Articles

Geology

Evaluation of reservoir saturation and unrecovered reserves localization by pulse-code interference testing

Volkov Yu.V., Mingaraev R.A., Fatkulin M.R., Khaziev R.R., Andreeva E.E., Zinurov L.A.

DOI: 10.24412/2076-6785-2021-5-35-39

Abstract
In this paper, the method of pulse-code testing (PCT) on one of the squares of the fields of the Volga-Ural province to assess localized reserves of hydrocarbons (HC) and the feasibility of workovers and sidetracking to increase ultimate recovery up to value at field development plan. During the PCT, the following tasks were solved: the residual hydrocarbon reserves in the study area were estimated; the forecast indicators of liquid and oil after the sidetracking were calculated; the influence of the generator well Y1 on the surrounding wells was estimated.

Materials and methods
During PCT surveillance, downhole pressures were recorded at wells using zPas-20M quartz pressure gauges (with a resolution of 20 Pa) which is based on a temperature-stabilized quartz crystal. Furthermore, water injection rate of the injection well was measured using a portable flow meter. PCT is based on the Pulse-Code Decomposition (PCD) algorithms
a procedure for decomposing complex pressure responses at each well into different components, where each component correlates with the flow rate changes history of only one particular generating well.

Keywords
well testing, interference test, oil reservoir, transmissibility, diffusivity, reservoir evaluation, reserves localization

The mechanism of the indicator propagation in a terrigenous formation during tracer studies

Izotov A.A., Afonin D.G.

DOI: 10.24412/2076-6785-2021-5-31-34

Abstract
The tracer method of research is used in oil fields in the study of filtration flows in the reservoir. Studies reveal similar phenomena: a high speed of movement of labeled water for a porous medium, an uneven geometry of the distribution of flows over the area of the deposit. This still causes various hypotheses among researchers. Based on the geological and field analysis and research results, the concept of the indicator propagation in a terrigenous formation through technogenic fractures of auto-fracturing is proposed, which removes contradictions and combines hypotheses and facts. A method for calculating the parameters of cracks for the purpose of planning insulation works is proposed.

Materials and methods
Materials: analytical database, monthly operational reports on the deposits of the Russian Federation. Methods: geological and commercial analysis, graphical representation
of dependencies.


Keywords
tracer studies, flooding, waterlogging, auto-hydraulic fracturing

Forecast oil content of sakmarian sediments in the east side of Tatarstan Republic according to study core matherial of bio-testing wells

Khaziev R.R., Anisimova L.Z., Baranova A.G.

DOI: 10.24412/2076-6785-2021-5-24-27

Abstract
The trend of annually increasing oil production in the Volga-Ural oil and gas province requires increasing the mineral resource base by opening new fields or entering into development of hard-to-recover (unconventional) hydrocarbon reserves. One of this alternative sources of hydrocarbons is Permian bitumen, which is concentrated in the ufimian, kazanian and lower permian sediments in the south-east of Tatarstan. Prospects for the discovery of small bituminous deposits are also available in the eastern part of Tatarstan, where positive forecasts for hydrocarbon raw materials for the deposits were obtained according to lithological, tectonic criteria and the results of drilling test wells.

Materials and methods
Theoretical lithological-facies maps of the sakmarian deposits on the Tatarstan Republic. Practical maps with the results of drilling bio-testing wells. Object of research exploration areas on the territory of the eastern slope of the South Tatar arch.

Keywords
super-viscous oils, carbonate reservoir, sakmarian deposits, bio-testing wells, secondary mineralogy

Tectonic history of Beregovoye oil and gas field from the point of view of new geological and geophysical data (history of formation of structural forms of productive reservoirs)

Gorbunov P.A., Lebedev M.V., Yanevits R.B., Fishenko A.N., Dorohov A.R., Abrashov V.N.

DOI: 10.24412/2076-6785-2021-5-17-20

Abstract
This article completes the cycle of studies devoted to the paleotectonics of the Beregovoye field (Yamalo-Nenets Autonomous District). The article presents the results of studying the history of the formation of structural forms of productive reservoirs.

