bluuebunny/crossref_metadata_2025 huggingface dataset:
Oxidative Stress and NO Generation in Cerulein-Induced Acute Pancreatitis in Rats
Authors: Tiemann K. , Schnekenburger J. , Schick V. , Demus U. , Müller-Werdan U. , Atiakshin D. A. , Boecker W. , Samoilova V. E. , Buchwalow I. B.
Published: April 2019

The interaction between nitric oxide (NO) and superoxides is critical in the development of pancreatitis. Previously, we reported on the up-regulation of oxidative stress and NO-synthase (NOS) in the human chronic pancreatitis and in an animal model of pancreatitis induced by pancreatic duct ligation (PDL) in rats. We have shown that oxidative stress runs ahead of NOS up-regulation, which implies that the NO enhancement in the course of pancreatitis is likely to be an adaptive mechanism aimed at maintaining the homeostatic cellular level of the bioactive NO. Here, we report on the expression of NOS and oxidative stress markers (nitrotyrosine and 8-hydroxyguanosine) in the course of cerulein-induced acute pancreatitis in rats. We found that the pattern of superoxides/NO interaction in this model of acute pancreatitis is similar to that in the PDL-induced rat pancreatitis and in the human chronic pancreatitis. It means that cerulein-induced acute pancreatitis like the PDL-induced pancreatitis is a proper model for further studies of pancreatitis development in humans.
Characteristics of the Population of the Rat Thymus CD68+ Cells in Response to Tautomeric Forms of Magnesium Orotate Introduction under Simulated Magnesium Deficiency
Authors: Chuchkova N. N. , Tukmachova K. A. , Smetanina M. V. , Kanunnikova O. M. , Sergeev V. G. , Chuchkov V. M. , Kormilina N. V.
Published: April 2019

he aim of study was to identify a response of the thymus CD68+ cells population to the introduction of tautomeric forms of magnesium orotate under magnesium deficiency.

Material and methods. Magnesium-deficient status in rats was simulated by furosemide loading (30 mg/kg 14 days); then the animals were injected magnesium orotate in the initial oxo-form (Magnerot©, Vervag, Germany) and hydroxy-form obtained by mechanical activation, dosage 50 mg/kg, for 14 days., The density of thymocytes and macrophages was calculated in the subcapsular zone, cortex and brain matter (stained with hematoxylin and eosin) in the thymus, macrophages were studied immunohistochemically using monoclonal CD68 antibodies (Clone PG-M1).

Results. The oxo-form of the drug was shown to lead to an increase in the number of CD68+ cells in the cortex of thymus (1.7 compared with the control) and medulla of thymus (2.3 times), an increase in the intensity of immunofluorescence (22.5%), the appearance of the thymus lobule of large CD68+cells in the cortex and the medulla part with a clearly traced intracellular localization of granules. The introduction of mechanically activated hydroxyl-form was accompanied by an increase in the number of CD68+ macrophages in the cortical area (1.5 times), and cortico-medullary partition (in 1.4 times), but did not affect the cerebral area of the thymus. The overall intensity of fluorescent staining reduced to 27.87±2.2 relative units (RU).

Conclusion. The tautomeric forms of magnesium orotate have a diverse effect on the macrophage population of the thymus: the introduction of the oxo-form is accompanied by a significant activating effect on the CD68+macrophages in contrast to the hydroxyl form having a moderate modulating effect.
Qualidade ambiental e descrição morfométrica de uma microbacia urbana da região hidrográfica do Paraguai
Authors: Almeida Karine Paz de , Santos Maycon Ferreira , Amorim Larissa Soares Alves , Andrade Caroline Simonato Silva , Dores Eliana Freire Gaspar de Carvalho , Caixeta Danila Soares
Published: April 2019

O crescimento desordenado das cidades tem contribuído de forma significativa para degradação do ambiente, sendo, os efeitos sobre os recursos hídricos, na maioria das vezes, irreversíveis. Assim, este estudo objetivou caracterizar morfologicamente a microbacia do São Gonçalo e analisar a qualidade da água desse corpo hídrico por meio de parâmetros físicos (temperatura, cor aparente, turbidez, sólidos totais e condutividade elétrica), químicos (alcalinidade, pH, oxigênio dissolvido, demanda química de oxigênio e demanda bioquímica de oxigênio) e hidráulico (vazão). Para caracterização e verificação da qualidade da água na microbacia, foram realizadas análises de parâmetros morfométricos e determinação de parâmetros físicos, químicos e hidráulico, em 2 pontos amostrais (nascente e foz), durante o período de novembro/2014 a maio/2015. Os resultados apontaram que a microbacia, em condições normais de precipitação é pouco propensa a picos de enchentes. Entretanto, a impermeabilização do solo e a ocupação nas proximidades da Área de Preservação Permanente do córrego, podem contribuir para eventos de cheia, tornando-a suscetível ao escoamento superficial e erosão. Possui potencial dispersor de contaminação nas águas superficiais, fato este evidenciado por meio das análises físicas e químicas, as quais indicaram, em sua maioria, valores acima do permitido pela legislação em vigência. Concluiu-se que a qualidade da água, da nascente e principalmente da foz, da microbacia do córrego São Gonçalo está comprometida.
Farklı desensitizerlerin dentin tübüllerine etkisinin incelenmesi: in vitro taramalı elektron mikroskop analizi
Authors: Nazım Çise , Taner İbrahim Levent
Published: April 2019

