bluuebunny/crossref_metadata_2025 huggingface dataset:
Virtual Flowmetering for Intelligent Wells
Authors: Danilko Aleksej , Senkov Alexandr , Andreev Alexey
Published: October 2019

Intelligent wells are equipped with tools for production control; however, they often do not answer the question of production zones allocation. Effective monitoring is only possible with an understanding of the inflow profile along the well; but, physical flowmeters are not cheap and are not always profitable. This work considers the use of virtual flowmeters for the purpose of understanding the profile of fluid flow to the well.

An intelligent horizontal well with five production zones was considered. Each zone was equipped with pressure sensors and a flowmeter. On the surface, there is data of wellhead pressure and multiphase flow rates.

As part of this work, a model of fluid flow in the bottomhole zone, annular space, inflow control valves, and tubing were designed. The model was calibrated with real-time measured data: pressure in the annulus, liquid flow of each zone, as well as wellhead pressure and surface flow rates.

In cases where there is no physical flowmeter, but there are sensors in the tubing and annular space, this approach can be used to calculate the production from each zone. Such a tool, when connecting the model to a real-time data system, allows use of the available information as efficiently as possible to automate the process of monitoring and manage production as well as provide opportunities for proactive production monitoring systems.

In addition to virtual flowmetering, the method can be used to clarify reservoir parameters, such as reservoir pressure, permeability, and skin factor.
Field-Scale Automatic Facies Classification Using Machine Learning Algorithms
Authors: Kuvichko Alexander , Spesivtsev Pavel , Zyuzin Vladimir , Istomin Sergey , Kalistratov Alexey , Kuznetsov Maxim , Igitov Semen
Published: October 2019

We propose a novel approach to facies classification based on a supervised machine learning algorithm. This approach allows for the automatic facies classification on a field scale based on an ensemble of Decision Trees algorithm associated with gradient boosting. Major steps of the workflow include data integrity assessment, data scaling, identification and correction of gaps in data, log processing, feature engineering, training, testing, and tuning the hyperparameters on the validated set of data. At the ultimate stage of the workflow, the algorithm accepts a set of well logs as an input and produces a discrete facies type as an output. This method substantially increases the quality of the facies classification, that is key to further geological modelling and dynamic simulation that help reduce drastically the risk of incorrect well planning, fracturing and other operations, thus avoiding a huge negative financial impact. The novelty of approach is related to the selection of machine learning algorithms that are best fitting the dataset, combined with a workflow to enhance the dataset itself.
Reduced Order Reservoir Simulation with Neural-Network Based Hybrid Model
Authors: Temirchev Pavel , Gubanova Anna , Kostoev Ruslan , Gryzlov Anton , Voloskov Dmitry , Koroteev Dmitry , Simonov Maxim , Akhmetov Alexey , Margarit Andrey , Ershov Alexander
Published: October 2019

This paper considers the development of a computationally fast model for simulation of multiphase flow in porous media for a heterogeneous reservoir with the unlimited number of wells characterized by a different type of completion. This fast solution has been obtained by means of replacing the differential equation governing the flow in porous media by approximate governing equations which are parametrized by convolutional neural networks. The matching of the dynamic properties of the original and reduced models is ensured by conservation of spatial invariance property of the equations. The suggested approach is characterized by the minimal number of limitations and shortcomings related to geological-hydrodynamical structure and size of the original model. Also, there is no necessity of additional model training for reservoirs not included in a training dataset. Suggested approach has been evaluated on the synthetic benchmark test model SPE10, where a significant decrease in computational time has been demonstrated comparing to a traditional commercial reservoir simulator. Based on the results of all demonstrated test case scenarios, it could be noted that hybrid hydrodynamic modeling leads to a significant reduction in computational cost (by a factor of few hundreds), maintaining at the same time required accuracy of calculations.
Integrated Asset Modelling and Automated Workflows from Pre-Production to Full Field Development Stage for a Giant Green Field West Qurna-2
Authors: Kunakbayeva Liliya , Gauder Denis
Published: October 2019

The West Qurna-2 field is one of the biggest undeveloped oil fields in Iraq. The development of the field is handled by the Iraqi Basra Oil Company and a consortium between LUKOIL and the National Iraqi North Oil Company. The production of the field started in 2014. This paper describes how the integrated asset model (IAM) and automated workflows have been used to support the field's development from first oil to full field development.

