bluuebunny/crossref_metadata_2025_split huggingface dataset:
Complex Phase Behavior Study of a Near-Critical Gas Condensate Fluid in a Tight HPHT Reservoir
Authors: Yazkov Aleksandr Viktorovich , Gorobets Vyacheslav Evgen'evich , Surkov Evgeniy Viktorovich , Solovyev Vladimir Vladimirovich , Devyatov Andrey Sergeevich , Vokuev Vladimir Sergeevich , Filippova Yulia Aleksandrovna , Ibadullaev PervizGilal ogly , Indrupskiy Ilya Mikhailovich , Lobanova Olga Andreevna , Yushchenko Taras Sergeevich , Cherneva Nadezhda Yurevna , Alekseeva Yulia Vladimirovna 
Published: September 2020

Abstract
The near-critical initial state of the formation fluid with a unique content of C5+ components in a tight reservoir with high temperature and abnormally high reservoir pressure (AHRP) causes significant difficulties in collecting samples of the formation fluid and assessing their adequacy to the actual reservoir mixture both in composition and identified phase state (gas condensate or oil) and phase behavior.
The paper presents the result of the work of the project multidisciplinary team, which includes specialists from the PJSC «NOVATEK» group of companies and the leading Russian Institute of Oil and Gas Problems (OGRI RAS), of studying the near-critical gas condensate system in a HPHT tightreservoir. The effect of well completion and sampling conditions on the composition, phase state and phase behavior of fluid samples is shown. The influence of formation water and residual liquid hydrocarbons (HC), capillary effects, adsorption, and the specifics of the PVT-model tuning on the dew point pressure, the condensate lossdynamics, and the variation of composition and phase state of the fluid with depth is assessed. The results made it possible to clarify the understanding of the reservoir system,develop a program for further research, and improve the history matching of the flow model.
The performed modeling of various factors in a porous medium for the conditions of the studied reservoir showed that the presence of formation water and capillary effects do not noticeably affect the phase behavior of the fluid, but the possible presence of scattered hydrocarbons and the adsorption / desorption of hydrocarbon components can lead to considerable changes in the dew point pressure and the condensate loss dynamics. The significant influence of the PVT model tuning on the calculated distribution of the initial fluid composition over the reservoir volume is demonstrated, including the position of the gas-oil contact and its type (classical gas-liquid contact or supercritical transition to the liquid state).
Geologically Driven Stochastic Inversion of Seismic Data for Reservoir Characterization in Tyumen Formation
Authors: Pirogova Anastasia Sergeenva , Epov Kirill Alexandrovich 
Published: September 2020

Abstract
Under conditions of the Krasnoleninsky field (hydrocarbon producing territory in Western Siberia), the pay zones of the Tyumen formation are characterized by a thin-layered structure and a high degree of spatial variability of petrophysical and lithological characteristics. Due to the low elastic contrasts of reservoir rocks relative to the embedding sand-clay sediments, their prediction from seismic data is challenging. Additional complications are associated with the presence of a significant amount of coal material in the geological section. Minimizing the uncertainties of the pay zones prediction can be achieved by integration a priori geological information, seismic and well logging data. Geological information includes knowledge on depositional conditions and evolution of the sedimentary basin that manifests in vertical and lateral facies successions and trends. The paper presents results of geologically driven stochastic inversion of 3D seismic reflection data at one block of the Krasnoleninsky fields. The proposed approach is based on the parameterization of the available geological information and its integration with the results of the petrophysical interpretation of the well logging data within the framework of stochastic inversion.
Identification of SAP Sources in Offshore Production Wells in the North Caspian Oilfields
Authors: Shtun Sergei , Senkov Alexander , Abramenko Oleg , Rakitin Mickhail , Nagimov Vener , Trusov Alexander , Sviridov Alexander 
Published: September 2020