Materials and methods
Materials: the results of the structural interpretation of the seismic volume of the Beregovoye oil and gas field, including the results of structural mapping for the uppermost reflecting horizon E. Methods: Analysis of power maps according to the method of V.B. Neiman.

Keywords
Western Siberia, Beregovoe oil and gas field, tectonics, paleotectonic analysis, productive reservoirs, reflecting horizon E

A comprehensive approach to the efficiency evaluation of a block agent using laboratory core analysis

Kochetov A.V., Usoltsev A.V., Neklesa R.S., Bikmulin R.Z.

DOI: 10.24412/2076-6785-2021-4-40-43

Abstract
The use of a traditional well-killing fluid (water-salt mixture) may lead to a large liquid loss, which causes the increase in the amount of chemicals needed for operation, time expenditures and consequently the overall price of work.
In this study a series of formation damage tests were performed on core samples from Cenomanian formation at reservoir conditions in order to collect data about the effectiveness of several modern block agents presented on the market. The parameter of the fluid intake capacity, which defines the invasion zone characteristics of the near-wellbore formation, was examined for the purpose of a more consistent and complete analysis of the research data.
As a result: two block agents (Gelenix and MEX BLOCK) had low value of the fluid intake during the expose period (80 hours) and high value of the formation damage coefficient. That makes these two-block agent the most effective among the tested process fluids.


Materials and methods
Materials: rock (core samples) from Cenomanian formation, wellkilling brines, block agents (based on gelling fluids), oil samples from Cenomanian formation. Methods: the measurement of swelling capacity of oil-saturated / watersaturated samples, formation damage tests on block agents.

Keywords
block agents, core samples, permeability, formation damage coefficient, fluid intake capacity, oil saturation

Estimating minimum miscibility pressure and minimum oil swelling when displaced by associated petroleum gas for the conditions of an East Siberian field

Kobyashev A.V., Pyatkov A.A., Zakharenko V.A., Gromova E.A., Dolgov I.A.

DOI: 10.24412/2076-6785-2021-4-35-38

Abstract
A case study of the Severo-Danilovskoye field in East Siberia is presented to describe an experimental measurement of miscibility between oil and injected gas. The minimum miscibility pressure and the minimum oil swelling by associated petroleum gas are estimated. The slim tube displacement efficiency as a function of gas enrichment with C2C4 components is obtained. An approach to planning displacement conditions in a slim tube using correlations and an equation of state is presented.

Materials and methods
Materials: results of slim tube oil-gas displacement evaluation of the Severo-Danilovskoye field in East Siberia. Methods: estimation of the minimum miscibility pressure using Maklavani correlation and the state equation.

Keywords
minimum miscibility pressure, minimum oil swelling, equation of state, gas injection efficiency

The influence of tectonic processes on HC deposits formation at the Vankor cluster

Fateeva E.V., Buyakina I.V., Kantemirova N.A.

DOI: 10.24412/2076-6785-2021-4-30-33

Abstract
The influence of tectonic processes on the formation of hydrocarbon traps is studied on the example of the Vankor cluster. Geological and geophysical materials, as well as the difference in fluid contacts were analyzed to study paleotectonic activity, the periods of structures development intensity and to understand the features of structural and tectonic formation of hydrocarbon traps within the Lodochnoye Val. The presence of tectonically stressed zones within the Lodochnoye field and at the edges of Tagulskoye Lodochnoye Vankor uplifts has been confirmed.

Materials and methods
Materials: seismic data on the Vankor cluster, interpretation of logging data in the Lodochnoye field wells. Methods: maps, graphic images of structures depths vs. formation
period.

Keywords
paleotectonic analysis, separation zones, fluid contact levels, structures development, the Lodochnoye field

Tectonic history of Beregovoye oil and gas field from the point of view of new geological and geophysical data (history of tectonic development)

Gorbunov P.A., Lebedev M.V., Yanevits R.B., Fishenko A.N., Dorohov A.R., Abrashov V.N.

