bluuebunny/crossref_metadata_2025_split huggingface dataset:
Reduction of Accidents During Mine Construction with Geomechanical Modeling
Authors: Melikov Ruslan Fuadovich , Korelskiy Evgeniy Pavlovich , Krasnikov Artem Alexandrovich , Volkov Dmitry Yurievich , Petrakov Yuriy Anatolievich , Sobolev Alexey Evgenievich 
Published: September 2020

Abstract
The uniqueness of this work lies in the application of the approaches and experience of geomechanical modeling accumulated in the oil and gas industry to solve the problems of building mines, which reduced accident rate and, as a result, minimized the cost of eliminating the consequences of complications, as well as accelerating the commissioning of the mine.
The peculiarity of the simulation was to take into account the temperature of the rock mass and freezing wells, which affected the stress state, safe drilling window and cementing parameters during the construction of additional freezing loop wells, as well as during the strengthening of the rock mass.
Based on the results of the well logging, seismic surveys and geomechanical modeling, the stress state of the decompression zone is estimated and the parameters of the cement slurry injection when attaching wells and strengthening the rock mass to isolate the shaft from aquifers are recommended.
Usage of Imitational Geological-Petrophysical Models to Reduce Drilling Risks for Offshore Reservoirs Exploration
Authors: Dubinya Nikita Vladislavovich , Vershinin Anatoly Viktorovich , Pirogova Anastasia Sergeevna , Tikhotsky Sergey Andreevich 
Published: September 2020

Abstract
The paper presents the results of numerical modeling of the stress fields acting in hydrocarbon reservoirs located at Russian continental shelf. The problem of prediction of the zones with the higher drilling risks based on the detailed analysis of seismic data is considered. We focus on the problem of the degree of the influence some factors have on zones of potential drilling risks. These factors include: dependencies between static and dynamic elastic moduli and strength properties; parameters standing for pore pressure distribution and tectonic stresses. Imitational geological-petrophysical models are used as a tool for such analysis. Those are models of mechanical properties, complemented with pore pressure fields and tectonic forces. The dynamic characteristics of seismic data (amplitudes and frequencies) obtained from high quality seismic data interpretation act as a basis for construction of imitational models. The paper describes the creation of such models, the main parameters used for variation of considered factors are highlighted, imitational models are created based on seismic data obtained at Laptev sea shelf. Numerical geomechanical modeling is carried out for these models, quantitative drilling risks analysis is performed with prediction of the zones of potential drilling risks. The problem of possible potential drilling zones prediction based on seismic data interpretation results systematic analysis is discussed.
3D Digital Mineral-Mechanical Modeling of Complex Reservoirs Rocks for Understanding Fracture Propagation at Microscale
Authors: Nachev Victor Andreevich , Kazak Andrey Vladimirovich , Turuntaev Sergey Borisovich 
Published: September 2020

Abstract
Increasing the efficiency of hydraulic fracturing operations in complex reservoir rocks requires creating an extensive network of fractures to improve the drainage zone of the field development. The research aims at understanding the stress-strain conditions required the initiation and propagation of mechanical fractures during well-bore zone stimulation in tight reservoir rocks. We investigate at the microscale, taking into account the mineral heterogeneity, matrix structure, elastic-plastic properties of minerals, and their intergranular contacts. The research relies on experimental data performed on modern laboratory equipment and the use of applied simulation software. We propose an integral physico-mathematical model of the propagation of three-dimensional fractures at the microscale. The model accounts for the granular composition and structure of the sample, its elastic-plastic properties, and conditions at the intergranular contacts. We discuss a set of experimental methods and research necessary for numerical simulation of fracture propagation at the microscale, taking into account the heterogeneous mineral composition of the reservoir rock. The paper shows the results of mathematical elastic-plastic modeling of stress-strain state and fracture propagation in two-dimensional and three-dimensional models with the complex geometry of contacts between minerals. Finally, we make conclusions about the possibility of using the results obtained in optimizing the parameters of hydraulic fracturing.
Borehole Failures and Stress Regime Identification Challenges in Fractured Carbonates of Boca De Jaruco Field
Authors: Zhekenov Temirlan , Norkina Anna' , Petrashov Oleg , Chettykbayeva Kamilla , Mylnikov Danila , Petrakov Yuriy , Sobolev Alexey 
Published: September 2020