Amaç:
Bu in vitro çalışmanın amacı Siyanoakrilat (Periacryl) ve tetra-kalsiyum fosfat
ve dikalsiyum fosfat içerikli desensitizerin (Teethmate) kombine ve tekli uygulamalarının
kalıcılığının ve dentin tübüllerine etkisinin değerlendirilmesidir. Gereç ve Yöntemler:
Gömülü 20 yaş dişlerinden 140 dentin preparatı elde edilmiştir. Preparatlar 7
gruba ayrılmıştır (n=20). Hiçbir uygulama yapılmayan preparatlar “K” kontrol, %6
sitrik asitte 1 dk. bekletilenler PS ( Periacryl ) TS (Teethmate )  PTS(kombine uygulama)   ; 24
saat yapay tükürükte bekletilenler TY (Teethmate ) PY (Periacryl ) PTY (kombine
uygulama ) olarak gruplanmıştır. Uygulama tamamlandığında preparatlar SEM
cihazı kullanılarak morfolojik yapıları, açık dentin tübül alanları ve açık
dentin tübül çapları açısından değerlendirilmiştir. Bulgular:
Açık dentin tübüllerinin alanı kontrol grubuna kıyasla PS, PY, PTS ve PTY
gruplarında azalmıştır (p>0,05). Numunelerdeki açık dentin tübül çap
ortalamaları kontrol grubuna göre PS, PY, PTY, PTS ve TY gruplarında anlamlı
derecede azalmıştır (p>0,05) . Sitrik asit uygulanan gruplarda istatistiksel
olarak anlamlı bir farklılık yokken yapay tükürük uygulanan gruplarda açık
dentin tübül çap ortalaması, PTY grubunda TY grubundan istatistiksel olarak
anlamlı derecede küçüktür (p>0,05) .  

Sonuç:
Periacryl dentin hassasiyet tedavisinde kullanılabilecek bir preparat olmakla birlikte
kombine kullanımda Teethmate ’in kalıcılığını arttırmaktadır.
CHANGES IN MICROMORPHOMETRIC PARAMETERS OF VOIDS ALONG THE PROFILE OF ZONAL SOILS IN EUROPEAN RUSSIA
Authors: Skvortsova E. B. , Abrosimov K. N. , Romanenko K. A.
Published: April 2019

The soils are distinguished by the presence and the profile distribution pattern of such pedogenic parameters as the organic matter content, available pedofeatures, structural state of the soil mass, etc. They differ in the organization of the pore space throughout the soil profile as well. Under discussion are results of computer micromorphometric analysis of fine macropores d = 0.2-2.0 mm in thin sections of vertical orientation from samples taken in genetic horizons of podzolic, soddy podzolic, gray forest soils and chernozems at the territory of European Russia. The profile changes in voids were analyzed using the most informative morphometric parameters such as the total area of the studied voids in thin sections, the content of fissure-like voids and those of vertical and/or horizontal orientation. The soil types under study showed differences in profile distribution of the above parameters. By analogy with the profile of carbonates, salts, organic matter it is proposed to recognize diagnostic profiles of the pore space represented as a system of voids in genetic horizons of the soil profile. Empiric profiles of the pore space reveal a great diversity. The most complicated organization of the pore space is inherent to soddy podzolic soils, the most simple “smoothed” profiles are characteristic of typical chernozems. The expert qualitative typization showed that the eluvial-illuvial and accumulative-eluvial-illuvial types are dominant among the studied empiric profiles of the pore space (42 and 30% respectively), what is explained by prevailing texture-differentiated soils. On the other hand, it makes possible to use the profile of the pore space as a diagnostic parameter of soils and soil formation processes.
Apreciación estética en la Universidad de La Salle: un estudio de caso sobre la mediación del melodrama
Authors: van der Linde Carlos-Germán
Published: April 2019

Este artículo indaga sobre las preferencias literarias de un grupo de estudiantes de diversos programas académicos de la Universidad de La Salle. Para ello se exploran tanto los gustos literarios anteriores a una clase electiva sobre cine y literatura, como las posibles influencias de dicha electiva en la apreciación literaria de los estudiantes participantes. En primera instancia, los resultados obtenidos dejan ver que muchos estudiantes asocian el gusto por una determinada obra dependiendo del nivel de facilidad de esta. Sin embargo, el presente estudio cree haber encontrado razones más profundas para explicar esas elecciones, a saber: una matriz cultural de corte melodramático. El melodrama es un género narrativo ampliamente difundido en el mundo moderno y los estudiantes, por cuanto lectores y espectadores, dominan muy bien sus códigos, sin ser necesariamente conscientes de ello. Así las cosas, la sensibilidad melodramática media en las preferencias estéticas e, incluso, revela el estudio, en la interpretación de diversas esferas de la vida pública.
Treatment of contact burn injury with hypericum perforatum: An experimental study
Authors: CABBAROĞLU Derya , SONGÜR KODİK Meltem , UYANIKGİL Yiğit , ÇETİN UYANIKGİL Emel Öykü , KARABEY Fatih , KIYAN Selahattin
Published: April 2019