DOI: 10.24412/2076-6785-2021-4-24-28

Abstract
This article continues the cycle of studies devoted to the paleotectonics of the Beregovoye field (Yamalo-Nenets Autonomous District). The article presents the results of studying the history of tectonic development of the field.

Materials and methods
Materials: the results of the structural interpretation of the seismic volume of the Beregovoye oil and gas field, including the results of structural mapping for the uppermost reflecting horizon E. Methods: analysis of power maps according to the method of V.B. Neiman.

Key words
Western Siberia, Beregovoye oil and gas field, tectonics, paleotectonic analysis, reflecting horizon E

Tectonic history of Beregovoye oil and gas field from the point of view of new geological and geophysical data (seismogeological cross section)

Gorbunov P.A., Lebedev M.V., Yanevits R.B., Fishenko A.N., Dorohov A.R., Abrashov V.N.

DOI: 10.24412/2076-6785-2021-4-20-23

Abstract
This article opens a series of studies devoted to the paleotectonics of the Beregovoye oil and gas field (Yamalo-Nenets Autonomous District). The article provides general information about the object, as well as the characteristics of the seismic-geological cross section of the field.

Materials and methods
Materials: the results of the structural interpretation of the seismic volume of the Beregovoye oil and gas field, including the results of structural mapping for the uppermost reflecting horizon E. Methods: Stratigraphic well tie and correlation of seismic reflections, analysis of the structure of reflecting horizons.

Key words
Western Siberia, Beregovoye oil and gas field, tectonics, paleotectonics, seismogeological cross section, reflecting horizon E

Assessment of the generation potential of the bazhenov formation in the Khanty-Mansiysk autonomous okrug

Fedorova E.V.

DOI: 10.24412/2076-6785-2021-4-16-18

Abstract
The article studies and describes information about the features of the bazhenov formation. On the basis of the PetroMod software package, models were built that reflect the generation capabilities of the bazhenov formation in the Khanty-Mansiysk autonomous okrug, the corresponding conclusions about the prospects of the considered area.

Materials and methods
Vostochno-Surgutskoye field, basin analysis, PetroMod software.

Keywords
Bazhenov formation, Khanty-Mansi autonomous okrug, PetroMod, generation potential

Hydrocarbon systems and combined traps of the lower-middle jurassic deposits of the northern regions of Western Siberia

Punanova S.A.

DOI: 10.24412/2076-6785-2021-3-22-27

Abstract
The features of oil and gas complexes (OGC) of the lower-middle jurassic deposits of the Nadym-Taz region in the north of the West Siberian oil and gas basin (OGB) and the confinement of accumulations to traps of non-anticlinal structure are considered.The lithological and geochemical characteristics of the deposits are given, the degree of catagenetic transformation of organic matter (OM) is estimated, the accumulations are typified by chemical types and subtypes based on the hydrocarbon composition (HC) and the phase state of HC deposits is predicted. The deposits are differentiated by the amount of geological reserves. The prospects of the lower-middle jurassic deposits are shown.

Materials and methods
Materials: Materials: an analytical database of the properties of oils and condensates of the lower-middle jurassicdeposits of the Nadym-Taz oil and gas region, the stages of catagenetic transformations of OM of rocks, as well as the values of geological reserves. Methods: comparison of lithofacies environments of sedimentation of deposits of an oil and gas complex, cartographic construction, graphical representation of the dependences of geochemical parameters and the size of hydrocarbon accumulations.

Keywords
lower-middle jurassic deposits, traps of non-anticlinal type, forecast of the phase state, oil, condensates, scale of accumulations

The influence of sedimentation conditions on the productivity reservoir rocks kazanian deposits

Khaziev R.R., Mudarisova R.A., Volkov Y.V., Anisimova L.Z.

