bluuebunny/crossref_metadata_2025_split huggingface dataset:
Patterns of Hydraulically Conductive Fractures' Positions and Spatial Orientations Near Large Faults
Authors: Dubinya Nikita 
Published: October 2019

Abstract
In the study the main tendencies in fracture development in rock masses are investigated. The question of natural shear fractures' fluid conductivity is particularly analyzed as this question is important for development of hydrocarbon fields. The localization of the majority of hydraulically conductive fractures in the reservoir and their preferable spatial orientations are analyzed based on the hypothesis of an existing relationship between current stress state of the rock mass and the fractures' hydraulic conductivity. A mathematical algorithm for solving the forward problem of finding all possible spatial orientations of hydraulically conductive fractures for an arbitrary stress tensor is proposed. Stereonets are used as a tool for interpreting the spatial orientations of fractures. The proposed algorithm is used to find the main tendencies in hydraulically conductive fractures' spatial orientations for the following cases: gradual increase of the considered object's depth; gradual change of one of the principal stresses; case of approaching a large fault. A relationship between typical behavior of the fractures and stress regime in the region is found out alongside with typical changes in spatial orientations of hydraulically conductive fractures while approaching faults of different types. The obtained results may be directly used for planning the development of oil fields, characterized by a considerable contribution of fractures to permeability. The results are particularly important for development of fractured zones in vicinities of large faults. Moreover, the proposed algorithm of finding the geometrical properties of hydraulically conductive fractures may be applied based on results of three- and four-dimensional geomechanical modeling carried out for particular fields providing an opportunity to both determine the zones being perspective for development, and predict the changes of these zones' properties during reservoir development.
An Integrated Approach for Planning of Multistage Hydraulic Fracturing in Low-Permeability Gas-Saturated Reservoirs with Natural Fractures
Authors: Pavlyukov Nikolay , Melikov Ruslan , Pavlov Valeriy , Ptashniy Aleksandr , Stepanov Anatoliy , Kalabin Artemiy , Kuzovkov Anton , Gordeev Aleksandr , Arzhilovskiy Andrey , Samoilov Mikhail , Matveev Dmitriy , Prokhorov Alexey , Khamidov Timur , Korolev Aleksandr , Loznyuk Oleg , Shaybakov Ravil , Gabuniya Georgiy 
Published: October 2019

Annotation
The peculiarity of this work is in the planning of the pilot works and the development of low-permeability fractured gas reservoir by horizontal wells with multi-stage fracturing considering natural fractures impact which taken into account on the basis of integrated approach with petrophysical, geological, geomechanical and dynamic modelling.
The article presents the results of multivariant calculations of hydraulic fracturing design dynamic modelling with and without natural fractures depending on the well placement, length and orientation of the horizontal well, geometry of hydraulic fracture, as well as possible effects that occur during the operation of the wells.
Technological constraints (geomechanics input) were taken into account as a basis for evaluation of horizontal well trajectories with multi-stage fracturing for the pilot works and recommended for implementation during the subsequent fullfield development for target gas reservoir, as well as replication of the experience for the similar assets of the Company.
Modified Nonlinear Mohr Criteria of Multilayer Rocks
Authors: Aliev Mekhrali , Lutfullin Azat , Shafieva Svetlana , Gilyazova Svetlana 
Published: October 2019

Abstract
A modified strength and destruction criterion in the form of the Mohr nonlinear dependence for multilayer rocks has been developed in this work. The criterion for rocks with evident anisotropy is a passport of strength, as it is adopted in the form of the envelope equation for Mohr's limit circles. To determine the strength characteristics, it is proposed to use the results of uniaxial compression and breaking off tests in different directions to the foliation. To obtain acceptable results, it is sufficient to determine the strength of a multilayer rock without applying lateral pressure along and across the foliation and at an angle of 45° to the main anisotropy directions aligning with the layers. The following aspects are reviewed: the possibilities of the developed criterion application for solving the stability problems of wells drilled in the multilayer rocks, as well as in solving geomechanical issues to determine the ultimate stresses under the action of a spherical tensor of quite high intensity.
Integrated Modeling of the Complex Multilayer Oil, Gas and Condensate Field Development as a Method of the Project Value Increasing
Authors: Bogdanov Evgenii , Chameev Igor , Nekhaev Sergey , Badgutdinov Ruslan , Tkachuk Anton , Shorokhov Aleksei 
Published: October 2019

