bluuebunny/crossref_metadata_2025 huggingface dataset:
Liquidity versus Profitability: A Study on Hindustan Unilever Limited
Authors: Basak Radhagobinda
Published: October 2017

As per the general notion, liquidity should have an opposite relationship with profitability. In case of Hindustan Unilever Limited, it has been observed that with the passage of time, the company was able to improve both its liquidity and profitability. The present paper seeks the reason behind this contradictory result. As per the findings of the paper, intelligent debtors and creditors management helped the company a lot to achieve higher profitability along with higher liquidity.
Segredos escondidos à vista de todos: implicações para a leitura dos códigos de barras nos livros infantis
Authors: Ramos Ana Margarida
Published: October 2017

Pretende-se, com este estudo, proceder a uma análise dos códigos de barras ilustrados em livros infantis, com vista a identificar as implicações para a leitura desta opção de design gráfico. A partir da identificação de um corpus de várias dezenas de livros infantis ilustrados, publicados em Portugal nos últimos anos, identificam-se não só as manipulações visuais e artísticas de que estes elementos são alvo, mas também a forma como a sua leitura, nomeadamente com crianças, pode colaborar no desenvolvimento de competências profundas de leitura, além de permitir compreender a dimensão relevante dos peritextos na construção dos sentidos dos livros.
Rock books: intermidialidade no discurso literário pop
Authors: Laranjeira Antonio Eduardo Soares
Published: October 2017

Este trabalho tem como objetivo tecer uma breve reflexão acerca das relações intermidiáticas em narrativas contemporâneas, mais especificamente entre a literatura e a canção pop. As narrativas que resultam desse contato se inscrevem no âmbito do que Evelina Hoisel e Décio Cruz concebem como discurso literário pop, uma noção que se delineia a partir da convergência entre literatura e outras linguagens, no contexto da sociedade globalizada. Com base no conceito de intermidialidade, segundo Claus Clüver e Irina Rajewski, pretende-se compreender de que maneiras é possível tratar a presença da canção pop na narrativa contemporânea como uma trilha sonora. Para tanto, são analisadas cenas dos romances Go, de Nick Farewell, Álbum duplo: um rock romance, de Paulo Henrique Ferreira e A playlist da minha vida, de Leila Sales, em que a canção pop figura como eixo significativo, tanto no que se refere à configuração estética dos textos, quanto no que tange à representação de subjetividades.
Vertigens do tempo: cinema, pintura, escritura
Authors: Giorgi Artur de Vargas
Published: October 2017

O ensaio propõe rearmar, numa breve genealogia, algumas proposições que, transitando entre o cinema, a pintura e a poesia, dão força a um posicionamento crítico da modernidade e da recorrência de seus pressupostos “progressistas” no mundo contemporâneo. Se certa visão da história sustenta-se na naturalização de uma suposta linearidade progressiva do tempo e da cultura, outras leituras reivindicam uma coincidência de temporalidades dissímeis: uma condição vertiginosa que diz respeito à imagem, à palavra – à escritura – e parece esvaziar qualquer consenso sobre a evolução temporal e histórica.
Pre-operative MRCP: is it necessary before routine laparoscopic cholecystectomy to exclude CBD stone-prospective study in tertiary care hospital
Authors: Rao Ganni Bhaskara , Nayak Samir Ranjan , Teja Sepuri Bala Ravi , Palacharla Reshma
Published: October 2017

Background: Cholelithiasis is a common disease and at present the laparoscopic cholecystectomy is the gold standard treatment. The diagnosis of associated common bile duct stone for patients with gallstones is important for prompt surgical decision, treatment efficacy and patient safety. However, whether upper abdominal ultrasound and Liver function test (LFT) is adequate before doing lap cholecystectomy remains controversial. There are different opinions regarding the routine magnetic resonance cholangiopancreatography (MRCP) to detect the possible presence of common bile duct (CBD) stones before laparoscopic cholecystectomy.Methods: This study was carried on a total of 106 patients who were admitted and treated for gall stone diseases in the Department of General Surgery, GSL General Hospital over a period of 24 months. After admission all cases were subjected for liver function test, USG abdomen and MRCP. The collected observational data was analyzed.Results: Among the 106 patients, a total of 17cases showed concurrent gallstones and choledocholithiasis, 11 cases choledocholithiasis were revealed by ultrasound examination, while 6 cases of choledocholithiasis were not detected by ultrasound examination but were confirmed by MRCP.Conclusions: CBD stone may be missed even in the presence of deranged liver enzymes or dilated CBD in USG abdomen. Hence for patient safety routine preoperative MRCP examination is recommended before doing laparoscopic cholecystectomy to rule out the likelihood of concomitant CBD stones. The cost-effectiveness of such expensive investigation is to be studied further taking into consideration preventive costs and patient morbidity and mortality.
Splenectomy for haematological diseases: comparison between laparoscopic and open procedures
Authors: Gomaa Emad , Khalil Magdy
Published: October 2017