DOI: 10.24412/2076-6785-2021-3-17-21

Abstract
The trend of increasing oil production in the Volga-Ural oil and gas province requires increasing the mineral resource base by opening new fields or entering into development of hard-to-recover (unconventional) hydrocarbon reserves. In Tatarstan Republic, natural bitumen (NB) and superviscous oils (SVO) of the Kazanian stage are unconventional, which are not currently involved in development. SVO deposits in Kazanian stage sediments are usually a set of deposits confined to mainly carbonate reservoirs, representing a complex reservoir in terms of reserve development. One of these deposit is the Gorskoye SVO field, located on the Eastern side of the Melekess Depression, on the border of the Tatarstan Republic and the Samara Region. In present work, a lithological and facies analysis kazanian-age sediments was carried out based on the core material data. The most promising areas of reserves development are identified according to the data of the lithological description of the core material.

Materials and methods
Theoretical: lithological and facial maps of Kazanian sediments in the territory of Tatarstan; the concept of lithofacial analysis. Practical: tabular data with a detailed description of the core material from the exploratory wells within the Gorsky field, photos of the Kazan sediment sections.

Keywords
facies analysis, syper-viscous oils, carbonate reservoir, filtrationcapacitance properties, imposed epigenesist

On some features of the structure of the tournaisian deposits on uplifts with visean-age cuts

Arefyev Yu.M., Andreeva E.E., Baranova A.G., Ionov G.M.

DOI: 10.24412/2076-6785-2021-3-10-13

Abstract
The article devoted to the problem of reliable estimation of oil reserves of the tournaisian deposits on uplifts with different-depth visean-age cuts. The main purpose of this work: to identify the geological factors that determine the structure of the tournaisian deposits and influence the assessment of their reserves. On the studied uplift, the Tournaisian deposit is an eroded surface of the carbonate deposits of the kizelovian, cherepet, and upino-malevsky horizons, filled with terrigenous sand-clay material of the tula-bobrikovsky age, containing oil-saturated sand layers that most likely have a hydrodynamic connection with the main tournaisian deposit.

Materials and methods
Studying a structural map fragment of the West-Rakashev local uplift, well logging curves and logging conclusions for lower carboniferousage productive sediments; geological profile of lower carboniferous deposits on the studied local uplift.

Keywords
tournaisian deposits, Melekess depression, oil deposit, visean-ag cuts, carbonate reservoir

Fracturing of siliceous clayey rocks of the NB1 formation of the Berezovskaya suite in the central part of Western Siberia

Kalabin A.A., Chertina K.N., Nassonova N.V., Deviatka N.P.

DOI: 10.24412/2076-6785-2021-1-30-33


Abstract
Currently, the Rosneft Oil Company is implementing an innovative project to develop technologies for the study and development of unconventional gas facility in the sediments of the Berezovskaya suite in Western Siberia. Deposits of the target formation NB1, with which the main prospects are associated, are represented by a porous-fractured reservoir type. This article contains detailed description of the properties and parameters of the genetic fractures in the NB1 formation which can be used as an analog in the similar type reservoirs. The methodology used in this article combines several different multi-scale approaches to the fractures study: from a macro description
of the core to the high resolution methods like mineral composition of the near-fracture space by the X-ray fluorescence analysis and REM method of thin sections made through the cracks identified on the core.

Materials and methods
Macro description of core material, classification of fractures by genetic characteristics, determination of fracture space parameters, X-ray fluorescence analysis, X-ray energy-dispersive microanalyzer, stage analysis.

Keywords
Berezovskaya Formation, siliceous-clayey deposits, unconventional reservoir type, macro-fracturing, micro-fracturing, tectonic fractures, cleavage, near-fault fractures, lithogenetic fractures, syneresis, reservoir model

Influence of mineral composition of rocks and isotopic composition of formation water on the high content of hydrogen sulfide in the production on the example of oil deposit in isolated reef bioherm in the eastern part of the Rubezhinsky trough

Shipaeva M.S., Morozov V.P., Sergeeva E.V., Kirillov A.S., Sobolev V.I., Sereda I.A.