Abstract
The well integrity monitoring including Sustained Annulus Pressure (SAP) assessment on offshore stationary platforms in the conditions of a limited number of well slots plays an important role in the development of oilfield with thin oil rims and a massive gas cap. The presence of SAP leads to uncontrolled release of gas or liquid to the surface, disruption the operating condition of the wells and its completion components, that overall can result to severe accidents at the offshore oil and gas production facility. Another difficulty that SAP brings is secondary gas cap accumulation across untargeted reservoir zones that might lead to blowouts in operating wells. To identify the causes of SAP, constant monitoring of annulus pressure, as well as proper diagnostics are needed. One of the most reliable and effective methods for identifying SAP causes is Through-Barrier Diagnostics that able to accurately localize reservoir-sources of SAP behind multiple casing strings in the wells, which helps production engineers further production strategy and weighted workover planning. Conventional diagnostics on identifying SAP sources is significantly limited by complexity of the well construction and downhole equipment. This paper describes using of Through-Barrier Diagnostics on the sources of SAP identification on the ice-resistant stationary platform named after Yuri Korchagin, detailly explains the approach and challenges on real case studies. High precision temperature and passive spectral acoustics play a key role in described technique. Passive spectral acoustics, which have a scanning radius of about a few meters, helps to detect fluid flows in the reservoir and behind casing channels in cracked cement.
Multistage Hydrocarbon-Based Fracturing in Tight Gas Formation
Authors: Astafyev Vladimir , Lushev Mikhail , Mitin Alexey , Plotnikov Alexey , Mironov Evgenii , Legay Alexey , Dubnitskiy Ivan , Zavialov Sergei , Vorobyev Vladislav , Mazhirin Yury , Zolnikov Denis 
Published: September 2020

Summary
In fields where conventional production methods are applied to effectively recover hydrocarbons, well stimulation is a method to obtain additional production or to increase it at later stages of development. Therefore, well stimulation methods and technologies may be improved during field development after evaluating their influence on hydrocarbon recovery. In the case of hard-to-recover reserves for which economically feasible production requires application of well stimulation methods, these technologies should be designed to the maximum extent in the initial stages of field development and subjected to minor adjustments in future. This paper reviews the approach to screening horizontal well completion and stimulation technologies in low-temperature and low-permeable gas reservoirs with minor formation overpressure. It also describes trial application of oil-based frac technology in a vertical pilot well and its adaptation to multi-zone horizontal well conditions.
Results of Implementing An Integrated Approach to Modeling, Planning and Conducting of Hydraulic Fracturing on Bazhenov Shale
Authors: Korobitsyn Dmitri Andreevich , Yanaev Aleksey Mirzoevich , Bochkarev Alexander Vladimirovich , Erofeev Artem Alexandrovich , Prodan Artem Sergeevich , Bukov Oleg Vladimirovich , Migunov Nikolay Mihaylovich , Milkov Alexander Yurievich 
Published: September 2020

Abstract
During the Bazhenov shale development, a new integrated approach to planning the multistage hydraulic fracturing was developed. This approach is applied to each drilled well,thus implementing the strategy of technological experiment, where the well serves as a separate testing ground for testing the developed methods and implementing new technologies.With the help of modern multistage hydraulic fracturing modeling tools, developed jointly with technological partners for the project tasks, a technological experiment plan is drawn up for the well and contains new,potentially effective solutions, as well as the already accumulated experience. In accordance with the developed plan,the multistage hydraulic fracturing operation is modeled, taking into account the geological and geomechanical features of the object, such as lateral and zonal heterogeneity and the existing natural fracture zones.
Using the developed approach, multistage hydraulic fracturing operations were performed on more than 25 wells drilled at the Bazhenov shale, which is equivalent to 450 well operations.During this time, various technological solutions have been developed, tested and implemented,which include the use of new hydraulic fracturing fluid samples, the selection of optimal well perforating scheme,the use of combined proppant packs and hydraulic fracturing using mainly low-viscosity fluids.Active use of specialized software for modeling the hydraulic fracturing process and close cooperation of software developers with hydraulic fracturing engineers has led to the expansion of the functionality of the developed software product, improving its quality, convenience and stability of operation. According to the initial assessment,the implementation of the technological experiment strategy in conjunction with the use of specialized software led to a reduction in drilling hazard mitigation during multistage hydraulic fracturing operations,as well as to an increase in accumulated oil production by an average of 37 %.A database of knowledge and individual,successful technological solutions available for use in similar projects has been created.
Due to the Bazhenov shale unique structure and properties,it was necessary to adapt existing solutions in the industry for conducting multistage hydraulic fracturing in ultra-low layer permeability.The process of searching and creating new technologies, tools for modeling the multistage hydraulic fracturing process and analyzing the results was also successfully initiated. The developed approaches have already shown their effectiveness, and the work results can be replicated on subsequent wells, as well as on similar objects.
Alternative Fracturing Fluids: Expanding the Field of Possible Applications and Properties of Hydrophobically Modified Polyacrylamide
Authors: Aleshina Anna Leonidovna , Shibaev Andrey Vladimirovich , Philippova Olga Evgenievna , Osiptsov Andrei Alexandrovich , Shel Egor Vladimirovich , Paderin Grigory Vladimirovich , Saifutdinov Elnar Faridovich , Churakov Artem Vladimirovich , Fayzullin Ildar Gayazovich 
Published: September 2020