Background: In some hematological diseases, the spleen may become enlarged, inflamed and causes destruction of normal blood elements. Laparoscopic splenectomy (LS) was first prescribed in 1991 by Delaitre et al and since that date, it gained a steadily increasing worldwide agreement as an option for splenectomy in patients with hematological diseases. It was reported that this can be performed safely and effectively, with lower incidence of morbidity and mortality. The objective of the study was to compare laparoscopic with open splenectomy as regard its benefits and hazards in haematological diseases.Methods: This prospective study had been conducted in General Surgery Department, Sohag Faculty of Medicine. The study included patients with haematological diseases indicated for elective splenectomy, during the period from January 2015 to June 2017. Twenty patients were included for open surgery (OS) and 20 cases were included for laparoscopic splenectomy (LS).Results: Surgical time was significantly longer in LS than OS group. There was significant correlation between surgical time and splenic size in both groups. Most of the LS patients had been operated upon using the anterior approach (65%). Hospital stay after operation in the LS group was much less than the OS group. Return of off-bed activities, bowel movements, oral intake and drain removal were longer but not significantly different compared to LS figures.Conclusions: Laparoscopic splenectomy for haematological indications can be done safely for the properly selected patients with less blood loss and hospital stay but it requires more operative time as compared to conventional splenectomy.
Entendendo o contexto e o papel da Atenção Básica na Saúde Mental
Authors: Maeyama Marcos Aurélio , Dilda Guilherme Dalcin , Da Ros Marco Aurélio , Barbosa Tatiane Muniz
Published: October 2017

Apesar da clareza das diretrizes do Ministério da Saúde, a oferta de serviços de saúde mental, na Atenção Básica e na Especializada, ainda está centrada na consulta médica, individualizada, na qual a prescrição de medicamentos é o instrumento básico do atendimento, prevalecendo uma atenção limitada, com medicalização do sofrimento. O presente estudo buscou identificar o papel da Atenção Básica na Saúde Mental. Para tanto, utilizou-se de abordagens qualitativas, com a técnica da triangulação de dados. Foram entrevistados 7 profissionais da Atenção Básica e 3 experts na área de Atenção Básica e Saúde Mental. Os dados foram analisados pela técnica de conteúdo temático. A partir das falas dos entrevistados identificaram-se três categorias temáticas: Formação Profissional; Organização dos Serviços de Saúde; e, Papel da Atenção Básica. As mudanças necessárias devem ter, na gestão, a instância facilitadora do processo, especialmente na reorganização da Atenção Básica, incluindo nesta, o respeito pelo número máximo de usuários por área de abrangência, a organização e incentivo às ações de educação permanente, além da integração em rede dos pontos de atenção.
FORMAÇÃO, COMUNICAÇÃO E EDUCAÇÃO PÓS-BOLONHA: um novo futuro?
Authors: Mota Luis Carlos Martins de Almeida , Porto Junior Francisco Gilson Rebouças , Miranda Cynthia Mara , Machado Sandra de Souza
Published: October 2017

Chegamos a conclusão do terceiro ano editorial da Revista Observatório com chave de ouro: durante esse período tivemos diversos avanços na estrutura editorial, que permitiu pensar a revista além do que é feito no momento. Tivemos a agregação de novos atores: na revisão linguística (em português, inglês, espanhol e francês); na edição de mídias sociais que tornou nossa página no Facebook mais visível (passando de 2 mil curtidas!); na edição de metadados, onde voluntários que se debruçam para melhorar os mecanismos de pesquisa na revista e na indexação; e, novos indexadores, que atualizam o conteúdo da revista nos vários espaços de presença da revista. Todo esse sistema alimentado por voluntários dos vários cantos do Brasil e do Exterior!
Nesse número publicamos dois dossiês temáticos: o primeiro intitulado Processos formativos, Comunicação e Educação Pós-Bolonha, organizado pelos professores Luis Carlos Martins de Almeida Mota (Coimbra, Portugal) e Francisco Gilson Rebouças Porto Junior (Palmas, Brasil); o segundo intitulado Mulher e Mídia 2, organizado pelos professores Sandra de Souza Machado (Brasília, DF) e Cynthia Mara Miranda (Palmas, Brasil), dá continuidade a temática da mulher e a presença na mídia.
DIVERSITY OF MEDICINAL PLANTS AND ANTHROPOGENIC THREATS IN THE SAMBURU CENTRAL SUB-COUNTY OF KENYA
Authors: Gafna Dikko J. , Dolos Klara , Mahiri Ishmael O , Mahiri Joseph G. , Obando Joy A.
Published: October 2017

Background: Traditional herbal medicine has been a constant source of substances for curing and preventing a variety of

ailments. Biodiversity of medicinal plants and effects of human activities on availability of traditional herbal medicine have

continuously received just a cursory treatment. This study sought to determine the biodiversity of medicinal plants and

evaluate the effects of human activities on availability of traditional herbal medicine among the Samburu pastoral

community in Kenya.

