bluuebunny/crossref_metadata_2025_split huggingface dataset:
Numerical Simulation of Reservoir Salt Dissolution Using Fully Implicit Scheme Within Isothermal Compositional Model of Hydrocarbon Filtration
Authors: Bogachev Kirill , Milyutin Sergey , Nazarov Vladimir 
Published: October 2018

Abstract
The article addresses the problem of numerical simulation of the salty water properties after the dissolution of hard reservoir salt following water flooding. A new method is being proposed for the simulation of reservoir salt dissolution within the isothermal models of black oil and compositional model of hydrocarbon filtration, based on fully implicit numerical scheme.
As with water flooding of hydrocarbon fields the injected water and the reservoir water differ in salinity, there is a need to simulate mixing waters of different salinity since such key water properties as density and viscosity depend greatly on the concentration of the dissolved salt. An additional source of salinity in the water phase comes from the hard reservoir salt, its dissolution affecting not only water properties but also the overall reservoir characteristics such as porosity and absolute permeability due to the increased pore volume open to fluid filtration.
The newly proposed method for the simulation of reservoir salt dissolution draws significantly on the ideas formulated in paper [2]. For a more specific description of the change in the pore volume in the process of reservoir salt dissolution, the filtration scheme is amplified with the mass conservation equation for reservoir salt. Most hydrodynamic simulators modeling salty water properties rely on a numerical scheme with splitting where salt concentration at each new time step is found after solving a set of equations consisting of the components' mass conservation equation and the volume conservation equation, calculated for the salt concentration at the previous time step. By the virtue of the fact that water density depends greatly on the concentration of dissolved salt, using the splitting scheme results in the failure of the volume conservation equation following recomputation of salt concentration at the new time step. In this paper, the discretization of the filtration system and the reservoir salt mass conservation equation are proposed to be tackled with the fully implicit scheme devoid of the above drawback. Within numerical experiments with test models as well as actual reservoir models, the proposed fully implicit method of simulation of reservoir salt dissolution has proven its high stability and efficiency allowing computation with large time steps.
Not infrequently, in simulating salty water properties the effect of reservoir salt is being ignored despite its significant effect for the reservoir porosity and absolute permeability. In this paper, the newly proposed method adds importantly to the base model of salt water tracing, while its fully implicit realization allows for stability and high numerical efficiency in computation.
Determination of the Optimal Bottomhole Pressure in Order to Reduce the Removal of the Solid Phase in the Weakly Consolidated Reservoir
Authors: Chebyshev Igor , Shapovalova Alina , Zhigulskiy Svetlana , Lukin Sergey 
Published: October 2018

Abstract
The elaboration of weakly consolidated terrigenous collectors is accompanied by considerable removal of the solid particles. At one of the reservoirs of Western Siberia technique of evaluation and forecast of the volume of the removed solid particles on the basis of Finite-element modeling was tested.
Suggested way to evaluate the volume of the removed particles includes multiple stages. Reconstruction of the dynamic, static properties of the deformation and durability with taking into account the textural features of the rock samples. Construction of the 1D geomechanical models in target layer and exceeding coal-measures. Creation of three-dimensional model of mechanical qualities for realization of further calculations for the well which is included in contour of 3D-model. Finite-element modeling of the part of the trunk of the well in poroelastic arrangement for evaluation of plastic effects which are arising in collector - sandstone and non-collector – aleurolite, argillite with fruit her calculation of the volume of the removed solid particles.
It allows to determine the safest bottom hole pressure for the highest possible conservation of the stability of the well type "fishbone".
Experimental and Theoretical Study of Fracture Toughness Effect on Hydraulic Fracture's Geometry
Authors: Dubinya Nikita , Trimonova Mariia , Tyurin Alexander , Golovin Yuri , Zenchenko Evgeny , Samodurov Alexander , Turuntaev Sergey , Fokin Ilya 
Published: October 2018

Abstract
The article is devoted to mathematical and physical modeling of the process of hydraulic fracture initiation and propagation in the material with known physical-mechanical properties. Fracture toughness was the main focus of the research as it is a parameter characterizing the rock's ability to resist fracturing process. This parameter alongside with rock elastic properties and pumping conditions is one of the governing parameters while considering the fracture propagation in terms of mechanics of brittle fracture. The study is aimed at understanding the impact of fracture toughness on geometric properties of a fracture by means of numerical modeling of laboratory experiments of hydraulic fracture propagation in a model material. The strength properties including fracture toughness of the used model material have been studied using the indentation methods. The difference between experimentally observed and numerically calculated (keeping in mind the estimated strength properties) fracture geometry is studied in the paper and the possible reasons for this difference are discussed.
The Strategic and Tactical Value of Geomechanics for Drilling Operational Excellence of ERD Well in Uzen Field
Authors: Chettykbayeva Kamilla , Petrakov Yuriy , Sobolev Alexey , Tatur Olga , Zozulya Andrey , Kalinin Vadim , Miletsky Mikhail 
Published: October 2018