Abstract
The work is devoted to highlighting the experience of creating a full-scale integrated (reservoir – well – infrastructure network) model of gas reservoirs of the large oil, gas and condensate field of Yamal, finding optimal solutions to the problem of both development oil rims, gas caps of productive reservoirs and dry gas reservoirs, as well as the gas injection system on the efficiency of the field development process as a whole. The task included creating, history matching and integration of the hydrodynamic models with surface facility system, the elimination of "bottlenecks" in the gas facility network system and the determination of the optimal solution to the problem of hydrocarbon production (oil production from oil rims and gas production from gas caps and dry gas formations).
Conducted integrated calculations allowed us to consistently identify the risks of the project and allowed them to be minimized at the preparatory stage of the project, which leads to an increase in the value of the project.
Automated Identification of the Optimal Sidetrack Location by Multivariant Analysis and Numerical Modeling. A Real Case Study on a Gas Field
Authors: Magizov Bulat , Topalova Tatyana , Loznyuk Oleg , Simon Evgeniy , Orlov Alexandr , Krupeev Vsevolod , Shakhov Dmitry 
Published: October 2019

Abstract
The task of choosing the sidetrack trajectory for drilling is one of the most common among specialists while workovers planning in oil and especially in gas fields. This task is solved by reservoir engineers, geologists and drilling engineers, both in a team and separately. Despite the widespread use of software for processing and analyzing the data and high automation of most routine tasks, many oil and gas companies lack a unified methodology for choosing sidetrack trajectory. Each oil and gas company has its own approach to this task. Usually, the process of analyzing candidates is based on the expert opinion of the well design engineer and has several limitations, such as: ▪Short deadlines - on average, it takes from two to three weeks to select the sidetrack drilling trajectory.▪Low automation of the process of creating and analyzing the trajectory - the trajectory is created by a specialist manually, this process takes, considering the time for analysis, from two to four days for one trajectory. As a result, about five candidates are considered for the allotted time.▪Analysis of a small number of influencing factors — two-dimensional maps of averaged permeability, residual reserves maps, a seismic map of average amplitudes, as well as the proximity of the candidate to the existing well stock are mainly considered during analysis of the trajectory.▪Prediction of the flow rates is not always based on the hydrodynamic model - when calculating the candidate's starting flow rate due to tight deadlines, not all trajectories are analyzed using the hydrodynamic model, for part of the trajectories flow rates are calculated only using analytical techniques, such as the Joshi equation (Joshi, 2018).▪The risk of human factor.
Sidetrack drilling, like other workovers, is aimed at increasing the flow rate of the well and the cumulative production of the entire field. In gas fields with falling production and high drilling density, sidetrack drilling can help significantly extend production time with the same level or increase production. Drilling a sidetrack, rather than a new well, can significantly reduce drilling costs, since the main well has already been drilled. Potentially, almost any well, especially with falling production rate or high water cut, can be a candidate for sidetrack drilling. According to the data from the Federal Supervision of Natural Resources in 2017, almost a quarter of all wells in Russia are inactive or shut, which is almost 60,000 wells.
Technologies for the Study of Full-Size Core with CT and Numerical Simulation Methods
Authors: Korost Dmitry , Belokhin Vasily , Kudaev Artur , Khomyak Alexey , Asryan Samvel 
Published: October 2019

Abstract
The work studies "digital petrophysical" technologies applied to the full-size borehole core. During the study various CT aspects were compared: the use of different CT systems, their key characteristics and principles of technological solutions, depending on the general technical conditions and possible tasks.
Special attention is paid to the modeling of real characteristics of sections according to CT data. The paper describes calibration procedures and subsequent calculations based on two-energy survey. The results obtained (volume density data stacks and Zeff) have high convergence with GIS data, profile and laboratory measurements.
Brand new results obtained on the basis of CT study of full-size core material are applicable both in the current petrophysical graphs of stone material processing and GIS interpretation settings. They also serve as a basis for the creation of digital models using the "digital core" technology.
Thick-Walled Cylinder Core Tests with Flushing by Various Fluids: Results and Practical Applications
Authors: Nepop Roman , Smirnov Nikolay , Molodtsov Roman , Khomenok Ivan , Abalian Artur , Atanes Andrea Martin , Maltsev Andrey , Nemirovich Gennady 
Published: October 2019

Abstract
This paper presents the results of studying petrophysical and geomechanical properties of rocks by conducting thick-walled cylinder core tests (TWCT) - triaxial compression with flushing by various fluids. Experiments were carried out for a limited number of core samples from the Ourinskoe Field, which is a part of the Western Siberia oil and gas-bearing basin.
In the framework of the study, various core testing schemes were applied, the results of experiments using different fluids for flushing were analyzed, and the optimal testing parameters (including loading rate, washing time, sample relaxation time, etc.) were selected. The result of the research is a detailed analysis of rock fragments removed by different fluids as a result of triaxial compression and subsequent destruction of a thick-walled cylinder. The paper presents the qualitative relations of the particle size distribution on the prevailing deformation patterns (elastic or plastic), analyzes some petrophysical properties of the strata that control the behavior of the system "rocks – fluid", and consider typical scenarios for TWCT experiments.
The obtained experimental data served as an important source of additional information for assessing the draw-down pressure that controlled sand inflow into the wellbore, to determine its particle size distribution, as well as to calculate the size of the wire-wrapped filter liner completion for sand preventing.
A New Mixed Wettability Evaluation Method for Longmaxi Formation Shale in the South of the Sichuan Basin, China
Authors: Tao Liang , Guo Jianchun , Zhou Xiaofeng , Gayubov Abdumalik , Kitaeva Alena , Chen Chi 
Published: October 2019