Materials and Methods: A questionnaire survey was addressed to 195 randomly stratified household respondents in four

villages in Samburu Central Sub-county. Transect walks were carried out in the four villages to determine the diversity of

the medicinal plants. Voucher specimens of the medicinal plant species were deposited at Kenyatta University Herbarium.

Results: The species richness comprised of 19 medicinal plants, majority of which grew in the wild but were threatened by

human activities. 56% of the households reported that fire incidences highly affected availability of traditional herbal

medicine, 50% reported that grazing of livestock moderately affected availability of traditional herbal medicine, 46%

reported that building and construction activities moderately affected availability, while 43% and 40% reported that

firewood collection and growing of crops respectively lowly affected availability of traditional herbal medicine among the

Samburu people.

Conclusion: Most of the Samburu people use traditional herbal medicine. However, majority of the medicinal plants are

threatened by anthropogenic factors. This has led to the continued decline of traditional herbal medicine. There is, therefore

need to adopt management strategies that enhance the conservation of these valuable natural resources.
PROTECTIVE EFFECT OF CAMELLIA OLEIFERA ABEL. ON SILICA-INDUCED PULMONARY FIBROSIS IN RATS
Authors: Tian Shenglan , Liu Xiaoliu , Yang Yang , Lv Yang
Published: October 2017

Background: Camellia oleifera Abel. belongs to the family Theaceae and genus Camellia. It is commonly cultivated

in southern China. The seeds of C. oleifera have been reported to exhibit a diversity of pharmacological activities

which include, but are not limited to, antioxidant, anti-cancer and antimicrobial. Pulmonary fibrosis is one of lethal

causes of mortality across the globe and accretion of considerable amount of reactive oxygen species (ROS) in lungs

have been implicated in the onset of this disease. Given the known antioxidant activity of C. oleifera seed extract

(CSE), the present study was designed to evaluate the influence of CSE on the silica-induced pulmonary fibrosis rat

models.

Materials and Methods: Protective effect of CSE was determined in silica-induced pulmonary fibrosis rat models.

Malondialdehyde (MDA), hydroxyproline (HP) and superoxide dismutase 2 (SOD-2) activity were determined by

standard biochemical assays. Histopathological analysis was carried out by H and E staining. Phyto-constituents of

CSE were identified by LC/MS analysis.

Results: The results of this study indicated that CSE lowered the MDA and hydroxyproline content in silica-treated

rats. Additionally, CSE also caused a significant increase in the expression of SOD-2 leading to scavenging of ROS.

Hematoxylin and eosin (H and E) staining of lung tissue sections revealed that CSE maintained the integrity of

parenchymatous cells of lungs and prevented the development of pulmonary fibrosis. To gain insights about the

phytochemical constituents of CSE, LC/MS analysis was carried out and several antioxidant phenolics and flavonoids

were tentatively identified.

Conclusion: Taken together, we conclude that CSE prevents development of pulmonary fibrosis and the protective

effect of CSE may be due to its ability to induce SOD-2 expression and due to the presence antioxidant phytoconstituents
PROTECTIVE EFFECT OF SOME CHELATING AGENTS AND ANTIOXIDANTS ON THE BIOHAZARDS PRODUCED FROM WATER POLLUTION BY HEAVY METALS IN WISTAR RATS: BIOLOGICAL, GENETIC AND HISTOPATHOLOGICAL STUDY
Authors: Baiomy Ahmed A. , Soliman Mohamed Mohamed , Saad Dalia Y. , Hassan Magdy Yassin , Youssef Gehan B. A.
Published: October 2017

Background: Heavy metals that normally cause problems are mercury (HgCl2) and lead acetate (LA). Chelating

and inhibitor agents are the target to treat and overcome metal toxicity. The current study has been carried out to

evaluate the protective effects of N-acetyl cysteine (NAC) and meso 2,3 dimercaptosuccinic acid (DMSA) against

HgCl2 and LA toxicity.

Materials and Methods: Ninety male Wistar rats were divided into nine equal groups. The groups were administered

NAC and/or DMSA in presence or absence of LA (LA; 0.2% in drinking water) or HgCl2 (2 mg/kg BW) for 2

consecutive months. Serum and organs were collected for biochemical, genetic and histopathological changes.