Aim: Burns are one of the most difficult physical and psychological traumas that people face. Generally, protection
and prevention strategies from burns are practiced. The young and the elderly are most likely to be affected
tragically. The aim of the present study is to investigate the effect of Hypericum perforatum methanol extractcontaining gel on the healing of burn wounds.
Materials and Methods: Forty male rats of the Sprague-Dawley strain were divided into four groups after a 4x4 area
of their back was shaved, and an experimental burn was created with the direct contact of an aluminum metal stamp
heated in boiling water for 15 seconds. There was no implementation on or treatment of the control group (Group 1).
Burn wounds were irrigated with saline solution (Saline group, Group 2), and silver sulphadiazine 1% (Silverdin®)
cream (Group 3), Hypericum perforatum methanol extract-containing gel (Group 4), and a placebo gel (Group 5)
were applied topically 4 times a day after the contact burn. Histopathological analyses of the burned area were made
at 4, 8, and 24 hours.
Results: The topical use of Hypericum perforatum methanol extract-containing gel in the experimental contact burns,
histologically; resulted in the reduction of collagen discoloration, vascular damage and hair follicle and glandula
sebaceous damage while preserving total number of hair follicles, number of vessels and epidermal thickness
compared to Silver Sulphadiazine 1% (Silverdin®) cream treatment.
Conclusion: Positive effects of topical Hypericum perforatum gel were detected on experimental burns and its use
might have beneficial effects on acute burn wounds.
Graves hastalığında tiroid kanser sıklığının değerlendirilmesi
Authors: YABANOĞLU Hakan , ARER İlker Murat , KOÇER Nazım Emrah , SAKULEN HARGURA Abdirahman , AVCI Tevfik
Published: April 2019

Amaç: Graves hastalığı ve tiroid kanserleri sık görülen hastalıklar olmasına rağmen her iki hastalığın birlikteliği nadir
bir durum olarak karşımıza çıkmaktadır. Bu durumun nadir olmasında hipertiroidinin, tiroid kanserine karşı koruyucu
bir etkisinin olduğunu düşündürmektedir. Çalışmamızda graves hastalığı nedeni ile total tiroidektomi uyguladığımız
hastalardaki tiroid kanser sıklığını belirlemeyi amaçladık.
Gereç ve Yöntem: 2009-2018 yılları arasında graves hastalığı nedeni ile total tiroidektomi yapılan 210 hastanın
dosyası geriye dönük olarak incelendi ve patoloji sonucunda tiroid kanseri tanısı alan 38 hasta demografik ve klinik
özellikleri açısından değerlendirildi.
Bulgular: Hastaların 25’i (%65,8) kadın, 13’ü (%34,2) erkek ve ortalama yaşları 40 (17-68) idi. Ultrasonografik
incelemede tüm hastaların (43/210) %20’ de tiroid bezinde nodül varken, patoloji sonucunda karsinom tespit edilen
hastaların (22/38) %57’sinde nodül mevcuttu. Tiroidektomi yapılan hastaların patolojik incelemelerinde 38 (%18)
hastada tiroid kanseri mevcuttu. Tiroidektomi sonrası 1 hastaya boyun diseksiyonu uygulandı. On iki hastaya
radyoaktif iyot tedavisi uygulandı. Ortalama takip süresi 30 (3-108) ay idi. Takiplerde 2 (%5,2) hastada 12. ve 18.
aylarda tiroidektomi lojunda papiller kanser nüksü görüldü. Her iki hastaya da RAİ tedavisi uygulandı. Takiplerde nüks
izlenmedi.
Sonuç: Graves hastalığı ve tiroid kanser birlikteliği nadir olsa da özellikle graves hastalığı nedeni ile takip edilen ve
yapılan ultrasonografide nodül bulunan hastalarda mutlaka ince iğne aspirasyon biyopsisi yapılmalıdır. Tiroid
dokusunda nodül içeren graves hastalarında cerrahi tedavi seçeneği daha ön planda düşünülmelidir.
Application of Disease Pattern Analysis with Lifestyle Risk Factor for Healthcare Promotion Service
Authors: Young Sung Cho , Seon-phil Jeong
Published: April 2019

Lately, the Critical Pathway(CP) of Electronic Medical Record(EMR) is used to the guideline for a treatment in the public hospital. We propose a healthcare promotion service using disease pattern with lifestyle risk factors. We classify a medical historical patient data with disease codes with lifestyle risk factors (hypertension, diabetes, smoking, overweight, excessive alcohol intake, and low physical activity) to make the lifestyle risk factors through the classification. We finally make the clusters of disease code with lifestyle risk factors using the medical historical data based on EMR's electronic discharge summary data. As the result of that, we do a healthcare recommending service based on the disease pattern with lifestyle risk. We can build a medical help desk of a public hospital to support people as we check into the public hospital; how to get the procedure of curing, the desired curing clinical method for the healthcare promotion service by each disease code, and how to be better our healthcare. We evaluate the performance of the proposed system by experimenting with the datasets collected at the medical center to measure performance and report some experimental results.
Efficacy of Imaging Modalities Assessing Fatty Infiltration in Rotator Cuff Tears
Authors: Tenbrunsel Troy N. , Whaley James D. , Golchian David , Malone Danielle L. , Lima Diego J.L. , Sabesan Vani J.
Published: April 2019

Background:

Fatty atrophy is a diagnosis characterized by the combination of fatty infiltration and muscle atrophy of the rotator cuff. Studies have shown a strong positive correlation between the level of fatty infiltration and the risk of experiencing a chronic rotator cuff tear. Therefore, the purpose of the present study was to review the current literature on radiographic imaging of fatty infiltration and fatty atrophy to better aid surgeons in predicting functional outcome and to help guide patient decisions.