Along the field's development stages, the IAM system has assisted LUKOIL in its operations.

Its availability for first oil allowed refining the assumptions made about the productivity of the wells and reservoir characteristics for issuing realistic production profiles, hence playing a crucial role in achieving the production's targets.

Subsequently, the wells have been gradually converted to artificial lift (electrical submersible pumps) and the IAM system has allowed for extension of the natural flowing mode of the wells, optimization of workover operations, short term optimization of the ESP operations and extension of their lifetime.

Today, the IAM system allows for mitigating the water handling constraints through tailor-made field-wide optimization algorithms. The latter optimizes not only the field operations through integrated asset planning but also the water production and injection system continuously.

Overall, the IAM system has proven to be instrumental for the development and optimisation of West Qurna II. It has allowed to de-risk the initial production, optimize the workovers in the field, enhance the ESP performance and lifetime, optimize the pressure maintenance systems, etc. It has also provided a platform to empower multi-disciplinary teams.

The saving figures presented in this paper alone amount to around 7 million dollars in 2015-2016 and it is not unreasonable to ultimately expect total savings of tens of million dollars. Such savings make the implementation of IAM systems very attractive for similar green field operations.

LUKOIL has made critical choices for ensuring the success of the initiative, such as allowing for customization and flexibility of its IAM system, putting the necessary efforts in developing and maintaining accurate hydraulic models and starting simple and keeping focusing on the continuous and organic development and improvement of its IAM system.

This paper demonstrates how IAM systems can be practically used for optimization activities in a green field, and the associated direct benefits. It also details how to maintain such systems continuously up to date for a field in development phase, where the layout is continuously changing. A series of best practices are identified for ensuring successful embedment of these advanced approaches within the day-to-day operations.
Applying Machine Learning Methods to Search for Missing Net Pay Zones in Mature Oilfields Wells
Authors: Egorov Dmitry Vitalievich , Sabirov Arthur Rustamovich , Osmonalieva Oksana Taalaevna , Belozerov Boris Vladimirovich , Reshytko Alexander Alexandrovich , Klenitskiy Anton Nikolaevich , Shchepetnov Arseniy Andreevich , Semenikhin Artyom Sergeevich
Published: October 2019

The main aim of this work is to develop new approaches for processes of searching previously missed potential net pay intervals within wells from well log data of brownfields with machine learning algorithms. The practical interest for such a solution is an extraction of additional oil potential recovery from field data in order to prolongate development and production life of mature fields through development of system capable to automatically make recommendations on previously misinterpreted intervals.

Besides application of cognitive technologies the developed methodology includes also a workflow of cross-functional interaction of experts from different disciplines (geologist, petrophysicists) between each other and digital system. The system is based on modern deep learning architectures including convolutional and recurrent artificial neural networks. It utilizes well log data and corresponding interpretation of many specialists in order to accumulate or digitize a vast amount of previous experience. It can be used for the following robust re-interpretation of data in those parts of wells which were not previously considered in terms of net pay intervals but have high potential for new oil saturated thicknesses according to geological conditions and previous experience of manual investigation of such intervals.

