«OIL AND GAS GEOLOGY» № 6/2017

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Geologiya Nefti I Gaza" ("Oil And Gas Geology") is included by the Higher Attestation Commission in the list of leading scientific journals and publications where the main scientific results of dissertations for the degree of candidate and doctor of sciences

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CONTENTS

 

OIL AND GAS POTENTIAL AND GEOLOGICAL EXPLORATION RESULTS

 

V.S. Shein, A.V. Alferenok, S.L. Kalamkarov, А.А. Knipper, V.A. Shein. Tectonic structure and oil and gas potential of Western Arctic basement and adjacent regions

 

The authors show forth their views on formation of different types of basement from the standpoint of the lithosphere plate tectonics. Under the sedimentary cover of the Western Arctic and adjacent regions they identify basement types as follows: continental, sub-continental, oceanic, sub-oceanic and folded basement, and also the oceanic basement occurring in the allochthonous attitude. The contours of their occurrence are determined and the depths of surfaces of the various types of basement are shown. Possibility of discovery of small and medium-size fields are discussed in the following succession: prospective deposits of the folded basement, primarily Paleozoic deposits; promising rocks of the continental and sub-continental basements, as well as oceanic basement in allochthonous tectonic plate-lets; and unpromising sections of the oceanic and sub-oceanic basements, as well as outcropping rocks of the continental and folded basements. Succession of studies of the structure and oil and gas potential of the region basement is proposed.

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O.A. Vazhenina, A.V. Trigub, I.V. Privalova. Hydrocarbon deposits search prospects in vogulkinskaya stratum sediments (layer П) based on seismic and geological data combination

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Nowadays, there is a great need in searching for new stratigraphic levels that are perspective for oil and gas. The authors of the article describe the methodology and results of seismogeological studies carried out to identify zones and areas favorable for the hydrocarbon deposits search in the Vogulkinskaya sedimentary rocks. For this purpose, two regions were considered: the south-western part of the Yamal-Nenets Autonomous District and the north-western part of the Tyumen South Region. Features of paleogeographic and tectonic history of these areas development have led to a gradual wedging of Lower, Middle and Upper Jurassic deposits. According to the authors, the attention of researchers in order to detect hydrocarbon deposits in the Vogulkinskaya sedimentary rocks should be paid particularly in such regions. In the article the main types of productive sections in sediments of layer П are considered and characterized, kondinskiy, shaimskiy and berezovskiy sections were taken as standards. The paper largely focuses on the methods of inter-well correlation and analysis of seismic data in the Upper Jurassic stratigraphic interval, as well as the resultsof well data interpretation in the Vogulkinskaya sedimentary rocks within the study area.

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S.V. Vorobyev, P.A. Gorbunov, O.V. Maksimenko, D.Ya. Habibullin. Features of the reservoir pressure changing in oil and gas deposits of the Northern part of the West Siberian oil and gas province

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The arti cle describes features of reservoir pressure changes in the plan and in the secti on of the sedimentary cover in northern part of West Siberian oil and gas province (the territory of Yamal‑Nenets Autonomous District). Authors performed the territory zoning of Yamal‑Nenets Autonomous District describing the changes of reservoir pressures in the secti on and in the area of sedimentary complexes with main hydrocarbon resources. The established zoning is based on the regularity, according to which reservoir pressures in the secti on of the sedimentary cover are approximated by two equati ons. The fi rst equati on is for the upper (Alb‑Cenomanian and Upper‑Neocomian), the second — for the lower (Lower‑Neocomian and Jurassic) parts of the secti on. With help of integrati on of the zoning results and data from prospecti ng and explorati on wells, as well as the materials of seismic studies, a set of 1 : 500 000 isobar maps on the tops of major oil and gas bearing complexes in the north of Western Siberia was built, which was done for the fi rst ti me. These maps can be used to predict reservoir pressures in the perspecti ve areas that are not studied by drilling. Such informati on is necessary for the preliminary assessment of the resources of new oil and gas deposits. Also this data can be used for determinati on of drilling fluids parameters in order to reduce the rate of accidents during the drilling, especially for deep horizons with the abnormally high reservoir pressure. The results obtained by the authors are representi ng interest for geologists who are engaged in planning of geological explorati on, evaluati ng mineral resource base, and also ensuring the safety of explorati on and producti on drilling.