Abstract
Shale rocks are multi-component materials with complex interactions among different components. As a result, shale wettability evaluation becomes extremely difficult and knowing key factors that control shale wettability is particularly important for shale reservoir development. In this paper, wettability of both shale surface and pore of Longmaxi Formation in the southern Sichuan Basin were comprehensively evaluated by low field nuclear magnetic resonance (NMR) together with experiment; a new concept, mixed wettability index, was introduced to quantitatively evaluate the mixed wettability and clarify the key factors affecting shale wettability. The test results of wettability of different shale samples by the new method show that the surface of the Longmaxi Formation shale exhibits complex non-uniform mixed wettability, both oil-wet and water-wet, while the shale surface tends to be more oil-wet, the contact angles range from 15.9 ° to 63.7 °, with an average of 41.3 °, when tested with distilled water, and the shale is more water-wet under formation temperature. The shale pore also exhibit complex mixed wettability. The clay mineral content is the dominant factor affecting water wettability of shale, but when reaching beyond a certain value, it inhibits shale water wettability to some extent. The organic carbon (TOC) is the dominant affecting factor of oil wettability and positively correlated with oil wettability of shale. The research results are helpful for making clear the micro mechanism of the action between fracturing fluid and shale reservoirs and designing fracturing scheme.
Ways to Justify 4D Seismic Exploration
Authors: Vasilev Mikhail , Butorin Aleksandr 
Published: October 2019

Abstract
The paper describes an approach to justifying the need for 4D seismic exploration. Starting from the analysis of all the information available on a reservoir geological structure and the quality of seismic data, a wave field model is then built based on the existing geological model of a real field. Models with various reservoir fluid types are tested.
In the end, conclusions are made about the possibility to observe the effect of reservoir development in the wave field during repeated seismic surveys and the efficiency of this approach based on a case study of one of the Gazprom Neft fields.
Phase Decomposition for Interpretation of Thin Layers – Possibilities and Limitations
Authors: Popov Mikhail 
Published: October 2019

Abstract
The relatively new method of phase decomposition (Castagna et al. 2016) is complex to understand and use, but has good potential for the analysis of lateral changes in thin layers. To develop a better understanding of this technology, a set of synthetic models of wedges and the subsequent phase gathers for these models was calculated and analyzed.
The results obtained from this analysis demonstrate that changes in the phase depend on the layer thickness and the proportion between the reflection coefficient of the top and the bottom of the layer. We can see that the phase split and shifted from the original in tuning zones. For wedges with Reflection Coefficient (RC) in different polarity for top and bottom, phase gathers were more differentiated than for wedges with RC in the same polarity for top and bottom. For analyzing phase difference, we use prestack offset visualization technology (Fink 2010), which helps visualize changes in phase in the tuning zone by horizon. For analyzing lateral changes in the tuning zone, we must select zones with equal thickness of thin layers, because thickness also influences phase changes and will mask lateral property changes. The proposed method of using phase decomposition will help to analyze the property changes of the thin layer below traditional seismic resolution.
A Research of High-Quality Sandstone Reservoirs in Deep Formation in the Central Depression of the Fergana Basin, Central Asia
Authors: Lin Yaping , Wu Tiezhuang , Kong Linghong , Zheng Junzhang , Song Lianteng , Tan Liyong , Guo Chaosheng 
Published: October 2019

