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Date submitted2024-05-15
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Date accepted2025-01-28
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Date published2025-04-30
Study of changes in the void space of core samples under cyclic loading
The subsurface state is explored and analysed by studying the core material. This is the basis for forecasts, construction and improvement of models. The reservoir properties of rocks obtained from the laboratory study of sample are subject to a system error caused by three main factors: rock selection in the zone of altered stress-strain state, rock removal from the thermobaric conditions of natural occurrence, and the measuring equipment error. A change in the natural stress-strain state of rocks occurs as a result of intervention in the formation system and the entire massif by constructing a well, creating overburden and depression. The rise of the core causes unloading from formation pressure to atmospheric one, natural saturation is lost, temperature conditions change. This affects the reservoir properties and rock injectivity. This study is aimed at investigating changes in the void space of the rock in formation conditions under cyclic loading. Based on the data obtained, a regression forecast of properties is made, excluding external influences. The article describes the results of experiments on multiple loading and unloading of water-saturated sandstone samples by geostatic pressure with precise control of the water displaced and returned to the void space. This method enables us to record the change in the internal void volume of the rock and, as a consequence, elastic and plastic deformations, the value of relaxation of elastic deformations. The dynamics of change in the coefficients of porosity and compressibility from the stress state cycle is estimated and the range of predicted porosity values of the rock in formation conditions is determined. For samples of permeable medium- to fine-grained sandstone, the obtained character of porosity change gives a forecast of the initial porosity in formation conditions of 20.19±0.61 %. Thus, the exclusion of human impact on porosity gives values 1.42 % higher than the results of standard laboratory studies.
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Date submitted2022-10-04
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Date accepted2024-03-05
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Date published2024-08-26
Localization and involvement in development of residual recoverable reserves of a multilayer oil field
During waterflooding of a multilayer oil field there is a constant deterioration of the structure and composition of residual reserves due to geological and technological reasons. The largest share of residual reserves is localized in pillars, which arise from uneven development of the production facility and are undrained or poorly drained zones. The results of a quantitative assessment of the distribution of residual oil reserves in the Middle and Upper Devonian deposits of the Romashkinskoe oil field of the Republic of Tatarstan are presented. A retrospective method is proposed to identify reserves by analyzing and summarizing historical exploration data and the long history of reservoir development, and a calculation algorithm is proposed to quantify them. It has been established that residual oil reserves are localized in rows of dividing and injection wells, as well as in the central rows of producing wells in a three-line drive, in abandoned and piezometric wells, in the areas adjacent to the zones of reservoir confluence, pinch-out, oil-bearing contours, distribution of reservoirs with deteriorated porosity and permeability properties. Depending on geological conditions, algorithms for selecting geological and technical measures to include localized reserves in development and forecasting production profiles were proposed. According to the proposed method, residual recoverable reserves were identified and a number of wells were recommended for experimental works on their additional recovery: in well 16 (hereinafter in the text, conventional well numbers are used) after isolation of overlying high-water-cut formations, the additional perforation was carried out and oil flow was obtained. Additional perforation in well 6 resulted in oil recovery during development as well. Thus, the developed approaches to identifying residual recoverable reserves and patterns of their spatial distribution can be recommended in other multilayer oil fields with a long history of development.
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Date submitted2022-08-01
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Date accepted2022-11-17
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Date published2023-02-27
Use of machine learning technology to model the distribution of lithotypes in the Permo-Carboniferous oil deposit of the Usinskoye field
- Authors:
- Denis V. Potekhin
- Sergei V. Galkin
Permo-Carboniferous oil deposit of the Usinskoye field is characterized by an extremely complex type of the void space with intense cross-sectional distribution of cavernous and fractured rock. In this study, for this production site, the process of 3D geological modeling has been implemented. At the first stage, it provided for automated identification of reservoir volumes by comparing the data of core and well logging surveys; at the second stage, identification of rock lithotypes according to Dunham classification is performed on the basis of comparison of thin sections examination and well logging data. A large array of factual information enables the use of machine learning technology on the basis of Levenberg – Marquardt neural network apparatus toward achievement of our research goals. The prediction algorithms of reservoir and rock lithotype identification using well logging methods obtained on the basis of the training samples are applied to the wells without core sampling. The implemented approach enabled complementing the 3D geological model with information about rock permeability and porosity, taking into account the structural features of the identified lithotypes. For the Permo-Carboniferous oil deposit of the Usinskoye field, the volumetric zoning of the distribution of different rock lithotypes has been established. Taking into account the lithotypes identified based on machine learning algorithms, density and openness of fractures were determined, and fracture permeability in the deposit volume was calculated. In general, during the implementation, the machine learning errors remained within 3-5 %, which suggests reliability of the obtained predictive solutions. The results of the research are incorporated in the existing 3D digital geological and process model of the deposit under study.