The field test on a basis of described methodology was conducted on assets of Gazpromneft PJSC in Yamanlo-Nenets Autonomous Region, Western Siberia. The comprehensive volume of geological and geophysical information from oilfield was collected including well log data and corresponding results of expert interpretation. This information is used for model training and then predictions about previously uninterpreted intervals are made, providing business user a new interpretation of target geological objects. New interpretation produced by model was compared with current manual interpretation and new net pay intervals were considered as previously missed and potentially oil saturated. At the next step those intervals were examined by petrophysicists, geologists and reservoir engineers in order to estimate probability of oil saturation. Intervals with highest expert marks were proposed for field work and tested by perforation of the target zone. As a result of described process new net pay intervals were found and well, which was suspended, started a new production life. Obtained results confirm high potential of machine learning models application for search of new potential net pay intervals by helping an expert in daily geological and petrophysical tasks.
Analysis of Flow Characteristics in Porous Media with Heterogeneity at Microscale and Macroscale
Authors: Gerke Kirill M. , Isaeva Anna V. , Karsanina Marina V. , Shaporenko Elena V. , Korost Dmitry V.
Published: October 2019

Hydrodynamic or oilfield scale models are needed to predict long-term the production process, to design and optimise well placement and evaluate the outcomes of different enhanced recovery practises. These models operate using continuum medium approximations and upscaled effective porous media properties such as permeability, relative permeability and capillary curves and are conventionally based on (multiphase generalization of) Darcy and continuity equations. In this work we explored the difference between flow patterns on the Darcy scale depending on how we parameterized the model – using scalar permeability values, or based on pore-scale simulations on 3D pore geometries of real rock samples. In the latter case two permeabilities were utilized – conventional directional permeability (in three directions) and full permeability tensor. Our results strongly support the idea that full tensors are needed to accurately represent fluxes at Darcy scale then upscaling from core-scale measurements or simulations, or even if using geologic/geostatistical model (with spatial heterogeneous distribution of flow properties). More specifically, our upscaled Darcy scale model parameterized using hypothetical scalar or pore-scale simulated permeabilities revealed: even a simple scalar permeability field, if heterogeneous, produces significant off-diagonal terms in tensorial permeability results; using tensoral permeabilities when upscaling from the core-scale results in significant difference in upscaled (tensorial) permeabilities compared to conventional directional simulation framework.
Mathematical Model for Describing the Growth of Mini-Fractures in a Fractured Medium
Authors: Bykov Aleksander , Bychkov Alexey , Nevmerzhitskiy Yan , Zavialov Ivan , Zavialova Natalia , Elmira Salimgareevs , Yemchenko Olga
Published: October 2019

The main feature of fractured porous reservoirs, such as carbonates, is the presence of cracks of all scales, from the micro level to the main cracks that can cross the whole field. In connection with this feature, and beacause of the influence of formation perturbations on the geometric parameters of cracks, the interpretation of minifrac is a difficult task, since leak-off depends in a complex way on pressure. In this regard, the actual task of building a mathematical and numerical model that could be able to take into account the many processes that affect the anomalous dynamics of the bottomhole pressure.

As a resul, a physico-mathematical model, which describes the opening of pre-specified cracks in the three-dimensional case, as well as the generation of new cracks on the basis of the fracture criterion was constructed. Filtration in the matrix and the cracks on a small scale was considered in in obedience to the double porosity model – double permeability. The features of multiphase filtration of a power-law fluid were taken into account. The calculation of geomechanical equilibrium was carried out according to the model associated with the method of calculating frames and trusses.
Reservoir Flow Connectivity Estimation in Geomodels and New Capabilities of Geomodels using this Parameter
Authors: Popov Victor , Podnebesnykh Alexander , Pylnik Sergey
Published: October 2019