Abstract
In this paper, the properties of an alternative fluid for hydraulic fracturing (HF) technology based on hydrophobically modified polyacrylamide (HM-PAAm) are studied. HM-PAAm forms gels as a result of cross-linking of polymer chains by hydrophobic domains. Such cross-links are strong enough to impart resistance to temperature, but they can break and recombine under external influences, which makes it possible to restore properties after strong mechanical shear stresses. In the work, the influence of polymer concentration, temperature, and shear rate on the rheological properties of the gels was studied and the conditions for producing gels promising for use in hydraulic fracturing technology were determined.
Features of Killing Wells Operating Fractured Formations with Abnormally Low Formation Pressures and High Gas Factor
Authors: Shaydullin Vadim Aleksandrovich , Vakhrushev Sergey Aleksandrovich , Magzumov Niyaz Rinatovich , Yanson Sergey Olegovich , Akhmerov Ilgam Anvarovich 
Published: September 2020

Summary
The article describes the development of a technology meant to kill wells in fractured carbonate reservoirs of the Republic of Bashkortostan with abnormally low reservoir pressure (ALRP) and high gas-oil ratio. Initially, various technologies were tested in wells to solve this problem: invert emulsion muds, biopolymer solutions, crosslinked gels and water-swellable polymers. However, they demonstrated low efficiency. A new killing technology based on a foam-gel system was selected and adapted to the existing conditions to enhance killing efficiency in complicated geological conditions. Successful tests were performed in three wells of reef fields with ALRP.
Persistent domestic circulation of African swine fever virus in Tanzania, 2015-2017
Authors: Yona Clara M. , Vanhee Merijn , Simulundu Edgar , Makange Mariam , Nauwynck Hans , Misinzo Gerald 
Published: September 2020

Abstract
Background: African swine fever (ASF) is a highly fatal viral hemorrhagic disease of domestic pigs that threatens livelihoods and food security. In Africa, ASF virus (ASFV) circulates in sylvatic (transmission between warthogs and soft argasid ticks) and domestic (transmission between domestic pigs) cycles, with outbreaks resulting from ASFV spill-over from sylvatic cycle. A number of outbreaks were reported in different parts of Tanzania between 2015 and 2017. The present study investigated ASFV transmission patterns through viral DNA sequencing and phylogenetic analysis. A total of 3120 tissue samples were collected from 2396 domestic pigs during outbreaks at different locations in Tanzania between 2015 and 2017. Partial sequencing of the B646L (p72) gene was conducted for diagnostic confirmation and molecular characterization of ASFV. Phylogenetic analysis to study the relatedness of current ASFV with those that caused previous outbreaks in Tanzania and representatives of all known 24 ASFV was performed using the Maximum Composite Likelihood model with 1000 bootstrap replications in MEGA 6.0. Results: ASFV was confirmed to cause disease in sampled domestic pigs. ASFV genotypes II, IX, and X were detected from reported outbreaks in 2015-2017. The current ASFV isolates were similar to those recently documented in the previous studies in Tanzania. The similarities of these isolates suggests for continuous circulation of ASFV with virus maintenance within the domestic pigs. Conclusions: Genetic analysis confirmed the circulation of ASFV genotypes II, IX, and X by partial B646L (p72) gene sequencing. The similarities of current isolates to previously isolated Tanzanian isolates and pattern of disease spread suggest for continuous circulation of ASF with virus’ maintenance in the domestic pigs. Although certain viral genotypes seem to be geographically restricted into certain zones within Tanzania, genotype II seems to expand its geographical range northwards with the likelihood of spreading to other states of the East African Community. The spread of ASFV is due to breach of quarantine and transportation of infected pigs via major highways. Appropriate control measures including zoosanitary measures and quarantine enforcement are recommended to prevent ASF domestic circulation in Tanzania.
Meta-analysis reveals severe pollen limitation for the flowering plants growing in the East Himalaya-Hengduan Mountains region.
Authors: Jiang Xianfeng , Xie Yanping 
Published: September 2020

