20 Issue 3: 2016 collection Impact of fault tectonics to the oil-and-gas-bearing capacity of Vendian & Lower-Cambrian deposits at the southern regions of the Siberian platform (Nepa-Botuoba anteclise and contiguous territories) O.V. Ivchenko*, Ye.Ye. Polyakov, M.V. Ivchenko Gazprom VNIIGAZ LLC, Bld. 1, Estate 15, Proyektiruemyy proezd # 5537, Razvilka, Leninsky District, Moscow Region, 142717, Russian Federation * [email protected] Keywords: Abstract. Nowadays the region of Nepa-Botuoba anteclise is the main oil-gas-bearing area in the Sakha Nepa-Botuoba (Yakutiya) Republic and the Irkutsk region. Here a large amount of geological surveys is being carried out anteclise, including 3D-seismics. As a result of reinterpreting profiles got in previous years and interpreting new data prospects for oil- the notion about structure and tectonics of oil and gas fields changes. Revelation of fault tectonics influence and-gas-bearing on the oil-gas-bearing capacity of structures will enable to improve design procedure for development capacity, of fields and to determine optimum locations of extractive wells being developed. Vendian & Lower- Tectonic factor makes a considerable impact on generation and accumulation of hydrocarbons. Cambrian reservoir, Essential part of hydrocarbon fields is dated to fault anticlinal structures of various orders. In respect fault tectonics, to explored territory tectonic factor is of special importance due to complicatedness of sedimentary fault, cover structure: in particular due to linear folding, lots of faults and trap intrusions, development of karst imbricated processes. Tectonic development of the region directly influenced the character of hydrocarbon deposits’ overthrust, localization. In order to determine their affiliation with structures one should study ancient structural plan, intrusive trap, but not a modern one. trap magamatism In this article most attention is payed to disjunctive breaks, which execute two main tasks in the examined region: they demarcate different blocks of one deposit and screen hydrocarbon flows at an external loop of the deposit. Saturation of sediments with magmatic rocks in the central regions of the Siberian Platform is insignificant. They amount to nearly 3 % of platform cover volume (this is much less than in the north- west regions of Siberian Platform) and are presented mostly by stratum intrusive bodies (sills). Transversal bodies (dikes) demonstrate limited areal distribution. Trap magmatic formations bed stratigraphically higher than the main productive horizons of the anteclise (only districts of Usolye and Upper Danilov reservoirs are situated within the zone of their influence) at more than 30 stratigraphuc levels in Vendian and Lower- Cambrian carbonate and haloid-carbonate sediments of Lower-, Middle- and Upper-Danilov, Usolye, Elgyay, Lower- and Upper-Tolbachik, Olekminsk and Chara regional cyclites. These traps slightly influence the oil-gas-bearing capacity of sediments. Structures of exogenous nature are developed predominantly in the upper part of the Nepa-Botuoba sedimentary cover. Main are the karst-connected sediments. Today the area of the Nepa-Botuoba anteclise (NBA) is the main oil and gas bearing area in the Republic of Sakha (Yakutia) and the Irkutsk Region. Here a large scope of exploration as well as 3D seismic exploration are being performed. The understanding of the structural and tectonic fi eld structure changes as the result of re-interpretation of profi les of previous years and interpretation of new data. Identifi cation of the features of impact of fault tectonics on the oil and gas content will allow for improvement of the fi eld development design methodology and for determination of optimal places for producing well drilling in the future. NBA is one of the most important oil and gas belts of Eastern Siberia. According to current understanding, it has a slightly asymmetric fusiform shape and is stretched at the distance of more than 1 th. km at the width of up to 400 km. Its area exceeds 250 th. km2. The thickness of the sedimentary mantle varies from 1,5 km in the roof part to 3 km at the periphery [1]. In the administrative relation the southwestern part of the anteclise is a part of the Irkutsk Region and partially the Krasnoyarsk Territory, and its northeastern part – the Republic of Sakha (Yakutia). The structure under study is stretched from the latitude 56° (interfl uve of the Lena and Ilim rivers) in the northeastern direction to the latitude 64° (watershed of the Vilyui and Morkoka rivers) (Figure 1). In terms of the number of discovered English-language digest Proceedings of Gas Industry Research and Development 21 Udachny Syugdzherskaya OGR Aikhal Anabar OGR Predverkhoyanskaya OGR Andylakhskoye Ust-Vilyui