-condensate deposits were fixed by the method of eguilibrium constants of independent reactions based on the chemical composition of hydrocarbons re-counted on chemical elements. The investigations of formation waters, natural gases and water-dissolved gases were based on the methods of chemical, elementary spectral, atomic absorption and gas chromatographic analysis. Results. Received data point to essential differences in depths of a thermodynamic equilibrium for the deposits of Eocene, Maikopian, and Neogene on the one hand, and Lower Paleocene and Cretaceous sediments on the other. The first ones are characterized by values of depths in boundaries from 30 to 50 km while the second ones show a similar parameters in the boundaries from 120 to150 km. The analysis of the geological, hydrogeological and geochemical circumstances of the Pre-Black Sea aquiferous basin (PBSAB) testified to that the gas-vapour mixtures that are the sources of the Upper Cretaceous, Paleocene and Maikopian gas deposits are formed in high-temperature zone (about 300 C) of depth origin. We consider the Lower Paleocene fields as primary formed only if gases rapidly migrated vertically (in free phase) from high-temperature places of their generation. The ways of possible migration were sublatitudinal faults and zones of decompression. The hydrocarbon fields in Maikopian and even Miocene sediments show the further way of vertical migration of gas and its accumulation in the traps throughout the whole way. Based on the analysis of the hydrogeological, hydro-and gas-geochemical investigations and thermodynamic calculations the model of gas fields forming in PBSAB was carried out. Originality. Hydrogeological data and thermodynamic calculations indicate the depth of origin of hydrocarbons. We suppose that differences in equilibrium depths between the fields of various deposits are coherent with peculiarities of processes of their filling with fluids. The maximum localization of gas-condensate fields at depths of 1900-3000 m testifies not to hydrocarbons formation in this range of depths, but to optimum geology-hydrogeological conditions of forming and of preservation deposits. The migration and preservation of hydrocarbons demand essentially various geology-physical and hydrogeological circumstances: the first is favoured by dynamics of the hydrostatic pressure systems, active tectogenesis, high temperatures, low mineralization of waters; guasistagnat environment, moderate temperatures, presence of the reservoirs that overlapped by reliable seals are favourable for the other. The zone of oil and gas accumulation is related to elisional systems; and zone of through migration to thermohydrodynamic water drive systems. Practical significance. The received data allow forecasting composition of a hydrocarbonaceous component of a field proceeding from its proximity to a decompressions zone and depth of occurrence. We guess that with depth the amount of heavy alkanes will be incremented. The gas condensate fields, on depths more than 1900 m, have a plutonic genesisis. 

  1. 1. Atlas of oil and gas fields of Ukraine, vol. VI, Southern oil-and-gas-bearing region. Lviv, Tsentr Yevropy, 1998, 222 p.
    2. Cortsenshtein V. N. Rastvorjonnye gazy podzemnoj gidrosfery Zemli [Water-dissolved gases of the under¬ground hydrosphere of the Earth]. M., Nedra, 1984, 220 p.
    3. Cortsenshtein V. N. Vodonapornye sistemy krupnejshyh gazovyh i gazokondensatnyh mestoroz-denij SSSR [Water drive systems of the greatest gas and gas-condensate fields of the USSR]. M., Nedra, 1977, 248 p.
    4. Chekaliuk E. B. Termodinamicheskie osnovy teorii mineral'nogo proishozdenija nefti [Thermodynamic basement of the mineral genesis theory of forming oil]. Kyiv, Naukova dumka, 1971, 265 p.
    5. Huizenga J. M. Thermodynamic modeling of C-O-H fluids // Lithos, 2001, vol. 55. pp. 101–114.
    6. Karpov I. K. Fizikohimicheskoe modelirovanie na EVM v geohimiji [Computed physicochemical modelling in geochemical]. Novosibirsk, Nauka, 1981, 247 p.