Abstract
Background: Pollen limitation occurs widely and has an important effect on flowering plants. The East Himalaya-Hengduan Mountains region is a global biodiversity hotspot. However, to our knowledge, no study has synthetically assessed the degree of pollen limitation in this area. The present study aims to reveal the degree of pollen limitation for the flowering plants growing on East Himalaya-Hengduan Mountains and to test whether the reproductive features or the elevation is closely correlated with the degree of pollen limitation in this area. Results: We complied data from 76 studies, which included 96 species and 108 independent data records. We found that the flowering plants in this area undergo severe pollen limitation (overall Hedges’ d=2.004, with a 95% confidence interval [1.3264, 2.6743]) that is much higher than that of the flowering plants growing in many other regions around the world. The degree of pollen limitation was tested to determine the correlation with the capacity for autonomous self-reproduction and with the pollination pattern (generalized vs. specialized pollination) of plants. In addition, we found a clear relationship between elevation and the degree of pollen limitation, which indicates that plants might undergo more severe pollen limitation in relatively high places.Conclusions: This paper is the first to address the severe pollen limitation of the flowering plants growing in East Himalaya-Hengduan Mountains region. Moreover, we reveal the positive correlation between elevation and the degree of pollen limitation.
The influence of integrated geriatric outpatient clinics on the health care utility of older people
Authors: Wei Yu-Ju , Hsieh Cheng-Fang , Huang Yu-Ting , Huang Ming-Shyan , Fang Tzu-Jung 
Published: September 2020

Abstract
Background: The number of people aged greater than 65 years is growing in many countries. Taiwan will be a superaged society in 2026, and health care utilization will increase considerably. Our study aimed to evaluate the efficacy of the geriatric integrated outpatient clinic model for reducing health care utilization by older people.Methods: This was a retrospective case-control study. Patients aged greater than 65 years seen at the geriatric outpatient clinic (Geri-OPD) and non-geriatric outpatient clinic (non-Geri-OPD) at a single medical centre were age and sex matched. Data on the number of outpatient clinic visits, emergency department visits, hospitalizations and medical expenditures were collected during the first and second years. A subgroup analysis by Charlson comorbidity index (CCI) and older age (age≧80 years) was performed, and the results were compared between the Geri-OPD and non-Geri-OPD groups.Results: A total of 6723 patients were included (3796 women and 2927 men). The mean age was 80.42 ± 6.39 years. There were 1291 (19.2%) patients in the Geri-OPD group and 5432 (80.8%) patients in the non-Geri-OPD group. After one year of regular follow-up, the Geri-OPD patients showed a significant reduction in the types of drugs included in each prescription (5.62±10.85) and the number of clinic visits per year (18.18 ± 48.85) (P<0.01). After a two-year follow-up, the number of clinic visits, emergency department visits, and hospitalizations and the annual medical costs were still decreased in the Geri-OPD patients. The Geri-OPD patients had more comorbidities and a higher rate of health care utilization than the non-Geri-OPD patients. In the subgroup analysis, patients with more comorbidities (CCI≧2) and an older age (≧80 years) in the Geri-OPD group showed a significant reduction in health care utilization. The Geri-OPD patients also showed a significant decrease in medical utilization in the second year compared with the non-Geri-POD patients.Conclusion: The Geri-OPD reduced medical costs, the number of drugs prescribed, and the frequency of outpatient clinic visits, emergency department visits and hospitalizations in older patients with complicated conditions. The effect was even better in the second year.
Identification of bipolar disorder using a combination of multimodality magnetic resonance imaging and machine learning techniques
Authors: Li Hao , Cui Liqian , Cao Liping , Zhang Yizhi , Liu Yueheng , Deng Wenhao , Zhou Wenjin 
Published: September 2020