ABSTRACT
This article is continuation of geomechanical estimations for wellbore stability and horizontal wells drilling optimization to M formation of the Boca de Jaruco oilfield, Republic of Cuba. Following the completion of the first part of the work presented in the article SPE-196897-RU, the first horizontal wells were successfully drilled. In the first part of the work, the stress-state analysis and horizontal in-situ stresses directions were analyzed using pressure behavior during steam injections, cross-dipole acoustics, as well as data from oriented caliper from vertical wells. As a result, according to the recommendations, an additional study in the deviated sections of the wells, including core sampling and micro-imager logging were conducted. Presence of wellbore failures at the inclined sections allowed to use the method of inverse in-situ stress modeling based on image logs interpretation. The main result of the work were the determination of the stress state and horizontal stresses direction, as well as classification of the failures detected using the image log into groups. Moreover, the genesis of breakouts which had deviation from each other different that 180° were evaluated.
Selection of Optimal Developing Strategy for A Group of Prospects in Terms of Geological Uncertainties and Infrastructure Constraints
Authors: Legkokonets Vladislav Aleksandrovich , Vasilenko Alexey Aleksandrovich , Khasanov Mars Magnavievich 
Published: September 2020

Abstract
The aim of this work is to create a tool that can help in making difficult investment decisions about the sequence and commissioning periods of new hydrocarbons fields, maximizing expected monetary value and considering infrastructure constraints across a group of assets in terms geological uncertainties.
The approach is to use probabilistic calculations and the modern portfolio theory, adapted to the conditions of the sphere of petroleum exploration and production. The goal of optimization is finding a strategy for new assets development that would have the maximum profit with minimal economic or technological risk. Measures of spread of a random variable (a.g. NPV) around its expected value are used to measure an economic risk. Also, we propose a method of technological risk assessment, reflecting the probability of hydrocarbon production in the required range. To obtain a probability distribution of the objective function according to uncertainties in input data the stochastic Monte-Carlo simulation and "Latin hypercube" technique were used. Due to high dimensionality of the problem, heuristic optimization methods have been used to solve the optimization task.
A proxy model, based on the change in recoverable reserves volumes, starting production rates and decline rates of hydrocarbon production for newly drilled wells is proposed in this paper. The model combined with the calculation of economic measures. The combination of simulation models with an optimization algorithm allows to analyze a set of mathematical equations, containing a number of decision variables (e.g., years of commissioning periods and/or the paces of drilling wells) and to determine their optimum values, leading to a solution with the desired ratios of the expected economic effect and risk value. As a result, the numerical experiment revealed that application of the portfolio optimization methods allows to find new non-obvious solutions. The result of portfolio analysis is not a final product of project works, but, however, may be a basis for explanation of optimal development scenarios for a group of assets and can help in finding non-obvious, but more effective investment and project decisions.
A comparison of four heuristic algorithms in the single-criterion optimization problem was conducted. Conclusions about the effectiveness of the algorithms in terms of time and the fitness function values were made. The developed model and methods were used in task of searching the optimal development strategy for a group of real hydrocarbons fields.
Practical Application of the Geosteering Difficulty Index.
Authors: Kudashov Kirill Valerievich , Filimonov Victor Petrovich , Golovchenko Mikhail Anatolievich , Rahimov Timur Rinatovich 
Published: September 2020