Results: Biochemical results revealed that LA and HgCl2 significantly increased the levels of liver and kidney

biomarkers. Administration of NAC and DMSA considerably improved these altered changes. LA and HgCl2 decreased

serum levels of antioxidants and were ameliorated in NAC and DMSA administered rats. LA and HgCl2 administration

upregulated expression of IL-1β and IL-8 that were normalized by NAC and DMSA. Kidneys of LA and HgCl2 groups

showed intraluminal hyaline casts. Kidneys of DMSA-administrated rats showed mild hydropic degeneration of renal

tubular epithelium in LA and HgCl2 groups. Kidneys of NAC administrated rats showed atrophy of capillary tufts.

Kidneys of LA and HgCl2 administered rats which received DMSA and NAC showed normal glomerular structure.

Liver histopathology showed sever changes that were ameliorated by NAC and DMSA.

Conclusion: Taken together, usage of NAC and DMSA provide significant protection against LA and HgCl2-induced

hepatotoxicity and nephrotoxicity in male Wistar rats.
CAFFEIC ACID PHENETHYL ESTER (CAPE) MEDIATED DECREASE IN METASTASIS OF COLON CANCER CELLS: AN IN VITRO AND IN VIVO STUDY
Authors: Wu Weiqiang , Gao Feng , Song Xi Heng, Feng , Zhao Yong , Xu Ming , Zhang Xin , Yang Zengqiang
Published: October 2017

Background: Caffeic acid phenethyl ester (CAPE) is a phytochemically active component obtained from honeybee hive

propolis. CAPE has been reported to show antimitogenic, anticancer, and other beneficial medicinal properties. Many of its

activities have been reported to be mediated by inhibiting levels of matrix metalloproteinase, that is, MMP-2 and MMP-9.

We hypothesize the effect of CAPE on the metastasis of colon cancer cells in both in vitro and in vivo.

Methods: Cell migration, motility, invasion were evaluated also expression of protein and matrix metalloproteinases

(MMPs) such as MMP-2 and MMP-9 were measured in SW-480 cancer cells in vitro. The cells were exposed to Phorbol

12-myristate 13-acetate (PMA) and were treated with various concentration of CAPE.

Results: The treatment of CAPE caused significant decrease (P
Quando a Casa é a Marquise, o Albergue, a Rua: discursos e políticas sociais para pessoas em situação de rua em Belo Horizonte
Authors: Honorato Bruno Eduardo Freitas , Saraiva Luiz Alex Silva
Published: October 2017

A partir da constatação de que a população em situação de rua é uma questão social que precisa ser problematizada, nesse trabalho se busca compreender como são articulados discursos que subsidiam as políticas sociais para a população em situação de rua na cidade de Belo Horizonte. Considerada-se aqui a população em situação de rua como um grupo social relativamente coeso e minoritário em termos de poder político institucionalmente reconhecido. A partir de uma pesquisa qualitativa que se valeu de entrevistas semiestruturadas associada à observação participante e registro sistemático em diário de campo, foram obtidos subsídios relevantes para a abordagem da temática, material tratado por meio de análise do discurso. As principais categorias de análise concentraram nas pessoas em situação de rua e nas suas intenções, nos motivos que as levaram a residir nas ruas, no controle social e espacial, e na repressão a que estão sujeitos cotidianamente.
Logging Facies Classification and Permeability Evaluation: Multi-Resolution Graph Based Clustering
Authors: Shi Xinlei , Cui Yunjiang , Guo Xuyang , Yang Hongwei , Chen Rongtao , Li Ting , Li Ruijuan , Wang Ruihong , Wang Jian , Meng Li
Published: October 2017

In the process of reservoir parameters evaluation, it is common to use PoroPerm index relationship model to calculate the permeability. Due to the reservoir heterogeneity, the modeling error of this method can be relatively large. The errors in the calculated permeability directly impact the productivity estimation and detailed study of reservoir in the oilfield development and production stage. Therefore, improving the accuracy of the reservoir permeability modeling has been a major challenge in logging research.

In this paper, we propose a new method to improve the accuracy of reservoir permeability modeling using the Multi-Resolution Graph based Clustering. Specifically, we calculate the Neighboring Index (NI) and adapt the graph based multi-resolution clustering algorithm to classify the logging data. The Kernel Representative Index (KRI) is calculated for the clustering results and the optimal logging facies are identified accordingly. Integrating with the information such as well logging data and core thin section image, the correspondence is established between logging facies from the target areas and their lithology. Then, a permeability evaluation model is constructed using the logging facies as the constraints.