Abstract
The traditional considerations and guidelines regarding well planning were not applicable to the challenges that extended reach well #101 of the Uzen field have presented. On the one hand, the reservoir itself was shallow, highly heterogeneous and structurally complex. On the other hand, the well trajectory involved the long interval placed nearly parallel to the bedding of catastrophically unstable shales.
The importance of geomechanical study and mud weight optimization have become very clear after reaching TD of 295.3mm section. There were no signs of instability while drilling, however the pulling out of hole was impossible without rotation, the overpulls, torque and pressure spikes resulted in fracturing the well and circulation loss, the well conditions imposed the high risk of BHA LIH.
The mud was gradually weighted up from 1.15 sg to 1.40 sg according to geomechanical calculations performed in a short time. After having conditioned the mud and performed several circulation cycles the drilling string was safely extracted out of hole. Due to the highly unstable hole conditions, the decision was to sidetrack the new borehole.
The main adjustment of the new trajectory of well #101 was dropping as much as possible the inclination angle when drilling through shales, at the same time allowing the maximum distance to water-oil contact. The PDM was planned to be used in the interval with high dogleg while where extended intervals of well trajectory went subparallel to bedding, the RSS was preferred, as there was a high need for lower vibrations and better cleaning quality.
The morning meetings included the reports and discussion of all the involved parties: Volga Gas management, mud and drilling engineers, geomechanicists, mud loggers and geologists. The thorough inter-disciplinary analysis was performed before making any decision: routine (time and number of reaming after drilling the stand, tripping speeds, circulation timing and duration) and strategic (trajectory change, geostopping, place to perform sidetrack, completion optimization, etc) too. The holistic approach of risks’ assessment and the proactive management resulted in drilling success of the first horizontal well in the field (2480m MD, 717m TVDSS). It was drilled safely and efficiently, allowing to access the reserves, delay the onset of water production, accelerate time to reach planned production level, and increase cumulative production of oil. The success of the drilling performance was publicly acknowledged by Volga Gas.
Advanced Computer Modelling for Metal-to-Metal Seal in API Flanges
Authors: Patel Harshkumar , Hariharan Hari , Bailey Greg , Jung Gonghyun 
Published: October 2018

Abstract
API flanges maintain integrity through metal-to-metal seal between gasket and flange groove, where sealability depends on contact stresses through bolt makeup-load, tension, fluid-pressure, bending moment. Approaches like API-6AF2 have limitations. With increased deep-water operations, there is an urgent need to understand true sealability/leakage. This requires micro-scale examination of seal. Very few FEA in literature model surface conditions. The objective here has been to develop an analytical model to estimate contact stresses and leakage considering surface topography.
This work presents a novel approach for modelling sealability/leakage in metal-to-metal surfaces. It utilizes a contact-mechanics and a fluid-flow model. Deterministic multi-asperity contact-mechanics model provides quantitative estimation of gasket contact stresses, contact gap, and contact area. The leakage model uses contact gap information and correlates it with hydraulic permeability between gasket and groove surfaces and predicts leakage using fluid flow through porous media equations. User inputs are gasket surface topography, size, material properties, operating pressure, and fluid viscosity. The calculations are performed on a small surface domain and results are then scaled-up to obtain contact load/leakage for the entire flange/gasket.
Various types of artificially generated surfaces were considered in the model and a parametric study was conducted. Effects of surface finishing have been explained by visual representation of model outputs such as contact status, load distribution, and leakage path. It was observed that critical contact stress to achieve complete sealability is highly dependent on surface characteristics. For similar surface topography, leakage rates are primarily a function of surface RMS. For the same RMS, it is more difficult to seal a randomly rough surface than a patterned or uniform one. As expected, it is easier to seal a soft gasket than a harder one. Similarly, it becomes progressively difficult to seal larger flanges.
Parametric studies/analysis can help improve understanding of leakage. The models can be used to understand relative magnitude of challenges in sealing gases/liquids at true viscosities. With further refinement and experimental validation, the models could serve as a design tool that could greatly assist in selecting effective seal and improve well process safety. Further, the presented approach can also be applied to develop leakage models for other metal-to-metal seal applications such as tubular connections, expandables, etc.
Approaches and Instruments for Well Cost Estimation at PJSC Gazprom Neft
Authors: Tretiakov Sergei , Maksimov Yurii , Sobolev Alexey , Sozonenko Gennadii , Khomitskiy Aleksandr , Karachev Arkadiy , Kosolapov Roman 
Published: October 2018