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Date submitted2022-01-31
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Date accepted2022-09-06
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Date published2022-11-10
Filtration studies on cores and sand packed tubes from the Urengoy field for determining the efficiency of simultaneous water and gas injection on formation when extracting condensate from low-pressure reservoirs and oil from oil rims
- Authors:
- Nikolay A. Drozdov
Oil rims as well as gas condensate reservoirs of Russia's largest Urengoy field are developed by depletion drive without formation pressure maintenance, which has led to serious complications in production of oil, gas and condensate. In addition, field development by depletion drive results in low values of oil and condensate recovery. These problems are also relevant for other oil and gas condensate fields. One of the possible solutions is simultaneous water and gas injection. Rational values of gas content in the mixture for affecting gas condensate fields and oil rims of oil and gas condensate fields should be selected using the data of filtration studies on core models. The article presents the results of filtration experiments on displacement of condensate and oil by water, gas and water-gas mixtures when simulating the conditions of the Urengoy field. Simultaneous water and gas injection showed good results in the experiments on displacement of condensate, residual gas and oil. It has been ascertained that water-gas mixtures with low gas content (10-20 %) have a better oil-displacement ability (9.5-13.5 % higher) than water. An experiment using a composite linear reservoir model from cemented core material, as regards the main characteristics of oil displacement, gave the same results as filtration experiments with sand packed tubes and demonstrated a high efficiency of simultaneous water and gas injection as a method of increasing oil recovery at oil and gas condensate fields.
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Date submitted2021-09-16
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Date accepted2022-02-24
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Date published2022-04-29
Production of microfluidic chips from polydimethylsiloxane with a milled channeled surface for modeling oil recovery during porous rock waterflooding
Microfluidic chips with porous structures are used to study the flow of oil-containing emulsion in the rock. Such chips can be made from polydimethylsiloxane by casting into a master mold. At the initial stages of research, fast and cheap prototyping of a large number of different master molds is often required. It is proposed to use milling to make a channeled surface on a polymethyl methacrylate plate, from which a negative image should be taken, which is the master mold for casting positive polydimethylsiloxane chips in it. Several epoxy compositions have been tested to make this master mold. The main requirement in the search for the material was the exact replication of the geometry and sufficiently low adhesion to polymethyl methacrylate and polydimethylsiloxane for removing the product with minimal damage to the mold. It was possible to make master molds from all the materials used, but with defects and various degrees of damage. One of the epoxy compositions was found suitable for making a master mold with many elements simulating the grains of a porous medium (height to width ratio 2:3). The developed method makes it possible to use polydimethylsiloxane for prototyping chips simulating the porous structure of an oil rock.
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Date submitted2019-07-11
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Date accepted2019-08-25
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Date published2019-12-24
Improving the efficiency of using resource base of liquid hydrocarbons in Jurassic deposits of Western Siberia
Under conditions of the same type of oil deposits with hard-to-recover reserves in Jurassic terrigenous reservoirs of the West Siberian oil and gas province, a study was made about the influence of the geological structure features of objects and water flooding technologies on the response degree of production wells to water injection. Response degree of the wells was determined by analyzing the time series of production rates and injection volumes of injection wells with the calculation of inter-correlation function (ICF) values. It was believed that with ICF values in a given injection period of more than 0.5, production well responds to the injection. Factors that have a prevailing effect on water flooding success have been identified. Among them: effective oil-saturated thickness of the formation in production wells; relative amplitude of the self polarization of the formation in both production and injection wells; grittiness coefficient of the formation in injection wells; monthly volume of water injection and distance between wells. Methodological approach is proposed based on the application of the proposed empirical parameter of water flooding success, which involves the use of indirect data in conditions of limited information about the processes occurring in the formation at justification and selection of production wells for transferring them to injection during focal flooding; drilling of additional production and injection wells – compaction of the well grid; shutdown of injection and production wells; use of a transit wells stock; use of cyclic, non-stationary flooding in order to change the direction of filtration flows; determining the design of dual-purpose L-shaped wells (determining length of the horizontal part); limitation of flow rate in highly flooded wells with a high degree of interaction; determination of decompression zones (without injection of indicators), stagnant zones for drilling sidetracks, improving the location of production and injection wells, transferring wells from other horizons; choosing the purpose of the wells during implementation of the selective water flooding system in order to increase the efficiency of using the resource base of liquid hydrocarbons.