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METHODOLOGY OF PROSPECTING AND EXPLORATION OF OIL AND GAS FIELDS

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V.S. Vorobyev, E.A. Zhukovskaya, Sh.V. Mukhidinov. Consideration of the salinization effect of reservoir rocks B  , B   of the nepa formation in order to improve the exploration drilling efficiency at the Ignyalinsky, Tympuchikanskiy and Vakunayskiy licence areas (Eastern Siberia)

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On the core samples of the Ignyalinskiy, Tympuchikanskiy and Vakunayskiy licence, the comprehensive research program of the Nepskaya suite terrigenous beds was carried out for the first time. For each of the facies, the reservoir quality, mineral and grain composition, the salinization degree of rocks by halite and anhydrite have been determined. The laboratory work results allowed creating the petrophysical model that makes it possible to determine the reservoir quality of rocks, the salinization degree of reservoirs, inflowing intervals of the section. And this serves as the basis for petro-elastic modeling and reservoir’s prediction by the 3D seismic data. Using the detailed analysis of thin sections, the floating cut-off of the inflowing intervals’ allocation was substantiated. The data integration by wells, 3D magnetic exploration and seismic exploration work made it possible to form the main salinization hypothesis and the basic principles of prospecting works and additional reservoir exploration of the Nepskaya suite rocks. Salinization is a secondary process mainly associated with the addition of highly mineralized brines at the catagenesis stage. The source of salts added into the lower section part is the deposits of overlying the Cambrian carbonate-halogen formation. The brines that entered the terrigenous beds spread across the section, pushing out the already existing fluids. The best was the displacement in reservoirs with high reservoir qualities, as well as intervals with water saturation. In purely oil zones, the brine penetration along the faults was limited to 300–500 meters. With a regional reduce of pressure and temperature during the Jurassic-Cretaceous time, settling of salts took place. To minimize the drilling risks, it is recommended to locate exploratory wells in a distance from connecting with under-trappean zones of faults with further movement into the zone affected by the tectonic activity.

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GEOPHYSICAL SURVEYS

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E.A. Kopilevich, N.D. Surova, L.V. Levchuk. Quantative forecast ofreservoir properties of the Gydanskaya and Yenisei-Khatangskaya western part oil and gas bearing areas

 

Quantitative prediction of storage properties of Jurassic and Cretaceous reservoir rocks of the Gydanskaya and western part of the Yenisei-Khatanga oil-and-gas areas obtained by using the technology of combined spectrum-velocity prediction is presented in the article. The physical basis of this technology, its description and the process chart are also presented. Within the scope of this article the use of the technology of combined spectral and velocity prediction for seven reservoirs in the Jurassic – Cretaceous section of the study area is considered. Permeability properties of reservoir rocks of the Gydanskaya and western part of the Yenisei-Khatanga oil-and-gas areas are obtained in the form of prediction maps and cubes of effective thicknesses and specific permeability properties of reservoir rocks. Comparison between the cube sections and prediction maps of effective thickness of respective section intervals is also shown. The obtained cube of effective thicknesses can be used in the 3D statistical model for basin modeling and resources calculation by volumetric method. Based on all the maps obtained the quantitative assessment of hydrocarbon potential has been updated for the western part of the Yenisei-Khatanga regional deep. The obtained prediction maps and cubes of permeability properties allowed for essentially updating of the prediction parameter (Hef) for determination of the analogy factor between the specified calculated and reference blocks when assessing resources potential by the internal geological analogy method.