Abstract
The development of drilling technologies, the constant increase in the complexity of the geological conditions in the drilling areas, the need to involve hard-to-recover reserves in the development, and economic aspects have stimulated the development of horizontal drilling in the Russian Federation. Horizontal drilling volumes have increased several times over the past ten years. There are also changes in the design and completion of horizontal wells (multi-laterals for example), increasing the variety of geology of the target layers, the variability of the LWD. Therefore, taking into account the high volume of horizontal drilling in Rosneft, it is became necessary to systematize and classify wells by degree of complexity for geosteering in order to more effectively develop resources and improve the efficiency of geosteering of horizontal wells.
This article will describe an approach to calculating the new parameter "Geosteering Difficulty Index" (GDI), which characterizes a horizontal well, and classify wells by geosteering complexity. Examples of optimization of used resources and services based on the presented classification are given, which, as a result, reduce costs and increase the economic efficiency of drilling horizontal wells.
The drilling complexity index DDI (Drilling Difficulty Index) usually uses in international practice. The higher the DDI for a well, the more complex the design of the well, the more complex the technologies needed for drilling this well, the higher the qualification of personnel, etc. (Filimonov et al 2012). Similarly, we introduce a new industry indicator-the geosteering complexity index. It will take into account the geological features of the drilling area and may be used to rank wells by complexity for geosteering.
Gas Cap Injection as an Associated Gas Utilisation Method. Experience of Novoportovskoye Field
Authors: Janan Bogdan Sultan , Koryakin Fyodor Andreevich , Sherstoboev Evgenii Andreevich , Isakov Kirill Dmitrievich , Virt Vitaliy Igorevich , Kashapov Denis Zabirovich 
Published: September 2020

Abstract
This work describes the technological solutions that were used in the development of the Novoportovskoye field - a large oil and gas condensate field in the Yamalo-Nenets Autonomous Okrug. In particular, optimization of the associated gas utilization strategy is considered by organizing the reservoir pressure maintenance. The decisions were based on 3D mathematical calculations, analytical estimates, analysis of field information and reservoir simulation.
The paper presents the results of calculations performed to determine the specific efficiency of gas injection at productive formation. Additionally, weight coefficients of gas injection were calculated for gas well sites to identify the best injection zones. The paper provides the estimation of the current effect of the continuous two-year gas injection. The formation response to the gas injection into the gas cap was estimated by the usage of pressure-observation wells data, data from wells equipped with fiber-optic monitoring systems and by performing retrospective simulation.
The calculations made it possible to achieve complete utilization of associated petroleum gas and significantly increase the oil recovery factor.
Enhancement of Condensate Recovery of Fractured Well by Accumulated Condensate Vaporization at HPHT Reservoir Conditions
Authors: Solovev Daniil Yurievich , Eliseev Petr Ilich 
Published: September 2020

Abstract
On the example of a gas condensate reservoir of field in Western Siberia with HPHT conditions, high condensate content and low permeability, the problem of reducing well productivity during operation are considered. Restoring of the near wellbore area permeability methods, reduced due to the buildup of retrograde condensate are studied. The effectiveness of previously performed acid treatments and solvent injection has been considered in order to increase the productivity of such wells. The analysis of the ambiguity and variable success of such events is carried out.
An unconventional, but promising method of the condensate saturation reducing in the near wellbore areaof wells with multi-stage fracturing is proposed. These wells operate Achimov deposits with HPHT. This method consists of creating special thermobaric conditions in the near wellbore area, which allow to vaporize the largest part of the hydrocarbon condensate accumulated around the borehole. A condensate-saturated gas is extracted from the well to the surface. A search was held for simple, available and inexpensive technologies aimed at increasing both pressure and temperature in the wellbore and near-wellbore region.
Based on the results of calculations performed on digital wells models in OLGA software, the thermobaric conditions created at the bottom due to the thermobarochemical effects are determined. The measures effectiveness of the retrograde condensate evaporation in the near wellbore areaand restoration of well productivity have been evaluated.
Method for Solving Problems of Gas Production from Turonian Reservoirs
Authors: Bakulin Alexandrovich Denis , Zobov Mikhailovich Pavel , Cheremisin Nikolayevich Aleksey , Khlebnikov Nikolayevich Vadim 
Published: September 2020