Kyubeyingde Sangar Srednetyungskoye Nizhnevilyuiskoye Severo-Tungus OGR Kysyl-Syr Mastakhskoye Khatanga-Vilyui OGPBadaranskoye Tura Srednevilyuiskoye Tolonskoye Sobolokh-Nedzhelinskoye Vilyuisk Mastakh Namtsy Zapadno-Vilyuiskaya OGR Nizhnetyukyanskoye Ebya Byas’-Kyuyol’ Vilyui OGR Kerdyugen Verkhnevilyuisk Nyurba Yakutsk Arylakh Syuldyukar Lena-Tungus OGP Vladimirovka Svetly Berdigestyakh Pokrovsk Nakanno Chernyshevsky Dikimdya Bestyakh Mirny Stanakhskoye Irelyakh Suntar Yelanka Nelbinskoye Kempendyay Mirninskoye Iktekh Vilyuisko-Dzherbinskoye Tas-Yuryakh Severo-Aldanskaya OGR Besyuryakh Verkhnevilyuchanskoye Katanga OGR Tas-Yuryakh Srednebotuobinskoye Yerbogachyon Otradninskoye Khotogo-Murbaiskoye Bechencha Olyokminsk Solyanka Lensk Nyuya Bysakhtakhskoye Neryuktyayinsk 1st Vanavara Vakunaiskoye Chayanda Tympuchikanskoye Tommot Baikit OGR Severo-Talakanskoye Paiginskoye Verkhnechonskoye Ust-Seligdar Sobinskoye Talakan (Eastern block) Khatystyr Nepa-Botuoba OGR Talakan (Taran block) Aldan Yakokut Verkhnepeleduiskoye Peledui Vostochno-Alinskoye Danilov Lebediny Vitim Talakh-Ary Perevoz Katalakh Kezhma Marakan Kankunsky Dulisminskoye Keul’ Mama Pilyudinskoye Pre-Patom OGR YaraktinskoyeNadezhdinsk Bolshoy Severny Ayanskoye Ust-Ilimsk Petropavlovsk Bodaibo Kirensk Alekseyevsk Gorno-Chuisky Mamakan hydrocarbon fields Novoilimsk Chara oil and gas regions Radishchev Nov. Igirma Markovskoye settlements Kezhemsky Angara-Lena OGR Ust-Kut Bratskoye Zheleznogorsk-Ilimsky main regional faults Vikhorevka Shestakovo Korshunovsky Taksimo Kazachinskoye Bratsk Zayarsk Novy Uoyan faults confirmed by drilling Magistralny Kholodny Shumilovo Fig. 1. Review map of the oil and gas content of NBA (with neighbouring areas) with indication of main elements of fault tectonics (as per the data of the Laboratory for geological and economical effi cacy of subsoil use of the Centre for Hydrocarbons Reserves and Resources of Gazprom VNIIGAZ LLC, 2015) fi elds and prepared oil and gas reserves NBA takes in terms of the type of the reservoir – stratal (90 %) the leading position in the Lena-Tungus oil and and in terms of the structure – block (60 %); gas province (OGP). It is a part of the cognominal • the lithological control determines the oil and gas region (OGR) and is the main target borders of deposits in 27 (54 %), tectonic – of oil and gas prospecting throughout the Siberian in 29 (58 %), and stratigraphic – in 8 (16 %) platform. cases; for the deposits controlled by a lithological The tectonic factor has signifi cant impact factor the most widely distributed (60 %) are the on generation and accumulation of hydrocarbons. following limitations: tectonic screening (48 %) The signifi cant part of hydrocarbon (HC) fi elds and stratigraphic thinning out (12 %). Thereat, is confi ned to fault anticline structures of different it is worth noting that the researchers took into orders. The tectonic factor gains a specifi c account only the main largest HC deposits value within the surveyed area due to extremely since minor lithologically closed ones are complicated structure of the sedimentary mantle – of no industrial value. presence of linear folding, abundance of faults, In the tectonic relation NBA is located saturation with trappean intrusions, development in the southern half of the Siberian platform and of karst processes. borders major negative structures – the Sayan- Paper [2] provides the following statistic Yenisey, Kureiskaya syneclises and the pre-Patom conclusions on typifi cation of HC deposits regional downfold in the southwest, northwest in relation to structural and lithological control: and southeast (Figure 2). In the south it contours • most of HC deposits in terms of the form the Angara-Lena stage and in the west and of structural trap control are non-anticlinal (58 %), north across the Katanga and Syugdzherskaya Vesti Gazovoy Nauki scientific and technical collected book 22 Ÿ Kureiskaya Turinskaya depression Vilyui Vilyui Andylakhskoye Ÿ Ust-Vilyui Lindenskaya depression Ÿ Srednetyungskoye Nizhnevilyuiskoye Khapchagaisky megabar syneclise Tolonskoye Badaranskoye Srednevilyuiskoye Lungkhinsko- Kelinsky megadownfold Mastakhskoye Sobolokh-Nedzhelinskoye Ÿ Syugdzherskaya saddle hemisyneclise Nakannovsky projection Yakutsko-Amginsky projection Irelyakh Suntarsky arc Ygyattinskaya depression Machchobinskoye Stanakhskoye Kempendyaiskaya depression Mirninskoye Ÿ Tas-Yuryakh Vilyuisko-Dzherbinskoye Ÿ Iktekh Verkhnevilyuchanskoye Srednebotuobinskoye Besyuryakh Otradninskoye Aldan anteclise Tolbinsky megaprojection Khotogo-Murbaiskoye Ÿ Chayanda Bysakhtakhskoye Vakunaiskoye depression Dzheyuktinsky projection Paiginskoye Nyuisko-Dzherbinskaya Tympuchikanskoye Severo-Talakanskoye Sobinskoye Verkhnechonskoye Sobinsko-Tetersky Verkhnepeleduiskoye