The logging facies classification method using Multi-Resolution Graph based Clustering overcomes the shortcomings of traditional clustering algorithm using Graph theory or the k-Nearest Neighbor. The method of this paper can efficiently classify the logging data and identify the optimal facies using the NI and KRI derived from the normalized Euclidian distances of logging data. This method also improves the resolution of the logging facies classification.

Logging facies are comprehensive integrations of reservoir lithology, physical property and pore structure. Proper logging facies classification can show sedimentary environments and reservoir heterogeneity characteristics. Our methods establish a correspondence between the target block well logging data and their lithology through analyzing the logging data combined with core thin section. It can be applied in further and detailed logging study.

Based on the correspondence of logging facies and lithology, we have built different permeability evaluation models under the constraints of logging facies. This model has been successfully applied to evaluate the unconsolidated sandstone permeability in PengLai 25-6 oilfield. Compared with conventional PoroPerm index relationship model, the calculated permeability using our methods has a much higher consistency with the core analysis permeability. The accuracy of permeability evaluation improved significantly and provided reliable permeability parameters for precise estimation of reservoir.
Carbon Monoxide Hazards from Perforating During Plug and Abandonment Operations
Authors: Burky Thomas , Craddock G. G. , Mason Justin , Rios Federico , Harive Kevin
Published: October 2017

The detonation of explosives in the wellbore produces hazardous gas; however, these gases are not typically observed in high concentrations at the surface. Recently, during plug and abandonment (P&A) operations, carbon monoxide (CO) from perforation activities was observed in high concentrations. This paper examines these types of operations to determine root causes and mitigation methods.

The anticipated amount of CO produced by detonation is calculated by both the empirical equation and reaction-equilibrium simulation methods for cyclotetramethylene tetranitramine (HMX), as well as by the simulation method for cyclotrimethylene trinitramine (RDX), hexanitrostilbene (HNS), and 2,6-bis,bis-(pikrylamino)-3,5-dinitropyridine (PYX). The life cycle of this gas from the time of generation through its potential release to the surface is discussed with the intent to reduce its quantity or concentration throughout. Mitigation methods include the incorporation of an oxidizer in the explosive reaction, chemical scavenging in the wellbore, and controlled venting or catalytic conversion at the surface.

Significant quantities of CO are produced by perforating guns, with the proportion increasing for explosives of greater thermal stability until it is the single largest reaction product. During perforation, these gases are usually controlled by gas-handling equipment on the platform; however, the reduced availability of this equipment on the platform at the time of P&A operations is thought to be a contributing factor to the hazard. Another significant factor could be the use of a high circulation rate, which has the effect of increasing the concentration of the gas on the surface. Controlled venting, flaring, and catalytic conversion to carbon dioxide are feasible methods to help mitigate this hazard if conducted in accordance with regulations.

This paper details the life cycle of CO gas generated from perforating activities and discusses how it can be hazardous during P&A operations. In addition, several methods are discussed that can help mitigate this hazard.
Utilizing Managed Pressure Drilling to Overcome Narrow Margins During Liner Running and Cementing Operations
Authors: Gradishar R. , Fancher C. , Ruhl A. , Patil H.
Published: October 2017

In the past several years, managed pressure drilling (MPD) has developed from an emerging technology to become commonplace in many basins and fields. A joint operator / service company team has employed a technique that applies MPD methodology to cementing applications, increasing the probability of achieving successful primary cement jobs. This technique has been termed managed pressure cementing (MPC). This paper illustrates one of the first instances of successful implementation of MPC to run and cement a liner in the Gulf of Mexico (GOM).

In the GOM over the past 4 years, the operator has incurred an average of 6 days of non-productive time (NPT) per primary cementing job failure to perform remedial cement repairs. In the field where MPC was developed, the previous two wells had experienced 25 days of remedial cementing NPT due to failed primary cementing jobs. In each of these cases, losses during cementing prevented achieving adequate top of cement (TOC). The losses were attributed to the narrow margin between wellbore stability (WBS) and fracture gradient (FG).

This paper focuses on cement placement, which is as important as cement formulation to the success of a cement job. Successful cement placement is a function of controlling equivalent circulating densities (ECD) within the design limits of WBS and FG while ensuring that uncontaminated cement fully sweeps the drilling fluid from the borehole to the designed TOC. The MPC job requires significant planning and processes to accurately model running of the liner, the required fluid displacement program, and the execution of the cementing operations. MPC can reduce the overall well cycle time by eliminating NPT due to remedial cementing.
Shift Work Fatigue in the Petroleum Industry: A Proactive Fatigue Countermeasure
Authors: Meijer Koos , Robb Martin , Smit Jasper
Published: October 2017

Obj ectives/Scope

According to a recent survey of over 27,000 people in 22 countries, insomnia (or problems with sleeping) ranks as the second-most frequent health complaint after the common cold. Sleepiness / fatigue in the work place can lead to poor concentration, absenteeism, accidents, errors, injuries, and fatalities; fatigue has also been associated with some of the most notorious modern catastrophes such as the Exxon Valdez oil spill.