The main aim of the work is to find method to estimation flow connectivity without model simulator. The relations between flow connectivity and various reservoir geometry parameters were studied. Average number of reservoir intervals, intermittence, and reservoir boundary density parameter are not directly related with flow connectivity. Cluster proportion and net to gross ratio can be used with limitations for flow connectivity estimation when stochastic heterogeneity is low. The best estimation can be done by using neighbor reservoir parameter which correlation coefficient with flow connectivity is 0.99 and regression parameters are independent of reservoir modelling method and its options (variogramm range, nugget, net to gross ratio, object shape etc.). New method of flow connectivity coefficient estimation allows making local connectivity estimation and maps this parameter in order to evaluate potential flow rates of different regions of reservoir. Also flow connectivity should be used to rank realizations of lithology or net to gross properties in geological models in uncertainty analysis as a parameter which reflects production properties of reservoir.
Application of CRM-Like Models for Express Forecasting and Optimizing Field Development
Authors: Olenchikov Dmitry , Posvyanskii Dmitry
Published: October 2019

Lately, demand has increased for simplified field models (compared to 3D hydrodynamics) allowing to calculate a lot of production variants. One of promising approaches is CRM (capacity resistive model). Currently, several model classes are offered. The work is designed to improve CRM method for operative forecast of production indicators in active aquifer and in case of significant change of operation modes in wells. We have shown that the influence coefficients (of wells) are settable parameters of classic CRM, sensitive to changing the operation modes in wells. It limits CRM efficiency for tasks where well operation modes can change significantly, for instance, in waterflooding optimizing (WFO). The work offers the following CRM method improvements: using productivity coefficients instead of well influence coefficients;methods of direct reporting in equations of CRM-like model: influence of aquifer and crossflows between separate draining volumes.

The offered improvements will allow increasing the forecast performance of the model using productivity coefficients and direct reporting of aquifer and crossflows.

We have provided examples comparing CRM forecasts with the results of calculation of synthetic reference flow models. We have provided an example of application of the offered approach to waterflooding optimizing of a real oil field.
Evaluation of the Saturating Fluid Effect on the Composite Materials Elastic-Strength Properties
Authors: Pavlov Valeriy , Pavlyukov Nikolay , Krasnikov Artem , Lushev Mikhail , Eltsov Timofey
Published: October 2019

Effective assessment of the stress-strain state of the near wellbore zone is one of the key problems in the process of modeling the stability of the wellbore walls. Drilling mud infiltrates permeable rocks during the drilling process. This causes a change in the elastic-strength properties of rocks and, accordingly, the redistribution of tension around the well. At present, there are no computational methods that take into account the effect of saturation fluids on the change in the elastic-strength properties. A unified system approach for the implementation of this type of research when changing infiltration fluids is not developed yet.

In this paper, we study the effect of various types of drilling mud on the elastic-strength properties of core samples, which are equivalents of rocks (composite samples made of different sand and clay cement facies). Measurements of porosity, acoustic properties, ultimate strength for uniaxial compression, and static Young's modulus at different samples saturation are made. Studies of the elastic-strength properties of the samples are performed after 48 and 168 hours soaked in the drilling fluids. According to the study, the relative change in the dynamic Young's modulus with various sample saturation is 13.4-27.7%, the static young modulus (compression) is 19-40%, the dynamic Poisson ratio is 1.4-14.6% and the uniaxial compression strength is 28-35%. The data obtained indicate a significant effect of the saturating fluid on the elastic and strength properties of materials.

A numerical one-dimensional simulation of the stability of the borehole walls is performed, taking into account the type of saturating fluid and the relative change in the elastic-strength properties. The results indicate a change in the stability of the wellbore walls; the indicators of the change in the equivalents of the collapse gradient and hydraulic fracturing are 0.2-0.3 g / cm3. A change in Young's modulus of 30% affects the design parameters of a hydraulic fracturing fracture – by width up to 100%, by half length up to 50%.
Consideration of Elastic Properties and Stresses Anisotropy in Fracturing Planning
Authors: Krasnikov Artem , Melikov Ruslan , Pavlov Valeriy , Pavlyukov Nikolay , Subbotin Mikhail
Published: October 2019

Development of complex-build oil and gas reservoirs is associated with advanced technologies such as horizontal wells drilling and multi-stage hydraulic fracturing. Geomechanical modeling for hydraulic fracturing purposes is a fundamental tool for assessing technological constraints and risks, as well as increasing efficiency of reservoir treatment.