Abstract
In this study, the outcrops, core-data, well-logging, and rock thin-film were used. Based on the core lithfacies, single-well and multi-wells sedimentary facies, and the structure texture, the Mesozoic and Cenozoic reservoirs were studied in the central depression zone of the Fergana Basin.
In this paper, the petrological characteristics, pore structure and diagenesis characteristics of the reservoirs were systematically studied on the base of thin-film (slice), scanning electron microscopy, X-ray diffraction of clay minerals, physical property analysis and constant velocity mercury intrusion. The reservoir differentiation in this area was analyzed. The genesis and the formation conditions of relatively high-permeability high-quality reservoirs were surveyed, it is believed that high-quality sandstone reservoirs are mainly developed in relatively high-structured sandstones, and the reservoirs are strongly squeezed or stretched to increase the original porosity. The presence of ultra-high pressure (pressure coefficient &gt; 2.0) allows the original relative high porosity to be well preserved.
The high energy and thick-layer river sand bodies in the delta front are the basis for the formation of relatively high-porosity and high-permeability reservoirs in this study area. The high-pressure and ring-side cementation formed by rapid deposition facilitates the preservation of intergranular pores and is the native of relatively high-porosity and high-permeability reservoirs. The key to pore preservation, in addition, the dissolution contributes to the formation of relatively high porosity and high permeability reservoir pores. The study suggests that the high-quality sandstone reservoirs in the central depression of Fergana are formed by the following factors: high-yield reservoirs are mainly controlled by sedimentary features, structural features, channel sandstones, pore structures, ultra-high pressure, and lithologic characteristics. According to these control factors, the author divides the reservoirs in this study area into three categories: Class I—high-porosity and high-permeability reservoirs with porosity above 17% and permeability of 87-2417md; Class II—medium-hole high-permeability reservoirs, porosity is 8-17%, permeability is 1.2-116md; Class III—low porosity and low permeability reservoir, porosity is less than 8%, permeability is less than 1.2md; the main reservoir of the study area is clearly defined The characteristics of the main strata, the characteristics of the high-quality sandstone reservoirs, and the distribution facies.
This study is a kind of exploration of reservoir porosiry of the central depression in the Fergana Basin, it analyzes the relevant laws and characteristics of reservoirs in the deep formation of this area, and provides suggestions for the research and development of the region.
Modern Seismic Technologies for Localization of Zones with Improved Reservoir Properties of Palaeozoic Deposits in Western Siberia
Authors: Volkova Aleksandra , Merkulov Vitaly 
Published: October 2019

Abstract
The aim of the work was to develop a methodological approach to the localization of promising areas of improved reservoir properties at one of the fields confined to the pre-Jurassic Palaeozoic deposits.
The paper discusses the integration of seismic attribute analysis and other geological and geophysical materials, the most significant for this object of research of which are reservoir electric microimagers and photo-scanning core, oriented by paleomagnetic methods. In addition to the localization of prospective zones, the fracture density was estimated, and the preferred fracture directions were also identified.
Approach to the Assessment and Control of Risk to the Health of Oil Company Employees On the Basis of Information Obtained From Portable Staff Devices
Authors: Tikhomirov Leonid , Tachkin Dmitry , Sinaisky Sergei 
Published: October 2019

Abstract
It is proposed that decision-making issues in the HSE management system should be resolved taking into account factors that are new, such as employees' health and their level of stress, thereby significantly improving the quality of the decisions made by management.
A new approach to assessing and monitoring occupational health risks for employees has been developed using information obtained from wearable personal devices (WPD's) so that employees' medical health characteristics can be used in the HSE management system.
Technology involving the remote, continuous monitoring of employees' health using WPD's enables information to be acquired in a mode close to real-time mode.
Incorporating supplementary, up-to-date information concerning employees' health, and level of stress, into the process of preparing and making decisions has a more significant impact when compared to traditional approaches based on a system of scheduled medical check-ups.
Advanced LWD Technology Application at the Caspian Offshore Oilfields
Authors: Golenkin Mikhail , Rakitin Mikhail , Shtepin Daniil , Mityagin Artem , Urmantseva Lena , Golubtsov Ruslan , Kuzakov Vittaly , Shaymardanov Niyaz , Cheprasov Alexey 
Published: October 2019

Abstract
Offshore oilfields are characterized by complex geological structure, such as presence of fault blocks, significant lateral changes of the rock properties. These features require accurate technology selection used during horizontal production wells drilling. Offshore drilling is fundamentally different from that on land, that requires a special selection of logging-while-drilling (LWD) technologies. The number of exploration wells is limited, therefore LWD tools and data interpretation should solve the problem of additional field exploration, that is impossible without advanced LWD technology application. Currently, LWD allows perform measurements similar to wireline logging – nuclear magnetic resonance logging (NMR), formation testing and obtain azimuthal density data. In addition, it is possible to perform measurements using reservoir-mapping-while-drilling service to solve geosteering tasks.
This paper discusses examples of optimal well placement within the target zone, considering integrated interpretation of advanced LWD data for reservoir properties estimation, reservoir pressure behavior understanding, and choosing completion strategy. According to reservoir-mapping-while-drilling service data interpretation, density azimuthal data the geological model was updated. To clarify the petrophysical properties LWD-NMR data were used. These data allow to obtain porosity estimation, permeability, residual water saturation coefficient, evaluate bottomhole formation zone damage. Formation testing data were used to estimate reservoir pressure and hydrodynamic parameters of the target zone. Integrated interpretation of LWD data has been used to select the most optimal design of lower completion scheme and to control the development of reservoir.