Shift workers are exposed to sleep disturbance as an inherent condition of work. When considering that the jobs of shift workers frequently involve safety- and production-critical tasks, managing the risks associated with shift worker fatigue should be an ongoing activity of O&G organizations. This has been identified and is addressed by industry guidance such as API RP 755, which is aimed at locations where shift workers commute to work. In contrast, the system described in this paper specifically addresses offshore locations where off-shift rest is taken offshore.

Methods, Procedures, Process

The innovation described in this paper, Night Fit, is based on solutions already applied at NASA and within the Dutch offshore industry. It is a light treatment method aimed specifically at the offshore shift work environments that optimizes work performance, health and safety by improving sleeping patterns. This has been shown to reduce workforce fatigue and thereby the risk of human errors. Special glasses and energy lights are used which, when applied to individuals on the basis of scientific understanding, has a positive effect on the secretion of sleep hormones and workforce energy levels. This will in turn support effective off-shift recovery and adaptation to shift changes -without the need for medication.

Results, Observations, Conclusions

At a previous project onboard Allseas’ pipe laying vessel ‘Solitaire’ the crew reported feeling less fatigued, more alert, and more energized during their work. The number of shift workers with a sleep quality grade of eight or higher (on a ten-point scale, with ten being highest quality), increased by almost 300% (21% before the intervention, and 62% six months after). In addition, the number of shift workers reporting feeling "very fatigued" during their shift decreased by more than 75%.

These and similar findings indicate that when properly understood, applying simple interventions -specifically, managing light exposure and providing training on the principles of sleep hygiene- contributes to fatigue risk reduction and enhances the performance, health, and safety of shift workers.
CFD Simulation of Critical Sand Deposition Velocity for Solid-Liquid Slurry Flow
Authors: Dabirian Ramin , Mohan Ram S. , Shoham Ovadia
Published: October 2017

Efficient transport of sand or cuttings is of great importance in oil and gas industry and the fluid velocity in these processes should be high enough to keep particles continuously moving along the pipe. This minimum fluid velocity below which particles deposit, defined as the critical velocity, depends on various factors including flow regime, particle size, particle concentration, phase velocities and fluid viscosity. The objective of this study is to investigate the effect of parameters such as particle size and liquid viscosity on solid particle transport in horizontal pipelines using Computational Fluid Dynamics (CFD) simulations and validate the numerical model predictions with experimental data.

CFD simulations have been conducted with a commercially available software, ANSYS-FLUENT. Eulerian model with k-ω SST turbulence closure model is used to simulate the fluid flow while particles are tracked as the Lagrangian phase. In these simulations eddy interaction model is included to consider the effect of flow turbulence on the particle track. The simulations are created for 0.05 m pipe diameter with 4 m length. The simulations are initialized at relatively high fluid velocity, which is gradually reduced until the particle velocity drops below the acceptable critical velocity.

The CFD simulation results are validated with experimental data from literature, Najmi (2015) and Najmi et al. (2016) for two particle sizes and multiple liquid viscosities. It was observed that the critical velocity values for liquid flows are comparable with CFD simulation results. The simulation results show that depending on the flow regimes (laminar or turbulent) and particle size, the critical velocity can demonstrate similar trend with carrier liquid viscosity as that of the experimental data. Also the CFD simulations and experiment results are compared with three models currently used in industry, namely Oroskar and Turian (1980) model, Salama (2000) model and Danielson (2007) model.
Improved Stoneley Wave Inversion Method for Fracture Evaluation
Authors: Collins M. , Hornby B.
Published: October 2017

The conductivity and density of fractures intersecting a borehole strongly influence well productivity, making fracture characterization an important aspect of reservoir management. A Stoneley-wave inversion process is presented to estimate borehole washout volume and fracture conductivity. In addition to identifying conductive fractures, the ability to detect borehole washout volume can impact other well operations, such as cementing or geomechanical property estimation, in situations where placing a caliper tool in the borehole is not desirable.

Low-frequency Stoneley wave reflections are commonly used to locate and evaluate fractures crossing a fluid-filled, open borehole. However, other mechanisms, such as the reflection from bed boundaries or changes in borehole size, can also induce secondary pressure waves. The inversion of reflectivity over a frequency bandwidth can be used to determine whether a secondary wave is likely the result of a conductive fracture, borehole washout, or the combination of both a washout and a fracture. The integration of additional information from other logs, such as borehole images, caliper, slowness, etc., is used to further distinguish fractures from bedding effects.