Methods:

We conducted a literature search in PubMed. The exact search queries included “rotator cuff” in the MeSH Terms field; “fatty atrophy,” fatty infiltration,” and “fatty muscle degeneration” in the Title/Abstract field; and various combinations of these searches. We initially found 184 articles using these keywords, including both human and animal studies. The 25 animal studies were excluded, leaving 159 articles. The abstracts of all remaining articles were reviewed and selected on the basis of our inclusion criteria of focusing on patients with rotator cuff tears (preoperatively and postoperatively), fatty infiltration, fatty atrophy, and imaging modalities. We excluded an additional 127 articles, leaving 32 articles that were selected for the final review and inclusion in this study.

Results:

Among 45 shoulder specialists across different studies, interrater agreement for Goutallier staging with use of magnetic resonance imaging (MRI) ranged from 0.24 to 0.82 and intrarater agreement for supraspinatus fatty changes ranged from 0.34 to 0.89. Our review also showed strong positive correlations when assessing the severity of fatty atrophy of the rotator cuff between MRI and ultrasound or ultrasound modalities such as sonoelastography.

Conclusions:

Increasing fatty infiltration of the rotator cuff is associated with greater repair failure rates and hence poorer overall clinical outcomes. MRI remains the gold standard for the imaging of rotator cuff tears and postoperative healing. Ultrasound can decrease health-care expenditures associated with the assessment of repair integrity postoperatively, although ultrasound is not as precise and has some limitations compared with MRI.
Inovação na gestão hospitalar: análise dos resultados de eficiência de um hospital português integrado em uma unidade local de saúde
Authors: Farias Sérgio , Nunes Alexandre
Published: April 2019

Objetivo: Verificar se a alteração do formato jurídico do hospital Amato Lusitano e a simultânea integração com a atenção primária gerou melhoria dos resultados de eficiência em seus serviços clínicos. Metodologia: Para avaliar os resultados de eficiência, utilizou-se à técnica da análise envoltória de dados, considerando como insumos os custos e como resultados a produção registrada de cada serviço clínico ao longo de um período de 15 anos. Os dados de custo e produção foram obtidos através do Gabinete de Apoio à Gestão e do Gabinete de Contabilidade do hospital. A amostra incluiu todos os serviços clínicos de internação, imagem e patologia clínica. Resultados: A mudança da gestão pública para a condição corporativa resultou em melhoria nos resultados de eficiência em 16 dos 17 serviços analisados apresentando um aumento médio de 19,0%. Conclusões: A adoção da gestão empresarial e do modelo de unidade de saúde local tem sido benéfica para o desempenho dos serviços clínicos, com melhoria geral nos resultados de eficiência técnica.
Escolhas metodológicas aplicadas aos modelos analíticos e sua influência nos resultados de avaliações econômicas e na tomada de decisão em saúde: um estudo de casos
Authors: Santos Marisa , Trajman Anete , Pinto Márcia
Published: April 2019

As avaliações econômicas são elaboradas com base em modelos teóricos que procuram representar a realidade. Seu objetivo é a alocação eficiente dos recursos disponíveis para a saúde, sendo, portanto, uma exigência para a incorporação de tecnologias em saúde. A literatura sobre falhas e diferenças de métodos que mudem os resultados de estudos de custo-efetividade é escassa. Neste artigo, foi utilizado o desenho de estudo de caso para ilustrar como a escolha de parâmetros e a definição de pressupostos incorporados aos modelos de análise de decisão podem influenciar os resultados e as conclusões das análises de custo-efetividade e custo-utilidade e, por consequência, a alocação de recursos de saúde. Para tanto, pautamo-nos na discussão de três casos, nos quais observamos que a escolha da estimativa da prevalência, da especificidade de um teste e do horizonte temporal gerou resultados de custo-efetividade divergentes. O que motiva as diferentes escolhas pode ser muito diverso; alertamos para o risco das escolhas baseadas em interesses de promover a nova tecnologia.
A New Modelling Approach to Simulate CO2 Movement and Containment Coupled With Geochemical Reactions and Geomechanical Effects for an Offshore CO2 Storage in Malaysia
Authors: Yong Wen Pin , Azahree Ahmad Ismail , M Ali Siti Syareena , Jaafar Azuddin Farhana , M Amin Sharidah
Published: April 2019

This paper presents a two-way coupled modelling approach to simulate CO2 movement and containment with geochemical reactions and geomechanical effects. CO2storage simulation studies cover three main disciplines, reservoir engineering, geochemistry and geomechanics. This new approach of coupled modelling simulation, by simultaneously simulate both effects of geochemistry and geomechanics, is considered as a more representative and better predictive modelling practice.

The integration of geochemistry and geomechanics effects is important for CO2 sequestration modelling. There are a number of published studies on coupled modelling for CO2 storage. However, the majority of the studies has only covered dynamic-geomechanics or dynamic-geochemistry interaction, without considering any direct geomechanics-geochemistry interaction in a reservoir condition. It is crucial to understand the integrated effects when injected CO2 dissolves into formation water and interacts with formation rock. Depending on in-situ conditions, the formation water with dissolved CO2 could weak or strengthen the formation stress due to geochemical reactions of formation minerals. Therefore, coupled modelling is needed to ensure the long-term safetyof CO2containment at a CO2 storage site with the interactions among geomechanical, geochemical and dynamic fluid flow, and especially to understand the slow and not experimentally accessible mineral reactions.