    7. Khokha Yu. V. Termodynamica glybynnych vuglevodniv u prognozuvanni regional'noji naftoga-zonosnosti [Thermodynamics of abyssal hydrocarbons in forecast of regional oil and gas bearingness]. Kyiv, Naukova dumka, 2014, 56 p.
    8. Khokha Yu., Lyubchak O. Aktyvnist' vody v termodynamichnyh umovynah Zemnoji kory ta verhnjoji mantii [Water activity in thermodynamic conditions of the Earth crust upper mantle]. Geologija i Geokhimija goryuchyh kopalyn, 2005, no. 3–4, pp. 104–109.
    9. Kolodiy V. V., Kolodiy I. V. Model' formuvannja gazovyh pokladiv v akvatoriji Pivnichnoprychor-nomors'kogo vodonapirnogo basejnu [The model of forming gas fields of the Northern Black Sea aquiferous basin]. Geologija i Geokhimija goryuchyh kopalyn, 2002, no. 4, p. 11–20.
    10. Kolodiy I. V. Rol' procesiv migraciji u for¬muvanni gazogeohimichnoji zonal'nosti v akvatoriji Pivnichnoprychornomors'kogo vodonapir¬nogo ba-sejnu [The role of migration to forming gas-geochemical zoning of the Northern Black Sea aquiferous basin]. Suchasni problemy geologichnoji nauky . Sb. nauk. pr. –K., 2003, pp. 29–30.
    11. Kolodiy V. V., Kolodiy I. V. Gidrogeologicheskie dokazatel'stva uslovij genezisa, migracii i formirovanija zalezej uglevodorodov [Hydrogeolo-gical evidences of genesis, migration and forming hydrocarbon fields]. Neftegazovaja gidrogeologija na sovremennom etape. Sb. nauch. tr. –Moskva, GEOS, 2007, pp. 36–46.
    12. Kolodiy I. V. Prognozuvannja lokalizaciji vuglevodnevyh skupchen' Prychornomors'kogo vodo¬napirnogo ,basejnu za gidrogeohimichnymy pokaz¬nykamy [Expected localization of hydrocarbon depozits of the Black Sea aquiferous basin based on hydrogeochemical indications]. Visnyk HNU imeni V. N. Karazina. – K.,2014, no 1128, pp. 32–36.
    13. Lyubchak O., Khokha Yu. Termodinamicheskie uslovija formirovanija alkanov (C1–C20) v Zemnoj kore i Verhnej Mantii [Thermodynamic conditions of forming alkanes (C1-C20) of the Earth crust and Upper Mantle] Tezisy konferentsii "Degazacija Zemli. Geodinamica, geofliuidy, neft', gaz i ih paragenezisy" [Proc. of the conf. "Degassing of the Earth. Geo¬dynamic, geofluids, oil, gas and their paragenesises"]. Moskva, GEOS, 2008, pp. 300–303.
    14. Ryuichi Sugisaki, Koichi Mimura. Mantle hydrocarbons: Abiotic or biotic? // Geochimica et Cosmochimica Acta, 1994, vol. 58, pp. 2527–2542.
    15. Sollogub V. B., Sologub N. V. Tectonika Odes'ko-Dzankojs'koji ryftovoji zony [Tectonics of Odesa-Dzhankoy rift zone] Dop. AN USSR. Ser B. Geoo-gichni, himichni ta bioogichni nauky, 1982, no.10. pp. 22–24.
    16. Zubkov V. S., Stepanov A. N., Karpov I. K., Bychinskii V. A. Termodinamicheskaja model' sistemy C-H v uslovijah vysokih temperatur i davlenij [Thermo¬dynamic model of C-H system in high temperature and pressure conditions]. Geochi-mija,1998, no. 1, pp. 95–101.
    17. C. Zhang, Z. Duan (2009), A model for C-O-H fluid in the Earth's mantle // Geochimica et Cosmochimica Acta, 2009, vol. 73, pp. 2089–2102.