Abstract
In this article is review an experience of PJSC "Gazprom neft" at well cost estimation, methodologies development and building IT instruments for well cost calculation. The process from sketch diagrams to IT realization is presented and this process includes concept phase, transformation of needs to requirements to IT products, methodologies development, development of IT alghoritms, prototyping and verification via testing tools and validation through approbation at production units of company. At the final there are some conclusions about using this alghoritms and tools and future plans.
Tensorial Permeability Obtained from Pore-Scale Simulations as a Proxy to Core Orientation in Non-Aligned Rock Material
Authors: Gerke Kirill , Karsanina Marina , Khomyak Aleksey , Darmaev Bator , Korost Dmitry 
Published: October 2018

Abstract
In order to parameterize hydrodynamic models and optimize hydrocarbon production one needs to obtain as detailed information on flow properties of reservoir rocks as possible. The most critical petrophysical properties such as permeability are obtained from core measurements. Such core samples are usually subdrilled from full-size core material along a number of different directions, which not necessarily coincide with the directions of the major fluid filtration. It is believed that the most accurate data is obtained if subdrilling occurs parallel or perpendicular to bedding within the full-size core material. In this work we calculate the permeability tensor based on pore-scale flow simulations within pore geometries of the carbonate sample obtained using X-ray microtomography imaging. This allowed us to obtain the full tensor and flow directions without any sample orientation knowledge. The technique is promising for any petrophysical studies, as it allows to obtain tensorial petrophysical properties, and can be especially useful in case the original orientation of the core material is not known. We found the simulated permeability tensor to be highly non-symmetrical, which is in agreement with other published results and can be explained by the boundary conditions used for simulations. Additional research is needed to elucidate the influence of boundary conditions on the simulated permeability tensor.
Application of the Combined Real-Time Petrophysical and Geosteering Model to Increase Drilling Efficiency
Authors: Koryabkin Vitaliy , Stishenko Sergei , Kolba Pavel , Tatur Olga 
Published: October 2018

Summary
The complexity of the geological conditions in the places where the wells are currently drilled, as well as a set of tasks to be solved by teams of drilling experts and the challenges to radically increase the efficiency of operations under low oil prices – all these challenges require a comprehensive engineering approach to real-time support of well drilling.
Regarding development of complex high-risk projects with a high degree of uncertainty, an emphasis should be made on creating and using a unified integration platform for various disciplines involved in the drilling process and real-time interaction.
A single unified petrophysical & geosteering simulation environment will make it possible not only to solve the issue of increasing the efficiency and safety of well drilling, but also boost further improvement of the automatic on-line interpretation of log data for drilling horizontal wells.
The article provides basic steps to designing and building a combined model, real use cases, evaluations of implementation efficiency and possible ways of development the methods proposed.
Improvement in Cement Sealing Properties and Integrity Using Conductive Carbon Nano Materials: From Strength to Thickening Time
Authors: Ahmed Shawgi , Ezeakacha Chinedum Peter , Salehi Saeed 
Published: October 2018

Abstract
Cement sheaths are designed to protect the integrity of oil and gas wells by mitigating movement of formation fluids and leaks. A failure of the cement sheath can result in the loss of zonal isolation, which can lead to sustained casing pressure. Gas migration through a cement sheath in the annulus is one of the main challenges that compromises zonal isolation. Failure in cement-casing bonding and micro annulus creation are other huge issues that compromises wellbore integrity. Even though some past studies have shown the application of nanomaterials, very few have conducted full scale tests measuring the compressive strength, thickening time and gas transition time of these materials.
In this study, nanosynthetic graphite with designed expansive properties has been introduced to fresh cement slurry. The expansive properties of nanosynthetic graphite were achieved by controlling the preparation conditions. The material was made from synthetic graphite and has a surface area ranging from 325-375 m2/gram. Several tests including compressive strength, rheology, and thickening time were performed. An addition of only 0.5% nanosynthetic graphite with appropriate reactivity was sufficient to maintain expansion in the cement system, leading to an early compressive strength development. It has excellent thermal and electrical conductivity and can be used to design a cement system with short and long-term integrity. Rheology and thickening time tests confirmed its pumpability. Controlling the concentration of the additive is a promising method that can be used to mitigate gas migration in gas bearing and shallow gas formations.
Prospects for Using the Microbiological Method of Enhanced Oil Recovery
Authors: Bezverkhaya Elena , Trofimov Igor , Karepov Vladimir 
Published: October 2018