This paper describes the theoretical considerations and signal-processing techniques used in this integrated approach, and results from the analysis of field data are presented. The inversion bandwidth ranges from a minimum frequency of 300 to 500 Hz to a maximum of several kHz and is automatically adjusted based on data quality. Several wells were studied using forward modeling and numeric inversion. A comparison of inversion results to borehole images and caliper logs shows depth registration errors typically of 0.3 m (1 ft) or less. The inversion of all reflectivity measurements over the specified bandwidth distinguishes borehole washouts (stronger high-frequency response) from conductive fractures (stronger low-frequency response) and thus provides a more reasonable estimate of fracture conductivity compared to conventional wide-band integrated-amplitude reflection analyses.
Interaction of Non-Darcy Flow Regimes Coupled and Pore Volume Compaction in Shale Gas Formations
Authors: Davudov Davud , Moghanloo Rouzbeh Ghanbarnezhad
Published: October 2017

Shale resources have distinctive characteristics, such as micro-scale pore, ultra-low permeability, and complex fluid flow behavior. In order to predict productivity and deliverability in shale complex system, it is crucial to understand porosity and permeability relation. Since pore size distribution in shale formations is stretched down to nano-meters, the system response violates the predictions of Darcy's law. Depending on pore size and gas properties, non-Darcy flow mechanisms such as slip-flow, molecular diffusion, and Knudsen diffusion can affect the matrix deliverability. Although there are several models to predict permeability considering non-Darcy flow mechanisms, the impact of formation compaction has been neglected in calculations. However, correcting for pore volume shrinkage seems crucial for improved accuracy in evaluation of hydrocarbon reserve.

In this work, we analyze different flow regimes coupled with effects of pore volume compressibility for Barnett and Haynesville shale plays. The pore compressibility values are calculated based on Mercury Injection Capillary Pressure (MICP) data. Using our mathematical formulation, we divide the shale matrix into accessible pores and inaccessible part of the rock (IRP) and characterize pore compressibility values as a function of pressure.

As local pore pressure decreases, formation porosity, pore radius, Knudsen number and thus flow mechanisms are subjected to change with time. Hence, a new permeability model (total permeability) for shale matrix is developed which includes Darcy flow, slip flow, molecular diffusion, Knudsen diffusion, surface diffusion, and last but not the least pore compaction. The impact of pore shrinkage on total permeability reduction is analyzed.

Our results indicate that substitution of accessible pore compressibility with total bulk compressibility can significantly change the production behavior. The results suggest that predicted compressibility values for accessible pores appear to be two to up three orders of magnitude greater than bulk compressibility for Barnett and Haynesville samples. Moreover, effects of pore compaction on permeability during pressure depletion seem significant for the samples studied here. Since Non-Darcy flow mechanisms are sensitive to pore radius, permeability values derived based on laboratory conditions are required to be adjusted before upscaling to reservoir condition.
Mitigating Respirable Crystalline Silica with No Engineering Footprint
Authors: Jackson John , Hicks Jeff , Robinson Jamie
Published: October 2017

In June 2016,the Occupational Safety and Health Administration, OSHA, reduced the Permissible Exposure Limit (PEL) and created an Action Level (AL) for respirable crystalline silica (RCS) by half and will require engineering controlsto help mitigate employee exposure. In June 2018, the new RCS PEL of 0.05 mg/m3 averaged over an 8-hour period will apply to hydraulic fracturing and most other industries, and engineering control obligations will commence in June 2021 for hydraulic fracturing operations.

With an average of over one million pounds of silica sand used in horizontal well completions, crystalline silica is a major component of hydraulic fracturing. Multiple proppant transfer points can generate high concentrations of airborne dust, from offloading trucks to being pumped down hole. Engineering controls can be used tomitigate exposure.

A study was conducted at multiple hydraulic fracturing sites to determine if RCS concentrations could be reduced below OSHA's new PEL using engineering controls that do not have an onsite footprint, namely chemically pre-treated sand.During the study, 10 mm nylon Dorr-Oliver (DO) cyclones were used to measure the amount of RCS produced with and without the chemical engineering control in place. The results showed significant reductions in RCS in both personal and area sampling.