In this paper, a high CO2 content gas field in Malaysia with high temperature (~150°C) and high pressure (~350 bar) has been studied using integrated coupled modelling approach. The simulation input parameters are first investigated and collected from literature and laboratory studies. A two-way coupled modelling simulation with the consideration of geochemistry and geomechanics effects is desirable because it allows the updates of reservoir properties back and forth in every time step. Different CO2trapping mechanisms, long term fate analysis, subsidence and heaving analysis, and changes of porosity and permeability are investigated. The time frame of simulation studies consists of CO2 injection period (15 years) and post CO2 injection period (500 years).

During the first 15 years of CO2 injection, 95% of injected CO2 is structurally trapped, 4% of CO2is soluted in formation water and 1% is trapped by mineralization. About 0.04m of heaving is observed at the injection area while about 0.05m of subsidence is observed at the production area. In the investigation of long-term CO2fate, it is observed that CO2 gas will be trapped between the lighter hydrocarbon gas layer and aquifer due to density difference.
Microstructural Imaging and Characterization of Organic Matter Presented in Carbonate Oil Reservoirs
Authors: Ivanova Anastasia , Orlov Denis , Mitiurev Nikolai , Cheremisin Alexey , Khayrullin Marsel , Zhirov Alexey , Afanasiev Igor , Sansiev Georgy
Published: April 2019

More than a half of world's hydrocarbon reserves is presented in carbonate reservoirs. Conventional waterflooding leads to inefficient oil recovery from these reservoirs, because majority of them have mixed or oil-wet wetting properties. It is well documented in literature, that the main reason of oil wetness of carbonate rocks is adsorbed components from crude oil. Although progress has been made in determination of oil components, which have a tendency to react with carbonates, carbonate reservoirs development still remains challenging. Hence, in this study we investigated the distribution of adsorbed oil components on rock surfaces in order to define their influence on fluids flow through porous carbonate samples.

This work presents the results for several carbonate core samples taken from the oil zone of an oil reservoir, which mostly consist of calcite with the small impurities of magnesite and quartz. The work provides the standard study of pore structure of samples to assess the solvents influence on pore network of samples using μCT; the method of evaluation of the amount of organic matter adsorbed on calcite using Rock - Eval pyrolysis; the visualization of such matter distribution through samples; and also the results of kinetics experiments in order to evaluate the bond disruption energy between organic matter and surface. Studies have shown that combination of pyrolysis and μCT provides comprehensive and improved data about organic matter.
Evaluation of Miscible CO2 WAG/Sandstone Interactions: Emphasis on the Effect of Permeability Heterogeneity and Clay Mineral Content
Authors: Al-Bayati Duraid , Saeedi Ali , Ghasemi Mohsen , Arjomand Eghan , Myers Mathew , White Cameron , Xie Quan
Published: April 2019

Carbon dioxide (CO2) injection has been identified as an important means to achieve hydrocarbon reservoir potential whilst mitigating the greenhouse gas effect. CO2 injection into depleted oil reservoirs is very often accompanied by chemical interactions between the formation rock and in situ formed solute. Sandstone formations were expected to contain less reactive minerals in their composition, compared with carbonate counterparts. However, the evolution of petrophysical parameters may change due to different clay content in different sandstone rocks. In this manuscript, we evaluate possible petrophysical parameter evolution in layered sandstone core sample during miscible CO2 water alternating gas (WAG) injection. The stratified core sample is composed of two axially split half sandstone plugs each with different permeability. Grey Berea, Bandera Brown, and Kirby sandstone were used to represent low, moderate and high clay content, respectively. Core flooding experiments were conducted using CO2, brine (7 wt % NaCl + 5 wt % KCl + 5 wt % CaCl2.2H2O) and n-C10 at a temperature and pressure of 343 K and 17.23 MPa, respectively. Porosity and pore size distribution of the samples were measured using nuclear magnetic resonance (NMR) before and after flooding. In addition, a high-resolution medical X-ray computed tomography (XCT) scanner was used to detect any change in pores along the core sample.

The results showed a reasonable increase in the post-flood porosity about 1.0% as a maximum. The results also revealed that the changes in porosity are correlated reasonably with the clay minerals amount in the sample (i.e. higher clay mineral amount leads to higher evolution). The X-ray CT images and NMR results confirmed changes in pore spaces and pore size distribution across the core sample. These changes possibly attributed to clay minerals migration which released by mineral dissolution and subsequent pore throat plugging. NMR results also revealed that the larger the pore size, accompanied by high clay mineral amount, the higher the evolution. This may be attributed to the higher contact surfaces at these pores with the injected CO2 (in-situ formed carbonic brine).