DOI: 10.24412/2076-6785-2021-1-24-29

Abstract
The reasons for the high content of sulfur compounds in the oil production of reef deposits of the Frasnian stage were identified basing on complex analysis of geological and production data, core study, formation fluid studies, and isotopic composition of formation water. Secondary alterations: dolomitization and sulphatization in carbonate rocks are the reason of different content of hydrogen sulfide in reservoir fluids.

Materials and methods
An integrated approach based on petrographic studies of rocks and geochemical studies of formation fluids (oil, gas, water).

Keywords
hydrogen sulfide, oil, deposits, carbonate reservoir, secondary changes

Pilot area as a key to successful development of hard-to-recover reserves

Tkachenko E.I., Shirokov A.S., Grandov D.V., Eremin S.A., Taylakov P.I.

DOI: 10.24412/2076-6785-2021-1-19-22

Abstract
The design solutions for large and unique fields are often hard to justify due to fact that the reserves development becomes efficient in various parts of continuous reservoirs (pure oil-zones/gas-oil-water zones, monolithic/compartmentalized reservoir) only when using differentiated approaches (well pattern/type of well completion, presence or absence of bottomhole zone stimulation). At the initial stage of development, the limited amount of reliable field information introduces significant uncertainty in the estimates, even in short-term planning. Thus, in the period preceding the full-scale development of large fields, especially those containing hard-to-recover reserves,
pilot areas should be selected to test and confirm the theoretical research. This study describes the results of extended pilot operations carried out in PK1-7 reservoir of the Russkoye oil and gas condensate field in the
period from 2007 to 2014 to prepare it for commercial development.

Material and methods
Based on the actual field information and flow simulation data, a comparative analysis of well operation results was made which was used to form the main design solutions on developing a field with hard-to-recover reserves.

Keywords
pilot development, hard-to-recover reserves, high-viscosity oil, cenomanian, horizontal wells, multilateral wells

Influence of the nature of the saturating agent on the elastic-strength properties of gas field rocks

Pavlov V.A., Kuleshov V.S., Kudymov A.Yu., Yakubovskiy A.S., Subbotin M.D., Ptashnyy A.V., Abzgildin R.R., Maksimov E.V.

DOI: 10.24412/2076-6785-2021-1-11-16

Abstract
The existing laboratory methods for determining the elastic-strength properties of a weakly consolidated core were adapted, including laboratory pre-saturation of samples with various fluids, as well as while creating pore pressure with gas. The influence of saturating agents on the elasticstrength properties of gas field core samples is studied. Liquids (natural saturation, water, kerosene) and gas (nitrogen) were considered as saturating agents. It was found that, depending on the nature of the saturating agent, changes in the values of the static Youngs modulus, determined during volumetric compression, reach 30 %; the Poissons ratio 10 %. It is shown that when the core sample is saturated with water, the value of the uniaxial compressive strength decreases by 24 times, and the Youngs modulus decreases by an average of two times in comparison with the natural saturation of the sample.

Material and methods
Based on the method of preliminary rapid freezing of the rock in liquid nitrogen, core samples are drilled from weakly consolidated rock. Additionally, a tomography is used to monitor the quality and integrity of the obtained core samples. Additional saturation of core samples with kerosene or water is performed by liquid pump lines system connected to the core holder. In the case of additional nitrogen saturation of the samples, a gas cylinder is connected to the pore pressure line through the reducer. Laboratory studies were carried out to determine the elastic-strength properties of the rock at different saturation.

Keywords
core analysis, elastic-strength properties, various saturation, geomechanics

Certain aspects of forming extra-viscous oil deposits in sakmarian sediments in the Tatarstan Republic

Khaziev R.R., Andreeva E.E., Anisimova L.Z., Fakhrutdinov I.R., Baranova A.G.

