Classic and anomalous objects identified as a result of geological exploration at the area of Irkutsk Oil Company

UDK: 553.98
DOI: 10.24887/0028-2448-2020-9-26-29
Key words: Eastern Siberia, barrier reef, ancient paleovolcano, Mirninsky ledge, downleap-upleap structure, Parfenov bar, flow system, Yaraktinskian horizon, Osinskian horizon, Irkutsk region
Authors: M.Yu. Nikulina (Irkutsk Oil Company LLC, RF, Irkutsk), N.V. Myshevsky (Irkutsk Oil Company LLC, RF, Irkutsk), E V. Nikulin (Irkutsk Oil Company LLC, RF, Irkutsk)

The article highlights the volume of work performed related to the search and exploration of deposits. The article considers anomalous (atypical) objects identified by the company's geologists in the areas of the Irkutsk region and the Republic of Sakha (Yakutia), identified during geological exploration. Large barrier-type carbonate structures surrounding the paleodepression of the Irkutsk amphitheater have been mapped. The reservoir is represented by pore-cavern type dolomites formed from limestone by secondary processes. The necessary and sufficient criteria for searching for hydrocarbon deposits in the Osinskian horizon have been developed. Structural and tectonic objects were found in the Mirninsky region (Yakutia) using 3D seismic survey. The conceptual scheme of distribution of bar bodies of the Botuobinskian and Ulakhanskian horizons is presented. Significant amounts of oil resources were identified. Based on the generalization of seismic survey materials and deep drilling data, a large sandy strip in the Parfenovskian horizon with significant hydrocarbon potential has been localized, extending over the Bolshetirsky, Verkhnetirsky, Yalyksky and Verkhnekatangsky license areas. The properties of reservoirs based on well data are given. Fluvial system of the Ayanskoye field is considered, paleoflows and microhills of the basement in the form of a pulse of seismic reflecting horizons are dedicated. The drainage system is mapped in detail. The dependence of net to gross shale and distance from the geomorphological bodies is revealed. A large isometric anomaly has been identified at the Yaraktinskoye field, presumably an ancient paleovolcano with a total area of more than 60 km2. The genesis issues are considered and the forecast of the distribution of a terrigenous reservoir associated with the features of sedimentation of an ancient structure is given. The prospects of the object associated with the appearance of new reservoirs in the section of wells are given. As a result of exploratory drilling and 3D seismic surveys to the south of the Dulisminskoye and Yaraktinskoye fields at a distance of 45 km from the latter, a sandbar in the Yaraktinskian horizon was found and mapped down the dip of monocline structure, from which the rates of hydrocarbon inflows production were obtained. Properties of reservoirs are given.

References

1. Kolotovkina M.Yu., Facial zoning of the Vendian productive deposits of the Yaraktinskoe oil and gas-condensate field (In Russ.), Geologiya, geofizika i razrabotka neftyanykh i gazovykh mestorozhdeniy, 2018, no. 3, pp. 14–25.

2. Myshevskiy N.V., Ignalina Barrier Reef – a new promising object on the Nepa Arch (In Russ.), Geologiya i geofizika, 1991, no. 11, pp. 99–107.

3. Shemin G.G., Geologiya i perspektivy neftegazonosnosti venda i nizhnego kembriya tsentral'nykh rayonov Sibirskoy platformy (Nepsko-Botuobinskaya, Baykitskaya anteklizy i Katangskaya sedlovina) (Geology and oil and gas potential Vendian and Lower Cambrian deposits of central regions of the Siberian Platform (Nepa-Botuoba, Baikit anteclise and Katanga saddle)): edited by Kashirtsev V.A., Novosibirsk: Publ. of SB RAS, 2007, 467 p.

The article highlights the volume of work performed related to the search and exploration of deposits. The article considers anomalous (atypical) objects identified by the company's geologists in the areas of the Irkutsk region and the Republic of Sakha (Yakutia), identified during geological exploration. Large barrier-type carbonate structures surrounding the paleodepression of the Irkutsk amphitheater have been mapped. The reservoir is represented by pore-cavern type dolomites formed from limestone by secondary processes. The necessary and sufficient criteria for searching for hydrocarbon deposits in the Osinskian horizon have been developed. Structural and tectonic objects were found in the Mirninsky region (Yakutia) using 3D seismic survey. The conceptual scheme of distribution of bar bodies of the Botuobinskian and Ulakhanskian horizons is presented. Significant amounts of oil resources were identified. Based on the generalization of seismic survey materials and deep drilling data, a large sandy strip in the Parfenovskian horizon with significant hydrocarbon potential has been localized, extending over the Bolshetirsky, Verkhnetirsky, Yalyksky and Verkhnekatangsky license areas. The properties of reservoirs based on well data are given. Fluvial system of the Ayanskoye field is considered, paleoflows and microhills of the basement in the form of a pulse of seismic reflecting horizons are dedicated. The drainage system is mapped in detail. The dependence of net to gross shale and distance from the geomorphological bodies is revealed. A large isometric anomaly has been identified at the Yaraktinskoye field, presumably an ancient paleovolcano with a total area of more than 60 km2. The genesis issues are considered and the forecast of the distribution of a terrigenous reservoir associated with the features of sedimentation of an ancient structure is given. The prospects of the object associated with the appearance of new reservoirs in the section of wells are given. As a result of exploratory drilling and 3D seismic surveys to the south of the Dulisminskoye and Yaraktinskoye fields at a distance of 45 km from the latter, a sandbar in the Yaraktinskian horizon was found and mapped down the dip of monocline structure, from which the rates of hydrocarbon inflows production were obtained. Properties of reservoirs are given.

References

1. Kolotovkina M.Yu., Facial zoning of the Vendian productive deposits of the Yaraktinskoe oil and gas-condensate field (In Russ.), Geologiya, geofizika i razrabotka neftyanykh i gazovykh mestorozhdeniy, 2018, no. 3, pp. 14–25.

2. Myshevskiy N.V., Ignalina Barrier Reef – a new promising object on the Nepa Arch (In Russ.), Geologiya i geofizika, 1991, no. 11, pp. 99–107.

3. Shemin G.G., Geologiya i perspektivy neftegazonosnosti venda i nizhnego kembriya tsentral'nykh rayonov Sibirskoy platformy (Nepsko-Botuobinskaya, Baykitskaya anteklizy i Katangskaya sedlovina) (Geology and oil and gas potential Vendian and Lower Cambrian deposits of central regions of the Siberian Platform (Nepa-Botuoba, Baikit anteclise and Katanga saddle)): edited by Kashirtsev V.A., Novosibirsk: Publ. of SB RAS, 2007, 467 p.



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