Our results provide insight into how clay content may affect CO2/sandstone reaction in the presence of permeability/mineralogy heterogeneity. In addition, it highlights the control of clay content on rock petrophysical parameter evolution, thus its significance in modelling CO2 injection in sandstone reservoirs.
Applicability of Models for Liquid Loading Prediction in Gas Wells
Authors: Vieira Cleide , Stanko Milan
Published: April 2019

Liquid loading phenomenon is known as the inability of the produced gas to carry all the co-produced liquid to the surface. Under such condition, the non-removed liquid accumulates at the wellbore resulting in reduction of the production and sometimes cause the death of the well. Several studies were carried out and correlation were developed based on field and experimental data with the aim to predict the onset of liquid loading in a gas well. However, each model provides different indication on the critical gas velocity at which the liquid loading exists. Thus, to have a clear understanding on the difference between most used models, experiments were performed in an upward inclinable pipe section. The 60-mm diameter test pipe was positioned at angles of 30°, 45° and 60° from horizontal. The fluids used were air and light oil. Measurements include fluid velocities and fluid reversal point. High-speed video cameras were used to record the flow conditions in which the onset of liquid loading initiated. Experimental results were compared with existing models by Turner et al. (1969), Barnea (1986), Belfroid et al. (2008), Luo et al. (2014), Shekhar et al. (2017) and with a commercial dynamic multiphase flow simulator from SPT-Group (OLGA2017.1.0®). Prediction using the liquid film models presented acceptable agreement with experimental.
A 3-D Analytical Model for Multi-Stage Fractured Shale Gas Reservoirs with Damaged Fractures
Authors: Zeng Jie , Li Wai , Liu Jishan , Leong Yee-Kwong , Elsworth Derek , Tian Jianwei , Guo Jianchun
Published: April 2019

After performing hydraulic fracturing treatments in shale reservoirs, the hydraulic fractures and their adjacent reservoir rocks can be damaged. Typically, the following fracture damage scenarios may occur: (1) choked fractures with near-wellbore damage; (2) partially propped fractures with unpropped or poorly propped sections within the fractures; (3) fracture face damage; and (4) multiple damage cases. The basic equations of fracture skin factors, which are widely used to depict fracture damage, are derived under steady-state conditions. They are not accurate when the damaged length is relatively long and are not applicable for multiple fracture damage and partially propped fractures. In this paper, a new composite linear flow model is established considering all above-mentioned fracture damage mechanisms, complex gas transport mechanisms, and the stimulated reservoir volume (SRV) of shale gas reservoirs.

The matrix model is modified from de Swaan-O's spherical element model considering the slip flow, Knudsen diffusion, surface diffusion, and desorption. Natural fractures are idealized as a thin layer that evenly covers the matrix. The reservoir-fracture flow model is extended from the seven-region linear flow model with four additional sub-regions to handle single and multiple fracture damage mechanisms. Specifically, the inner reservoir region near the primary hydraulic fracture is treated as the SRV where the secondary fracture permeability is higher than that of other unstimulated dual-porosity regions and obeys a power-law decreasing trend due to the attenuate stimulation intensity within the SRV. The flows in different regions are coupled through flux and pressure continuity conditions at their interfaces.

This model is validated by matching with the Marcellus Shale production data. And the degraded model's calculation matches well with that of the seven-region linear flow model validated by KAPPA software. Type curves with five typical flow regimes are generated and sensitivity analyses are conducted. Results indicate that the presence of the SRV diminishes pressure and derivative values in certain flow regimes depending on the SRV properties. Fracture face damage, choked fracture damage, and partially propped fractures all control specific flow regimes but the fracture face damage shows the smallest influence, only dominating the late fracture linear flow regime and the matrix-fracture transient regime. In the multiple fracture damage case, some typical flow regimes can be easily identified except the partially propped fractures. The field application example further ensures the applicability in dealing with real field data.
Extended Walsh-Towler Algorithm to Compute Black Oil PVT Properties for Volatile Oil Reservoir Fluids
Authors: Almeida Jaime Juan
Published: April 2019

Walsh and Towler in 1995 presented an algorithm to calculate the modified Black-Oil PVT properties (Bo, Rs, Bg and Rv) of gas condensate reservoir fluids using the experimental data from the Constant Volume Depletion (CVD) test combined with the recovery calculations provided by commercial PVT laboratory reports as part of the PVT study. The purpose of the proposed algorithm is to extend the Walsh and Towler method to volatile oil reservoirs fluids.

Walsh-Towler algorithm requires as input parameters the gas compressibility factor, the two- phase compressibility factor, the cumulative produced gas, the cumulative produced oil, the volume fraction of liquid condensate, at each pressure depletion stage of the CVD experiment and the initial gas compressibility factor (Zi). The algorithm requires the initial gas compressibility factor (Zi) to calculate the initial moles of hydrocarbon at the saturation pressure, to calculate the remaining mole fraction of gas at each pressure stage as a fraction of the total moles initially present at the saturation pressure and, combined with the two-phase compressibility factor, for the calculation of the total moles of gas and liquid remaining after each stage of depletion.

For volatile oil samples, the initial gas compressibility factor (Zi) is undefined; to overcome this limitation a modified algorithm is proposed that replaces the use of the two-phase compressibility factor by the wellstream produced cumulative from the CVD experiment where the initial gas compressibility factor, for volatile oil, is not required.

The proposed algorithm can be applied to calculate the Black-Oil PVT properties (Bo, Rs, Bg and Rv) for both Gas condensate and Volatile oil reservoir fluids.