Abstract
It is shown that hydrophilic (inhibitor) and hydrophobic (hydrophobizing) compositions are able to increase the permeability of the bottom-hole zone of the clay Turonian formation and prevent the formation (and, if necessary, destroy) gas hydrates in the bottom-hole zone of the formation. Hydrophilic and hydrophobic compositions contain solvents (methanol or petroleum ether) that are easily removed by the gas flow, and active non-volatile components (ABR or magnesium chloride) that remain in the formation. The use of "active substance + volatile solvent" compositions allows to have a long-term effect on the reservoir Bottom-hole formation zone (BHFZ) and easily remove liquids from the gas formation by gas flow.
The use of hydrophobic compositions and fluids is promising in the production of oil and gas from clay reservoirs (Cenomanian, Turon, Senon, Bazhenov and Tyumen formations, etc.).
Study of Polymer Flooding at Pore Scale by Digital Core Analysis for East-Messoyakhskoe Oil Field
Authors: Yakimchuk Ivan , Evseev Nikolay , Korobkov Dmitry , Ridzel Olga , Pletneva Vera , Yaryshev Mikhail , Ilyasov Ilnur , Glushchenko Nikolay , Orlov Alexander 
Published: September 2020

Abstract
This work demonstrates the results of polymer flooding simulation at pore-scale level using digital rock analysis by means of the density functional method for representative core samples from the PK1-3 formation of the East-Messoyakhskoe oil field. Obtained results made it possible to estimate the key factors impacting the polymer solution efficiency and to determine the relative permeability curves and displacement efficiency at pore level. This allows to conduct a sensitivity analysis and provides recommendations for further development of the field.
In the study, an increase in the displacement coefficient due to polymer flooding is observed in a wide range with a maximum of about 26% with respect to the baseline scenario of the water displacement. Furthermore, a decrease in the ratio of the viscosities of oil and displacement agent from 100/1 to approximately 3/1 led to a switch of the dominant physical mechanisms, from viscosity instability to velocity stripping.
Some Possibilities of Fluid Typization in Core Samples at Rig Site Applying Nuclear Magnetic Resonance
Authors: Belousova Natalia , Murzakaev Vladislav , Alexandrov Artem , Skirda Vladimir , Doroginitsky Michael 
Published: September 2020

Resume
In the framework of the contract with the Ministry of Education 2010-2012, TNG-Group andKazan Federal University developed a mobile YaMR-Kern unit to acquire information on filtration-capacitive properties of full-sized freshly drilled and extracted core samples, to estimate porosity, to determine free and bound fluids, permeability, residual water saturation, to assess the nature of saturation by analyzing the two-dimensional distribution of relaxation times and diffusion coefficient directly at the wellsite without preliminary core preparation for studies. Efficiency of the unit was tested on more than 1600 m of full-sized core samples taken from sediments of various ages and saturated with oils of various viscosity grades.
The core study directly at the wellsite, that is, immediately after its extraction to the surface, allows not to lose the very first information about the studied object as soon as possible, since the study of the core drying process showed that during the first hours the core loses up to a third of fluid-saturated porosity, and 20 days later dries out almost completely. Scanning the NMR properties of the core is carried out with high detail, every 1-2 cm, and does not involve any preparatory work, that is, the core does not break down and can later be used for laboratory studies of both full-sized core and standard samples. Such information is extremely important at the stage of exploratory drilling on poorly studied survey targets, as well as in the study of a thin-layered section of wells.
Quantitative Analysis of Whole Core Photos for Continental Oilfield of Western Siberia
Authors: Abashkin Vladimir Viktorovich , Seleznev Ilya Alexandrovich , Chertova Anastasia Alexandrovna , Istomin Sergey Borisovich , Romanov Dmitry Vladimirovich , Samokhvalov Andrey Fedorovich 
Published: September 2020