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Date submitted2019-01-01
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Date accepted2019-03-03
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Date published2019-06-25
Strategic approach to assessing economic sustainability objects of mineral resources sector of Russia
The article gives a new definition of economic systems (ES) stability with its distinct strategic content. The main approaches to assessment of sustainability, based on the use of strategic cards, including Balanced Scorecard (BSC), are considered. Synchronous management of effectiveness, risks and chances of the ES exhausts the agenda of managing economic sustainability of ES when it operates in the face of a wide range of challenges. BSC in mineral resources sector (MRS) can be built during the aggregation of BSC by industry and individual enterprises. The use of 4 ´ 6 matrix formalism is proposed as the main tool for modeling economic sustainability of the ES.
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Date submitted2018-01-01
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Date accepted2018-03-24
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Date published2018-06-22
Complex petrophysical correction in the adaptation of geological hydrodynamic models (on the example of Visean pool of Gondyrev oil field)
- Authors:
- V. A. Repina
- V. I. Galkin
- S. V. Galkin
The authors review a method of combined porosity and volume density correction in the process of modeling the distribution of reservoir permeability. Basing on petrophysical investigations of core samples from Bashkir fold deposits, an association between rock porosity, density and permeability has been analyzed. Significant correlation has been observed for the above mentioned parameters in porous collectors in contrast to reduced correlation for dense rocks and intervals of anomalously high poroperm characteristics. For terrigene porous collectors the authors propose a model of permeability assessment based on combined porosity and density correction. A modified model was developed for Visean pool of Gondyrev oil field, where collector permeability had been calculated as a function of rock porosity and density. The modified model has been compared to the conventional one; significant differences have been detected. In the modified version maximum permeability is associated with the southern part of the pool, whereas the conventional method points out the central part and predicts lowering permeability closer to the periphery. Geological model in the modified version is more homogenous than the conventional one and has no sharp peaks and valleys. The calculations have been made that reproduce the history of field development for both permeability volumes. Authors demonstrate that total oil production obtained using the modified model has a much better correlation with the actual data. The best results from using suggested method apply to the initial stage of development due to better convergence of high-rate wells. On the whole, comparison of two methods shows that for the purposes of production history adaptation the modified model is significantly better than the conventional one. Hence, the method of density correction allows for better justification of differences in the lithology of Visean collectors, which ultimately results in higher accuracy of data on residual oil reserves in the deposit.
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Date submitted2016-11-21
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Date accepted2017-01-23
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Date published2017-04-14
Prospects of obtaining samples of bottom sediments from subglacial lake Vostok
- Authors:
- N. I. Vasilev
- G. L. Leichenkov
- E. A. Zagrivnyi
The paper proves the timeliness of obtaining and examining bottom sediments from subglacial Lake Vostok. Predictive geological section of Lake Vostok and information value of bottom sediments have been examined. Severe requirements towards environmental security of lake examinations and sampling of bottom sediments rule out the use of conventional drilling technologies, as they would pollute the lake with injection liquid from the borehole. In order to carry out sampling of bottom sediments from the subglacial lake, it is proposed to use a dynamically balanced tool string, which enables rotary drilling without any external support on borehole walls to transmit counter torque. A theoretical analysis has been carried out to assess the operation of the tool string, which is a two-mass oscillatory electromechanical system of reciprocating and rotating motion (RRM) with two degrees of freedom.
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Date submitted2015-08-21
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Date accepted2015-10-24
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Date published2016-04-22
Results of the 5G borehole drilling at russian antarctic station «Vostok» and researches of ice cores
- Authors:
- N. I. Vasilev
- A. N. Dmitriev
- V. Ya. Lipenkov
We produce an information about results and features of the 5G borehole drilling in Antarctic layer at Russian station Vostok. Main regularities of the change structured and physical properties by Antarctic ice layer depth, which determine mechanical and reological properties if ice, which influence to sinking of a borehole and to the maintaining of it in a working condition, the safe and competitive technologies creation for drilling of strong ice layers and the environmentally safe technology of the subglacial reservoirs unsealing. We also produce results of the ice cores researching and the paleoclimatic raws construction, which are reconstructed by the ice cores researching from Vostok station, which is compared with isotopic graph. This graph describes changes of World ocean level.