The common practice to calculate the black-oil PVT model is by calibrating an Equation of State and export the modified black-oil PVT properties for both gas condensate and volatile oil reservoir fluids. Walsh and Towler presented a valuable tool, that not requires the use of a calibrated EOS, to calculate the black-oil PVT properties for gas condensate. The proposed algorithm extends the method to volatile oil reservoir fluids. The proposed algorithm is rigorous, direct and simple to use and can be applied to both gas condensate and volatile oil.
Quantifying Geological Uncertainty for Complex Integrated Production Systems with Multiple Reservoirs and Production Networks
Authors: Pathak Varun , Hamedi Yousef , Martinez Oscar , Vermeulen Stephen , Kumar Anjani
Published: April 2019

Integrated production systems models are very valuable for predicting the performance of complex systems containing multiple reservoirs and networks. In addition, the value of quantifying uncertainty in reservoirs and production systems is immense as it can build confidence in operational investments. However, traditionally it has been extremely tedious to incorporate uncertainty assessments in the context of integrated production systems modelling. This has been addressed in the current work with the help of a case study.

In the current work, a complex integrated production systems model is presented - from Pre-Salt carbonates reservoir offshore of Brazil. The model includes multiple reservoirs with unique fluid types and complex fluid blending in the production network, multiphase and thermal effects in flowlines and risers, gas separation, gas processing, gas compression, and re-injection for either pressure maintenance or for miscible EOR.

The operational strategies, well placement, and well and network configurations are often based on a single geological realization. With the case study presented in this paper, an integrated way of quantifying geological uncertainty has been presented. A new multi-user, multi-disciplinary tool was used for this study that removed any discontinuities and inconsistencies that typically occur in such projects when multiple standalone tools are used for individual tasks. When quantifying uncertainty on production, the dependence on a single realization was eliminated as uncertain parameters were identified and used for creating robust probabilistic forecasts. Probability distribution curves were generated to represent the uncertainty in overall production from this asset, and the risk associated with operational investments was minimized.

Typically, an end-to-end uncertainty assessment is missing from the traditional Integrated Modelling workflows. With this new approach, the challenge of achieving a truly integrated uncertainty assessment for integrated reservoir and production models has been addressed successfully.
Advanced Modeling of Horizontal Well Performance Under Different Re-fracturing Designs in Tight Oil Reservoir
Authors: Lei Zhengdong , Yang Xinping , Li Xiaoshan , Hu Die , Wu Yushu , Peng Yan
Published: April 2019

Re-fracturing of a horizontal well is a method to restore the productivity of the well in unconventional reservoirs after the expected production decline. Consequently, a re-fracturing approach may be necessary to improve/enhance production and ultimate recovery. However, there are many challenges for optimizing re-fracturing treatment design, due to lack accurate quantification of depletion-induced pressure and local stress change around fractures. The workflow presented can be applied to study and optimize a re-fracturing job to prevent potentially catastrophic fracture hits during re-fracturing operations.

In this paper, an integrated re-fracturing workflow was created and applied to determine the optimum re-fracturing strategy for multi-wells pad. This comprehensive workflow represents a multidisciplinary approach that integrates complex hydraulic fracture models, geomechanical models, and multi-well production simulation. The approach is able to couple simulated 3D reservoir pressure with a geomechanical model to quantify depletion-induced stress and pressure field change. Then, the altered stress field is utilized as the input for modeling the new fracture system created by the re-fracturing treatment. Two field cases from a tight oil reservoir are evaluated by comparing the model prediction to the pressure response. The model prediction agrees well with the observed pressure response and surface tiltmeter observations. The synthetic cases of interference between wells due to stresses and fracture design (number, placement and timing) are investigated in this work. A systematic sensitivity study is performed on the effects of re-fracturing time, fracturing spacing.

It is shown that quantification of stress field changes during reservoir depletion provides new insights for the design and evaluation of re-fracturing treatments to enhance field development. There is a critical time in the life of the well that protection refrac could help pressurizing the formation directly by increasing pore pressure through fluid injection and indirectly by mechanical dilation of existing fractures. The dynamic changes of stress field can guide the optimization of re-fracturing mode and zipper fracturing to reduce stress shadow effect. The dynamic change of the pressure field optimizes the fracturing fluid volume, which can increases the volume of the fracture transformation and supply formation energy.

The paper presents aN approach in calculating stress changes and dynamic fracture propagation into depleted region over time. Results obtained by this study give better understanding about propagation of new fractures as well as old fractures in re-fracturing process.
Developing a Methodology for Improved Reservoir Management: A Journey from Characterization to Simulation and Back
Authors: Mishra Shubham , Shrivastava Chandramani , Ojha Aditya , Miotti Fabio
Published: April 2019

An important aspect of reservoir management process is monitoring and revising plans and an essential component of reservoir management strategy is integration of technologies (Satter et al. 1994). In revisions of reservoir management plans, very rarely do operators incorporate any other data than the data from newly drilled wells and the field production in between the revisions. Any inference in the inter-well space is an interpolation between the well data, as surface seismic is limited by its resolution, as the calibration data is available only at well level. For an effective reservoir management, especially in the decline phase of the field, a logical integration of technologies to capture maximum heterogeneity in the interwell space can be very advantageous.

Crosswell technologies, that provide high resolution data between a set of wells, but if used individually, are essentially limited to a very small part of the field having multiple wells. Therefore, in order to monitor and revise reservoir management plans, it is important that such technologies are integrated with full-field solutions. This paper describes a methodology that aims to better manage reservoir by logically integration the 3D reservoir model- a full-field solution- and crosswell electromagnetics/crosswell seismic- an interwell solution.
The Feasibility Appraisal for CO2 Injection and Storage in Condensate Gas Reservoir: Mechanism Studies and Case Analysis
Authors: Jia Ying , Shi Yunqing , Huang Lei , Yan Jin , Sun Lei
Published: April 2019

The YKL condensate gas reservoir is one of the biggest condensate gas reservoirs in China and has been developed more than 10years. At present, the combination of subdivision layer, production speed optimization and horizontal well drilling has been the key to economically unlocking the vast reserves of the YKL condensate gas. The primary recovery factor, however, remains rather low due to high capillary trapping and water invasion. While primary depletion could result in low gas recovery, CO2 flooding provides a promising option for increasing the recovery factor.