DOI: 10.24411/2076-6785-2020-10114

Abstract
The work considers the peculiarities of the lithological and tectonic structure of the territory of the northeastern part of the South Tatar arch (STA). Favorable factors for formation of hydrocarbon accumulations in the area under study were revealed: presence of anticlinal structures of the first order, presence of fractured and cavernous rocks in sediments of the Lower sakmar stage, presence of rocks-fluid stops in overlying sediments ensuring preservation of potential
oil deposits. In addition, additional prerequisites for the formation of hydrocarbon deposits (HC) were identified: the presence of faults that provide the possibility for vertical migration of HC with the subsequent filling of potential traps;
as well as secondary changes forming the hollow space of rock collectors. The obtained conclusions make it possible to give a favorable forecast during geological exploration for hydrocarbons in Sakmar sediments on the studied territory.

Materials and methods
Theoretical data: maps of the tectonic structure studying territory and the map of modern neotectonic movements of the earth's crust. Field methods: description of core material (both primary according to geological journals, and re-description by a team of authors). Laboratory methods: raster electron microscopy (REM) data of core samples. Object of study: in present work object of research was a core material taken from sakmarian age sediments during exploratory drilling on the territory of the North-Eastern slope of the South-Tatar ark (STA). (In agreement with the subsoil user, data about exploration area, the number of drilled wells, and their sequence numbers are not disclosed.)

Keywords
extra-viscous oils, EVO, carbonate collector, filtration-capacitive properties, FCP, oil reservoir, South Tatar arch, STA, raster electronic microscopy, REM

Lithological and facies features of the lower kazanian sediments according to EPR data on the example of the Gorsky SVO deposit

Mudarisova R.., Uspensky B.V., Volkov Yu.V., Khasanova N.M., Baranova A.G.

DOI: 10.24411/2076-6785-2020-10115

Abstract
In this paper, we consider the heterogeneous structure of carbonate rocks-reservoirs of the middle kazanian age of the Gorsky SVO deposit, tectonically confined to the eastern side of the Melekess Depression, according to paramagnetic marks (PM). The use of the electron paramagnetic resonance (EPR) method for studying carbonate rocks is widespread, as it allows obtaining information about the formation features, heterogeneity of the structure of carbonate rocks, and detailing their structure to solve many problems, including the dismemberment and geological correlation of upper Paleozoic sediments.

Materials and methods
Results of core material bitumen carbonates study of the lowerkazanian stage of the Gorsky Deposit in Tatarstan by electron paramagnetic resonance (EPR).

Keywords
ultra-viscous oils, SVO, heavy oils, kazanian sediments, oil reservoir, bitumen, electronic paramagnetic resonance, EPR

The effect of fault-block tectonics on the structure of oil deposits in upper jurassic anomalous section of the Bazhenov formation on the example of the Tevlinsko-Russkinskoye field

Mitina A.I.

DOI: 10.24411/2076-6785-2020-10119

Abstract
The article explains the nature of formation of the upper Jurassic anomalous sections of the Bazhenov formation as the result of the accumulation of precipitation upon immersion of the individual blocks in considerationem faults with subsequent widespread precipitation accumulation actually Bazhenov formation; reasons for influencing the position of the oil-water contact (OWC) in deposits of anomalous section of the Bazhenov formation; it is determined that deposits in these formations are confined to traps structural type and are controlled, to a greater extent, tectonic dislocation, and not local change in lithology.

Materials and methods
Information on more than 900 wells of the Tevlinsko-russkinsky field that opened up the studied deposits was studied using the following method: selection of the complex of the most informative well log data, stretching and compressing curves; fill in reference intervals bounded by one or two logging cased wells; sequential paleoprophylation with repeated changes in the mapping line to determine whether there are specific changes in the section between two adjacent mapping lines; grouping of wells by section types in order to identify the block structure of the studied deposits; combining correlation schemes with seismic data; the construction of structural maps of the productive strata.

Keywords
correlation of well sections, Bazhenov formation, its anomalous sections, deposits of oil