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Date submitted2015-07-05
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Date accepted2015-09-01
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Date published2016-02-24
Substantiation of intrastratal water shutoff technology in low permeability reservoirs
- Authors:
- M. K. Rogachev
- A. O. Kondrashev
The article presents the results of the filtration tests of the developed polymeric waterproofing compound GPS-1, which is a mixture of a water-alkaline hydrolyzed acryl-containing polymer solution with a nonionic surfactant. The obtained results indicate significant improvements of main operational parameters – penetrating and water-insulating power of the developed polymeric composition GPS-1 in comparison with the original one: addition of the nonionic surfactant reduced the pressure gradient of injection twice. Also, considerable (5 times) increase of the residual resistance factor, that is explained by deeper and more uniform penetration of the solution into the porous medium and the corresponding raise of isolation efficiency of pore channels, is established. Experiments on the model of a heterogeneous oil-filled formation showed that after the injection of the polymeric solution water mobility decreases in a highly porous interlayer and increases in a low-permeability interlayer indicating a redistribution of filtration flows in the model of a heterogeneous bed. The decrease of water mobility in a high-permeability zone contributes to the leveling of the displacement front and, ultimately, the additional extraction of oil from the less permeable area. As a result of the complex of filtration tests conducted, the efficiency of the developed polymeric composition GPS-1 for the regulation of filtration flows in low-permeability heterogeneous reservoirs is proved.
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Date submitted2014-11-07
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Date accepted2015-01-07
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Date published2015-10-26
The concept of reducing the risks of potash mines flooding caused by groundwater inrush into excavations
- Authors:
- V. P. Zubov
- A. D. Smychnik
Results of the analysis of factors influencing the probability of accidental groundwater inrush into mine workings of salt (potash, potassium and magnesium) mines are given in the article. The cases of the potash mine flooding that occurred in different countries with developed mining industry are given. It is shown that at the present technical and scientific level of solving this problem the unexpected groundwater inrush in potash mines usually results in the shutdown of the enterprise and negative ecological consequences. It is pointed out that the underground waters flow into the mines through water-conducting fractures of either natural or technogenic origin which location and influence on a mine was almost impossible to predict at the design stage under existing regulations. The concept of reducing the risks of potash mine flooding caused by underground waters in-rush is formulated. Administrative and technical measures which allow reducing the risks of potash mine flooding caused by groundwater inrush into the excavations are considered.
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Date submitted2009-09-08
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Date accepted2009-11-15
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Date published2010-06-25
Some peculiarities of english for specific purposes course development
- Authors:
- I. S. Lebedeva
The paper involved deals with the challenge Russian system of higher education faces. Special attention is paid to the core principles of ESP course development.
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Date submitted2009-09-27
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Date accepted2009-11-18
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Date published2010-06-25
Environmental problems оf waste water utilization at gas field development
One of the main factors of environment contamination on the gas industry ventures is waste water. To improve the ecological situation at gas fields the joint purification, treatment and flooding of associated liquid, industrial and domestic waste water into lost circulation horizons is proposed.
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Date submitted2009-07-17
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Date accepted2009-09-06
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Date published2010-04-22
Hydrogeomechanical processes in flooding of mines
- Authors:
- Yu. A. Norvatov
- I. B. Petrova
Hydrodynamic and hydrogeomechanical processes which may occur during flooding of coal mines are considered. Original scheme – model of strain state of waterbearing undermined massif for estimation of uplift of earth surface was suggested.
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Date submitted2008-10-11
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Date accepted2008-12-19
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Date published2009-12-11
The development of the effective method for sampling of native-state core in natural gashydrate deposits
- Authors:
- V. K. Chistyakov
Gas hydrates – the firm crystal connections of water and low-molecular waterproof natural gases such as carbohydrates (mainly methane), СО 2 , N 2 and others. At present, time exploitation of the Messoyahsk (Russia) and Mallik (Canada) deposits of gas hydrates is conducted actively. The further perfection of prospecting methods in the field of studying gas hydrate containing sediments in round extent depends on improvement of methods for native-state core sampling from these sediments.
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Date submitted2008-10-16
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Date accepted2008-12-24
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Date published2009-12-11
Procedures and techniques for operation of the new automatic core orientator
- Authors:
- Yu. T. Morozov
The most similar prototype models of foreign and domestic core orientators have been analyzed, and a model of a new automatic core orientator created by the author is presented. It provides continuous drawing of three lines on1,5 metercore surface section by diamond cutters in borehole drilling, secures accurate core orientation, decrease in time and general costs of this work.