Abstract
Background: Bipolar disorder (BPD) is a common mood disorder that is often goes misdiagnosed or undiagnosed. Recently, machine learning techniques have been combined with neuroimaging methods to aid in the diagnosis of BPD. However, most studies have focused on the construction of classifiers based on single-modality MRI. Hence, in this study, we aimed to construct a support vector machine (SVM) model using a combination of structural and functional MRI, which could be used to accurately identify patients with BPD.Methods: In total, 44 patients with BPD and 36 healthy controls were enrolled in the study. Clinical evaluation and MRI scans were performed for each subject. Next, image pre-processing, VBM and ReHo analyses were performed. The ReHo values of each subject in the clusters showing significant differences were extracted. Further, LASSO approach was recruited to screen features. Based on selected features, the SVM model was established, and discriminant analysis was performed.Results: After using the two-sample t-test with multiple comparisons, a total of 8 clusters were extracted from the data (VBM = 6; ReHo = 2). Next, we used both VBM and ReHo data to construct the new SVM classifier, which could effectively identify patients with BPD at an accuracy of 87.5% (95%CI: 72.5-95.3%), sensitivity of 86.4% (95%CI: 64.0-96.4%), and specificity of 88.9% (95%CI: 63.9-98.0%) in the test data (p=0.0022). Conclusions: A combination of structural and functional MRI can be of added value in the construction of SVM classifiers to aid in the accurate identification of BPD in the clinic.
FOXM1 modulates docetaxel resistance in prostate cancer by regulating KIF20A
Authors: Yu Hongbo , Xu Zheng , Guo Maomao , Wang Weiwan , Zhang Weican , Liang Sudong , xu zhibin , Ye Jun , zhu gangyi , zhang chenyang , lin jianzhong 
Published: September 2020

Abstract
Background: Docetaxel resistance affects prognosis in advanced prostate cancer (PCa). The precise mechanisms remain unclear. The transcription factor Forkhead box M1 (FOXM1), which participates in cell proliferation and cell cycle progression, has been reported to affect the sensitivity of chemotherapy. This study explores the role of FOXM1 in PCa docetaxel resistance and its association with kinesin family member 20 A (KIF20A), which is known to promote therapeutic resistance in some cancers.Methods: We monitored cell growth using MTT and colony formation assays, and cell apoptosis and cell cycle progression using flow cytometry. Wound-healing and transwell assays were used to detect cell invasion and migration. mRNA and protein expression were analyzed using quantitative reverse transcription polymerase chain reaction (qRT-PCR) and western blotting. We monitored FOXM1 binding to the KIF20A promoter using the ChIP assay. Tumorigenicity in nude mice was used to assess in vivo tumorigenicity.Results: FOXM1 knockdown induced cell apoptosis and G2/M cell cycle arrest, suppressing cell migration and invasion in docetaxel-resistant PCa cell lines (DU145-DR and VCaP-DR). Exogenous FOXM1 overexpression was found in their parental cells. Specific FOXM1 inhibitor thiostrepton significantly weakened docetaxel resistance in vitro and in vivo. We also found FOXM1 and KIF20A exhibited consistent and highly correlated overexpression in PCa cells and tissues. FOXM1 also regulated KIF20A expression at the transcriptional level by acting directly on a Forkhead response element (FHRE) in its promoter. KIF20A overexpression could partially reverse the effect on cell proliferation, cell cycle proteins (cyclinA2, cyclinD1 and cyclinE1) and apoptosis protein (bcl-2 and PARP) of FOXM1 depletion.Conclusions: Our findings indicate highly expressed FOXM1 may help promote docetaxel resistance by inducing KIF20A expression, providing insight into novel chemotherapeutic strategies for combatting PCa docetaxel resistance.