The objective of this work is to verify and evaluate the effect supercritical CO2 on enhancing gas recovery and analyze the feasibility of CO2 enhance gas recovery (CO2 EGR) of condensate gas reservoir.

Firstly, novel phase behavior experimental procedures and phase equilibrium evaluation methodology for gas-condensate phase system mixed with supercritical CO2 with high temperature were presented. A unique phase behavior phenomena was also reported. Then, CO2 floodingmechanism in condensate gas reservoir was analyzed and clarified based on experiments. Finally, a series of numerical simulation work were conducted as an effective and economical means to maximize natural gas recovery with the lowest CO2 breakthrough by varying strategies, including CO2 injection rate, injection composition, andinjection timing. Meanwhile the CO2 storage volumes of different strategies were calculated.

The results show that higher gas recovery factor can be achieved with CO2 injection through appearing interphase between two fluids, maintaining reservoir pressure, driving gas like "cushion" and controlling water invasion. All strategies have moderate to significant effects on gas production. The control of injection and production ratio needs to be balanced between pressure transient and CO2 breakthrough over the producer to obtain the maximum gas production. The varying injection pressure shows a positive effect of enhancing gas production. Numerical simulation indicated that the recovery of gas reservoir was improved by around 10 percent. The total CO2 storage would be around 30-40% HCPV.

The research showed that CO2 flooding presents a technically promising method for recovering the vast condensate gas while extensively reducing greenhouse gas emissions.
Risk Assessment and Simulation of Injectivity Decline Under Uncertainty
Authors: Chiotoroiu Maria-Magdalena , Clemens Torsten , Zechner Markus , Hwang Jongsoo , Sharma Mukul M. , Thiele Marco
Published: April 2019

Waterflooding can lead to substantial incremental oil production. Implementation of water injection projects requires the project to fit into the risk (defined here as negative outcomes relative to defined project objectives) and uncertainty (defined here as inability to estimate a value precisely) a company is willing to take.

One of the key risks for water injection into a shallow reservoir is injection induced fractures extending into the caprock. If this risk is seen as "Intolerable" in an As Low As Reasonable Practicable (ALARP) analysis a decision may be made to not proceed with the project., In this study we evaluated caprock integrity by conducting simulations of long-term water injection that include the effects of formation damage caused by internal/external plugging, geomechanical stress changes and fracture propagation in the sand and bounding shale.

The risk of fracture growth into the caprock was assessed by conducting Monte-Carlo simulations considering a set of modelling parameters each associated with an uncertainty range. This allowed us to identify the range of operating parameters where the risk of fracture height growth was acceptable. Our simulations also allowed us to identify important factors that impact caprock integrity. To cover the uncertainty in geomechanical reservoir evaluation, the operating envelope is identified such that the risk of the caprock integrity is reduced. This requires introducing a limit for the Bottom Hole Pressure (BHP) including a safety margin.

The limit of the BHP is then used as a constraint in the uncertainty analysis of water injectivity. The uncertainty analysis should cover the various development options, the parametrisation of the model, sampling from the distribution of parameters and distance-based Generalized Sensitivity Analysis (dGSA) as well as probabilistic representation of the results.

The dGSA can be used to determine which parameter has a strong impact on the BHP and hence the project and should be measured if warranted by a Value of Information analysis.

The final development option to be chosen depends on a traditional NPV analysis.
Predicting the Performance of Tight Gas Reservoirs
Authors: Alem Mehdi , Baig Tarik , Muggeridge Ann , Jones Alistair
Published: April 2019

Engineers need to predict the production characteristics from hydraulically fractured wells in tight gas fields. Decline curve analysis (DCA) has been widely used over many years in conventional oil and gas fields. It is often applied to tight gas, but there is uncertainty regarding the period of production data needed for accurate prediction.

In this paper decline curve analysis of simulated production data from models of hydraulically fractured wells is used to to develop improved methods for calibrating decline curve parameters from production data. The well models were constructed using data from the Khazzan field in Oman. The impact of layering, permeability and drainage area on well performance is also investigated. The contribution of each layer to recovery and the mechanisms controlling that contribution is explored.

The investigation shows that increasing the amount of production data used to fit a hyperbolic decline curve does not improve predictions of recovery unless that data comes from many years (20 years for a 1mD reservoir) of production. This is because there is a long period of transient flow in tight gas reservoirs that biases the fitting and results in incorrect predictions of late time performance. Better predictions can be made by estimating the time at which boundary dominated flow is first observed (tb), omitting the preceding transient data and fitting the decline curve to a shorter interval of data starting at tb. For single layer cases, tb can be estimated analytically using the permeability, porosity, compressibility and length scale of the drainage volume associated with the well. Alternatively, tb can be determined from the production data allowing improved prediction of performance from 2-layer reservoirs provided that a) there is high cross-flow or b) there is no cross-flow and the lower permeability layer either does not experience BDF during the field life time or it is established quickly.