Abstract
The paper considers methods for automatic description of lithotypes as well as modeling of reservoir properties based on analysis of whole core photographs. The specific nature of the considered approach is the solution of applied problems based on relatively small training data sets using machine learning techniques. Also, one should highlight that the results of lithotype classification and reservoir properties modeling can be obtained in a form of high-resolution curves, which resolution is restricted by the quality of the core images. Additionally, during analysis of core photos several sets of curves are derived, which also could be used at different stages of analysis and interpretation of geological and geophysical data. Also, the considered approach could be useful for development of high-quality training data sets for neural network models.
Some Rules to Optimize Process of Planning Geomechanics Core Testing Program
Authors: Zinovyev Alexey Alexeevich , Korelskiy Evgeny Pavlovich , Chettykbayeva Kamilla Nusupbekovna , Petrakov Yuriy Anatolyevich , Sobolev Alexey Evgenyevich 
Published: September 2020

Abstract
In this paper, some features of conducting experiments on core samples to determine mechanical properties were established. Detailed description for such type of testing is poorly described in regulatory documents (Russian State Standard, ASTM).
Problem of specific test methods selection in accordance to task before the geomechanical modeling is considered. For the most issues, a series of experiments to build a failure envelope is required. Details of sample preparation for compression tests are regarded. In particular, the advantages and disadvantages of different methods for preserving in-situ core saturations are discussed: the collection of an isolated core with subsequent conservation or the preparatory work with the extraction, drying and saturation of samples.
While conducting multi-stage compression tests for building Mohr circles, chose of the right moment to stop the loading stage has a significant effect to prevent destruction of the sample in the early stages. This paper demonstrated that for specimens characterized by a shear failure type, it is recommended to focus on the plot "axial stress - volumetric strain". In particular, the inflection point of the curve, that is the moment of reaching the maximum value of volumetric deformation could be selected as a criterion for the loading stage termination.
For samples with high porosity, a complete testing cycle to build the Mohr circles and the entire failure curve is given.
Methods for Studying Two-Phase Flows in Porous Media: Numerical Simulation and Experiments on Microfluidics Chips
Authors: Khayrullin Marsel Mansurovich , Zakirov Timur Rustamovich , Grishin Pavel Andreevich , Shilov Evgeny Dmitrievich , Bukatin Anton 
Published: September 2020

Abstract
In this paper, experimental and computational approaches are used to study multiphase flows. In the first method, filtration experiments are carried out using microfluidics technology. Microfluidic chips were made from polydimethylsiloxane using soft lithography. To give the desired surface properties, the inner walls of the channels were treated with a hydrophobic or hydrophilic coating. Injection of liquids was carried out using a syringe pump at a constant flow rate. To measure the pressure difference at the inlet and outlet of the microchip, we used the method of measuring changes in gas volume. For numerical modeling, the most modern model of the Boltzmann lattice equations, adapted for two-phase flows of incompressible immiscible liquids, is used. The effects that occur at the phase boundary are described using the color field gradient model. Experimental studies have shown the possibility of studying the processes of liquid displacement from the microchannel system in a microfluidic chip simulating a porous medium. The dynamics of the displacement of liquids (water and oil) from a system of microchannels with different hydrodynamic drag cardinally depends on the angle of wettability of its walls. In the case of microchannels with hydrophilic walls, a complete displacement of oil by water occurs almost simultaneously from both channels. When water is displaced by oil from channels with a hydrophilic and hydrophobic coating, it is required to create an increased flow rate of the displacing liquid through microchannels. In this case, at the junction of the microchannels, before leaving the chip, emulsion droplets of "water in oil" will form. In the case of oil displacement by water from microchannels with a hydrophobic coating, complete removal of oil from the channel with high resistance did not occur. This is due to the fact that the viscosity of the oil is 30 times higher than the viscosity of water. The paper shows a successful comparison of the results of numerical modeling and experimental research in a two-phase flow in a pore doublet. Demonstrated examples of the developed program code are shown: the formation of emulsions at high flow rates, the motion of a drop under the influence of mass force; flow in digital microtomographic image; displacement of viscous oil from the pore medium.