The role of young fracturing in the formation and spatial distribution of hydrocarbon deposits in the North-Western Caspian Sea

UDK: 553.98.061.32
DOI: 10.24887/0028-2448-2018-5-36-39
Key words: rocks, newest geodynamics, fracture network, migration, deposit
Authors: N.A. Kasyanova (Gubkin Russian State University of Oil and Gas (National Research University), RF, Moscow)

The article presents the results of studying the role of rocks fracturing in the formation and spatial distribution of hydrocarbon deposits in the North-Western Caspian Sea. A comprehensive study of the features of the rocks internal structure, their spatial oil saturation and the relationships between them has been carried out. As a source data, a large amount of core material and the latest information on the geological structure, oil and gas content and geodynamic development of the territory at the final stage of geological history were used.

The leading role of differently oriented zones of increased early age fracturing (two young generations) in the formation and spatial distribution of hydrocarbon deposits in this water area has been established. It is noted that a special role is played by a horizontally oriented complex (multi-stage) zone of increased fracturing, regionally developed in the earth's crust in the interval of thicknesses of rocks of the Middle Jurassic-Early Cretaceous age. It is established that this large zone of low-amplitude disjunctive dislocations controls the range of regional oil and gas content  of the Middle Jurassic-Lower Cretaceous sediments, as well as the selective (through the section) oil saturation of rocks within productive layers. It is determined that the non-uniform (up to thin-layered) character of the oil saturation of contemporaneous rocks within the limits of one productive horizon (layer) does not have a direct connection with the lithologic-petrophysical characteristics of rocks, and is always associated with the presence of a horizontal oil-saturated fracture network in them.

The early age and the ongoing two-stage formation of hydrocarbon deposits within the water area of the North-Western Caspian are justified. Conclusions and results are valid for all deposits in the North-Western Caspian Sea. The obtained results can also be used for carrying out of prospecting and exploration in other regions (onshore and offshore), where zones of high fracturing are the primary exploration targets.

References

1. Agzyamov K.G., Bagov L.S., Makhonin M.V., Paleotektonicheskiy analiz podnyatiy Khvalynskoe i “170 km” (Paleotectonic analysis of Khvalynske and 170 km upheavals), Collected papers “Geologiya, burenie i razrabotka neftyanykh mestorozhdeniy Prikaspiya i Kaspiyskogo morya” (Geology, drilling and development of oil deposits of the Caspian Sea and the Caspian Sea), 2003, V. 61, pp. 132–136.

2. Bayukanskiy Yu.F., Noveyshaya tektonika i neftegazonosnost’ rossiyskogo sektora Severnogo i Srednego Kaspiya (The newest tectonics and oil and gas potential of the Russian sector of the Northern and Middle Caspian): thesis of candidate of geological and mineralogical science, Moscow, 2007.

3. Kas’yanova N.A., Vliyanie sovremennoy geodinamiki na neftegazonosnost’ Kavkazsko-Skifskogo regiona (Influence of modern geodynamics on the oil and gas content of the Caucasus-Scythian region), Moscow: Geoinformmark Publ., 1995, 55 p.

4. Kas’yanova N.A., New concept for the structure and formation of the North Caspian Rakushechno-Shirotnyi swell (In Russ.), Geologiya nefti i gaza = The journal Oil and Gas Geology, 2017, no. 1, pp. 24–31.

5. Ostroukhov S.B., Bochkarev V.A., Vorontsov R.A. et al., Nekotorye aspekty formirovaniya zalezhey uglevodorodov mestorozhdeniya im. V.P. Filanovskogo (Some aspects of the formation of hydrocarbon deposits of the V.P. Filanovsky), Collected papers “Voprosy osvoeniya neftegazonosnykh basseynov” (The issues of development of oil and gas basins), 2008, V. 67, 74 p.вЃ  

The article presents the results of studying the role of rocks fracturing in the formation and spatial distribution of hydrocarbon deposits in the North-Western Caspian Sea. A comprehensive study of the features of the rocks internal structure, their spatial oil saturation and the relationships between them has been carried out. As a source data, a large amount of core material and the latest information on the geological structure, oil and gas content and geodynamic development of the territory at the final stage of geological history were used.

The leading role of differently oriented zones of increased early age fracturing (two young generations) in the formation and spatial distribution of hydrocarbon deposits in this water area has been established. It is noted that a special role is played by a horizontally oriented complex (multi-stage) zone of increased fracturing, regionally developed in the earth's crust in the interval of thicknesses of rocks of the Middle Jurassic-Early Cretaceous age. It is established that this large zone of low-amplitude disjunctive dislocations controls the range of regional oil and gas content  of the Middle Jurassic-Lower Cretaceous sediments, as well as the selective (through the section) oil saturation of rocks within productive layers. It is determined that the non-uniform (up to thin-layered) character of the oil saturation of contemporaneous rocks within the limits of one productive horizon (layer) does not have a direct connection with the lithologic-petrophysical characteristics of rocks, and is always associated with the presence of a horizontal oil-saturated fracture network in them.

The early age and the ongoing two-stage formation of hydrocarbon deposits within the water area of the North-Western Caspian are justified. Conclusions and results are valid for all deposits in the North-Western Caspian Sea. The obtained results can also be used for carrying out of prospecting and exploration in other regions (onshore and offshore), where zones of high fracturing are the primary exploration targets.

References

1. Agzyamov K.G., Bagov L.S., Makhonin M.V., Paleotektonicheskiy analiz podnyatiy Khvalynskoe i “170 km” (Paleotectonic analysis of Khvalynske and 170 km upheavals), Collected papers “Geologiya, burenie i razrabotka neftyanykh mestorozhdeniy Prikaspiya i Kaspiyskogo morya” (Geology, drilling and development of oil deposits of the Caspian Sea and the Caspian Sea), 2003, V. 61, pp. 132–136.

2. Bayukanskiy Yu.F., Noveyshaya tektonika i neftegazonosnost’ rossiyskogo sektora Severnogo i Srednego Kaspiya (The newest tectonics and oil and gas potential of the Russian sector of the Northern and Middle Caspian): thesis of candidate of geological and mineralogical science, Moscow, 2007.

3. Kas’yanova N.A., Vliyanie sovremennoy geodinamiki na neftegazonosnost’ Kavkazsko-Skifskogo regiona (Influence of modern geodynamics on the oil and gas content of the Caucasus-Scythian region), Moscow: Geoinformmark Publ., 1995, 55 p.

4. Kas’yanova N.A., New concept for the structure and formation of the North Caspian Rakushechno-Shirotnyi swell (In Russ.), Geologiya nefti i gaza = The journal Oil and Gas Geology, 2017, no. 1, pp. 24–31.

5. Ostroukhov S.B., Bochkarev V.A., Vorontsov R.A. et al., Nekotorye aspekty formirovaniya zalezhey uglevodorodov mestorozhdeniya im. V.P. Filanovskogo (Some aspects of the formation of hydrocarbon deposits of the V.P. Filanovsky), Collected papers “Voprosy osvoeniya neftegazonosnykh basseynov” (The issues of development of oil and gas basins), 2008, V. 67, 74 p.вЃ  



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