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HC HARD-TO-RECOVER RESERVES AND UNCONVENTIONAL SOURCES

 

M.Yu. Zubkov. Mineral composition and the δ13C value in fractured carbonate rocks of the Bazhenov-Abalakskaya sequence of West Siberia

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Some concepts on the mechanisms of formation of fractured carbonate rocks forming part of the Bazhenov and Abalakskaya suites in West Siberia are considered. Isotope compositions of the Bazhenov suite bitumen, carbonate bivalve shells and belemnite rostra were determined, as well as mineral and isotope compositions of fractured carbonate rocks. The obtained results have shown that the carbonate rocks with fractures filled with carbonates of several generations have epigenetic (tectonic-hydrothermal), not diagenetic (syneresis cracks) origin. Carbonate deposits forming part of the Bazhenov-Abalakskaya sequence were formed largely at the expense of biogenic carbon dioxide produced by microbial decomposition of organic matter. The carbon dioxide then interacted with sea silt water and was transformed into the carbonate-ion which entered into the composition of these carbonate compounds. The proportion of biogenic light carbon in the carbonate rocks is shown to regularly increase from the periphery of the West Siberian sedimentary basin to its central part. The anomalous enrichment of the of Upper Jurassic marine organisms shells (bivalves and belemnites) with the heavy isotope of carbon owing to fractionation or conservation of its light isotope in the organic matter accumulating in the anoxic silt environments of an epicontinental marine basin, such as the Bazhenov paleo-sea, and in the coeval carbonate sediments also enriched in the "light" isotope of biogenic carbon. The deficiency of the light carbon isotope in the initial lipid part of marine organisms, as compared to its abundance in the bitumen present in the Bazhenov-Abalakskaya sequence, permits to assume that, in addition to the initial organic matter, hydrothermal fluids containing methane have participated in their origin (methane is known to have the lightest isotopic composition of carbon). The methodology for evaluation of oil prospects in carbonate deposits based on all the litho-geochemical data using the carbon isotope analysis is substantiated.

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R.N. Gatiyatullin, S.E. Vojtovich, K.A. Sukhov, A.Z. Akhmetshin.  Localization of occurrence zones of super-viscous oil resources in poorly studied areas of the Melekesskian depression

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Oil potenti al of the Permian deposits in poorly studied areas of the Melekesskian depression is evaluated in the article. For this purpose the authors have compiled and analyzed a considerable amount of actual materials which permitted to prepare structural maps, lithofacies maps, geological sections, etc. As a result of performance of these geological studies four places for drilling prospecti ng and appraisal wells were justifiably pinpointed. The results of drilling and testing of producti ve layers aft er the reservoir stimulati on with steam heati ng have confirmed oil productivity of the Permian deposits. The total initial in‑place and recoverable super‑viscous oil resources of the study area were esti mated, and reserves of the preliminarily assessed accumulati ons were calculated. Based on the combined geological and geophysical informati on the authors have identified four blocks recommended for explorati on for super‑viscous oil pools. For further geological explorati on acti vity the authors recommend to perform detailed geophysical studies (seismic, electrical prospecti ng, etc.) and geochemical surveys using more dense networks of observati on within the blocks recommended for licensing. Besides, the experience in completi on Wells 1–B, 2–B, 3–З and 4–З has permitt ed to conclude that the flow stimulation technology used in low‑permeability reservoirs saturated with abnormally viscous oil is imperfect, and to improve the well testing technology it is necessary to carry out experimental and methodological investigations.

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DISCUSSIONS

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R.B. Seyful-Mulyukov. Oil and gas formation. Theory and practical aspects

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Almost 70 years the paradigm on the organic petroleum origin dominates among petroleum geologists and geochemists. The idea on existence of source rocks is the base for the petroleum commercial accumulations exploration. Author started from Mendeleev and Kudryavchev idea on inorganic petroleum nature. Applying informatics, thermodynamic and biosphere development laws it substituted that organic matter has no any relation with petroleum generation. The data given in paper shows that petroleum is a natural complex system created as a result of hydrocarbon molecules self-organization. Petroleum is the complexity phenomenon that developed in Earth’s interior. The objects are micro level agents — carbon and hydrogen atoms. They are transforming to hydrocarbon molecules under quantum mechanism and catalytic reaction between molecules itself and with atoms the crystal of the minerals. Petroleum origin, composition and age could be cognized according to informatics laws and the generation process applying thermodynamics, geology and geochemistry laws. Since the main micro level objects feature is uncertainty when the petroleum accumulation exploration is the removal of both static and dynamic uncertainty. Their nature is considered and the existing technology and methods of their removal are described..

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INFORMATION

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The list of articles, published in scientific-technical journal "Oil and gas geology" in 2017