Resume
The use of strains of bacteria that destroy aluminosilicates leads to a change in the molecular structure of rocks of a low permeable clay-containing oil-bearing layer. In processed samples, the reduction in silicon content makes up one to five and a half percent, aluminum totals up to twelve percent. A high intensity of biogenic leaching of silicates (including quartz) is noted during the destruction of silicate minerals by cultures of silicate bacteria, in comparison with the abiogenic process. Among the layered silicates and aluminosilicates, the most decomposable were aluminosilicates (clay minerals). The results of the research may be relevant for the development of clay containing oil-bearing formations in Western Siberia and Yakutia, for the restoration of the reservoir's filtration capacity after drilling on a clay basis, and geological and technological measures.
Methodology of Fibers Impact Calculation on Proppant Transport in Hydraulic Fracture
Authors: Badazhkov Dmitry , Plyashkevich Vladimir 
Published: October 2018

Abstract
The paper provides details of two experimental methods that were developed during the study and performance characterization of fiber-assisted stimulation services. The first method is focused on measuring the change in terminal settling velocities of proppant, which changes are caused by fiber material loading to fracturing fluid. The experimental approach allows us to calculate hindered-settling functions and to predict fiber-assisted proppant settling control for some type of fracturing fluids (linear gels). The second method is focused on analysis of thermal stability of degradable fibers. The thermal stability is estimated by direct fiber performance examination immediately after exposure of material to fluid media under specific conditions. A static proppant settling test was applied here as a criterion of the fiber additive's ability to perform. The key output of the fiber stability test is the critical time, which is the limit of material stability time under given conditions. Mathematical processing was based on degradation rate calculations for set temperatures and calculation of critical time at varied temperature as a sum of fixed time stability functions. Validation was done by repeating calculated varied step temperature conditions experimentally and comparing actual fiber stability versus calculated stability.
Based on the obtained experimental data, it was possible to develop an empirical model suitable for integration into hydraulic fracture simulator. As a result, there is reliable tool for estimation of commercial fiber performance in hydraulic fracturing jobs.
Results of the Integrated Analysis of Discovering Undeveloped Reservoirs on the Mature Fields and Future Perspectives
Authors: Bashirov Ayrat 
Published: October 2018

Abstract
This work presents the development of method that allows to discover undeveloped reservoirs on the mature fields. The method was tested on the field located on south side of the West-Kuban trough – the Abino-Ukrainskoe field. This field is characterized by complex geology and final stage of development.
The existing geological model of the field is much-simplified what makes it impossible to solve the problem of localization remaining reserves and planning of well interventions.
The proposed approach is a sequence of actions that is of a general nature, and includes a number of detailed studies based on three types of input information: logging data, core and seismic data.
In the course of the work, the geometrization of the developed highly productive objects (HPO), which are related to the Miocene complex, was done and the promising areas of the HPO were predicted.
Also, the work revises the geological structure of the field and demonstrates the prospects of the Eocene deposits of sediments.
Effects of CEOR Chemicals on Asphaltene Precipitation
Authors: Curren Morgan , Kaiser Anton , Adkins Stephanie , Qubian Ali , Al-Enezi Huda , Sana Heba , Al-Murayri Mohammed , Delshad Mojdeh 
Published: October 2018

Abstract
Enhanced oil recovery methods are appealing to increase oil recovery from reservoirs due to market pressures in times of lower oil price. Chemical enhanced oil recovery (cEOR) methods such as ASP involve the use of alkali, surfactant, and polymer, to create an ultralow interfacial tension (IFT) between microemulsion and oil phases. These chemicals have the potential to interact with asphaltenes in crude oil and may cause either a decrease or an increase in asphaltene deposition. This paper presents an investigation into the effects of ASP chemicals on asphaltene precipitation.
Crude oil, from a cEOR-nominated Kuwaiti reservoir, was analyzed with an ASP formulation that was determined through microemulsion phase behavior experiments. Crude oil, chemical components, and incompatible solvent were added together, and light transmission was measured over a 15-minute period to determine asphaltene precipitation over time.
A blank graph of the crude in incompatible solvent showed a light transmission increase of 36.2% over the test duration indicating asphaltene precipitation. If asphaltenes remain suspended in oil, light transmission remains low and stable from the beginning to the end of the test. Addition of asphaltene inhibitor (AI) to the crude oil prevented asphaltene flocculation which was evidenced by a maximum light transmission of 3.0%, an efficiency of 91.7% dispersability relative to the blank sample. With addition of the ASP formulation, light transmission increased which indicates interaction between (1) chemical species of the ASP formulation with asphaltenes or (2) the alkali in the chemical package altering the pH and causing more asphaltene precipitation from suspension in the crude. Maximum light transmission of oil dosed with the chemical additives is 41.3% which is a decrease in asphaltene inhibition efficiency of 14.1% relative to the blank. With the addition of AI to the crude containing the chemical additives, the maximum light transmission is 6.5% indicating an efficiency of 82% asphaltene dispersability. Results indicate a clear relationship between addition of ASP chemicals and asphaltene precipitation. Conditions will differ for other crude oils and cEOR formulations, but asphaltene scaling issues should be considered for cEOR projects.