In proposed approach of horizontal stresses modeling and calibration to the actual hydraulic fracturing data additional features considered to compensate low contrast of Poisson's ratio calculated from broadband acoustics: elastic properties TIV-anisotropy, variation of Biot coefficient adjusted to mechanical facies, correlations between static elastic properties and petrophysical parameters based on core measurements.

Lab measurements on oriented core samples revealed elastic properties anisotropy that caused difference of the static young's modulus parallel and perpendicular to the formation bedding up to 80 – 100%, and for the Poisson's ratio is up to 10 – 20%. Considering these results stress calculation leads to a difference between an isotropic and anisotropic profile up to 20%, this has significant impact on the hydraulic fracture geometry.

The rock behavior under load is different and is determined by the properties of the rock grains and the contact between them. Thus, the section separation into mechanical facies plays an important role when estimating elastic parameters, including Biot coefficient (α), which is different for shales, sand and/or carbonate, for example. Correct estimation of α with respect to mechanical facies allows achieving good agreement between stress calculation and actual measurements obtained with a mini-frac job, thereby increasing fracture geometry prediction accuracy.

Another tool to compensate lack of stress contrast calculated based on standard 1D geomechanical workflow is the use of petrophysical parameters such as porosity, clay content, neutron density and its correlation with static elastic properties to estimate minimum horizontal stress. This method may improve geomechanical model matching with field observations, but it has a limited scope of application.

In this paper demonstrated that additional study of the rock properties with special logging and core measurements at initial phase of field development planning may significantly reduce geomechanical modeling uncertainties and improve understanding of hydraulic fracturing and fracture geometry, which is a basis for hydrocarbon production and economic evaluation of the project or the whole asset.

The paper presents adapted geomechanical modeling workflow based on special lab core testing and elastic properties anisotropy and Biot coefficient evaluation to adjust the horizontal stresses profiles in complex-build reservoirs to the field measurements and observations as well as to fracturing data in existing wells.
Patterns of Hydraulically Conductive Fractures' Positions and Spatial Orientations Near Large Faults
Authors: Dubinya Nikita
Published: October 2019

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

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

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

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

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

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

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

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

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

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 > 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

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

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

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.
Creation of New Multistage Frac Technologies for Implementation in Horizontal Wells in Oil Fields of the Republic of Tatarstan
Authors: Ganiev Bulat , Lutfullin Azat , Muhliev Ilnur , Husainov Ruslan , Garifullin Artur , Postnov Timur , Postnov Anton
Published: October 2019

Today, significant reserves of PJSC TATNEFT are concentrated in the filled-up terrigenous deposits. A feature of these objects is a high zonal heterogeneity, dissection, degraded filtration-capacitive properties, small thickness (no more than 3-4 meters). Effective development of reserves from these facilities is not possible without the use of high-tech methods of stimulation, primarily drilling of horizontal wells with multi-stage hydraulic fracturing (MSHF).

The aim of the work was the search and adaptation of new solutions, among which was the MSHF using "Plug & Perf" technology. The advantages of this technology is that the whole process is performed exclusively using a logging lot and a hydraulic fracturing fleet, which significantly speeds up the process and allows you to work without additional tripping.

This technology allowed the maximum acceleration of multiple fracturing and minimum damaging of the bottomhole zone during the formation davelopment. During the development, the planned values of the flow rate of the fluid were achieved, which made it possible to introduce a small-sized installation into the well. For the further development of the direction of multiple hydraulic fracturing in horizontal wells, development objects and technological solutions have been identified. The experience of using this technology will allow the low-permeability and clayey thin reservoirs to be actively involved in active development, at the same time increasing the efficiency and speed of work on the multi-stage hydraulic fracturing.