Results presented in this paper will show that effective engineering controls, withno footprint on site, exist and can significantly reduceair-borne RCS concentrations. Overall helping mitigate occupational exposures below the revised PEL and often below the Action Level.
Distance of Investigation for Unconventional Reservoirs Could be Misleading
Authors: Tabatabaie S. Hamed , Pooladi-Darvish Mehran , Mattar Louis
Published: October 2017

Distance of investigation equations are often used, explicitly or implicitly, in rate transient analysis. One important application is for estimation of distance to boundary and its use for well-spacing optimization. The concept of radius of investigation has been used successfully in conventional reservoirs, and has been extended to unconventional reservoirs. Here, we clearly demonstrate the inconsistencies that arise from such extension, and develop concepts and methodologies to remedy such inconsistencies. In particular, we confirm that in radial systems, infinite acting behavior as observed at the production well is consistent with infinite-acting behavior in the reservoir. In other words, i.e. deviation from straight-line behavior on specialized plots is observed shortly after a minimal amount of depletion has occurred at the far boundary. This makes use of the concept of radius of investigation straight forward; a concept that suggests there should be an insignificant pressure drop at the radius of investigation. However, this is not the case for linear flow. The transient behavior as observed in production data is NOT consistent with infinite-acting behavior in the reservoir. The deviation from straight-line behavior on specialized plots is observed much later than end of infinite acting in the reservoir, when there is significant depletion in the reservoir. We demonstrate how misleading it would be, if the concept of distance of investigation is extended to this situation. To remedy this, "time of detection" is introduced as a practical way of relating these theoretical concepts to the practical questions of determination of drainage area for well- and fracture-spacing applications. We demonstrate the use of these concepts through a couple of thought experiments.
Effect of Water in Trasnport and Storage of Non-Aqueous Species in Kerogen
Authors: Kazemi Mohammad , Takbiri-Borujeni Ali , Mansouri-Boroujeni Mahdi , Sun Ting
Published: October 2017

The objective for this work is to determine transport coefficients of multicomponent systems in atomistic kerogen models using molecular dynamics simulations. In transport of multicomponent gases, we are specifically interested in investigating the effects of nonmethane species (ethane, water, and carbon dioxide) on diffusion of methane. The kerogen unit models prepared by (Ungerer et al., 2014) are used in this study. Two mixtures, one containing water and one without water, are placed within the kerogen structures. Computed methane-methane diffusion coefficients are approximately one order of magnitude higher than those for other species in both mixtures for all kerogen types. This is due to fact that methane has the lowest adsorption compared with other three species, and therefore its Onsager diffusion coefficients are the highest. Among the other three species, ethane has the highest diffusion coefficients and water demonstrates the lowest Onsager coefficients. High adsorption (and low transport coefficients) of water is due to induced polarity of the pore surfaces that causes water molecules to be preferentially adsorbed to the pore surfaces over other species. Most of species demonstrate higher diffusion coefficients in the mixture containing water than in other mixture. In the absence of water molecules, vacant adsorption sites become available for other species. These sites will be preferably filled by carbon dioxide molecules as they have higher adsorption capabilities compared to alkanes.
Impact of Screen Geometry on Erosional Resistance of Direct Wire-Wrap Screens
Authors: McKeon C. Dalton , Nelson Seth M. , Gallo Federico , Mayer Christian
Published: October 2017

When estimating the erosion damage from passed fines through wire-wrap sand screens, variables such as approach velocity and gap velocity are often considered to be the main design considerations. Additional variables, such as the gap between the screen and base pipe, are often neglected. For the purpose of the experiments presented in this paper, two main objectives were defined. The first objective was to gain a better understanding of the location and progression of erosion in a conventional wire-wrap sand screen. In particular, inspection of the inlet and outlet surfaces of the screen was conducted in order to evaluate the erosion effects on both boundaries. The second objective was to evaluate the erosion effects of allowing flow to pass underneath the screen’s axial rib wires by introducing various standoff distances between the base pipe and the axial rib wires. The selected standoff distances were similar to a drainage layer typically included in metal-mesh type sand screens. To achieve these two objectives, eight experiments were conducted in an erosion test flow loop with varying experimental standoff geometry stack-ups. Any damage to the sand screen was quantified by calculating the specific erosion of the screen, which is the screen’s total mass loss divided by the total mass of particles passed for a given test duration. Photographs of the coupons before and after each test were used to qualitatively identify affected areas of erosion. The results of these experiments and a brief description of the testing approach are provided herein.
An Experimental Study of Non-Equilibrium CO2-Oil Interactions
Authors: Yassin Mahmood Reza , Habibi Ali , Eghbali Sara , Zolfaghari Ashkan , Dehghanpour Hassan
Published: October 2017

In this study, we use a custom-designed visual cell to investigate non-equilibrium CO2/oil interactions under high-pressure and high-temperature conditions. We visualize the CO2/oil interface and measure visual cell's pressure over time. We perform 5 sets of visualization test. The first three tests aim at investigating interactions of gaseous (g), liquid (l), and supercritical (sc) CO2 with the Montney oil. In the fourth test, in order to visualize the interactions at the bulk oil phase, we replace the opaque Montney oil with a translucent Duvernay light oil (LO). Finally, we conduct N2(sc)-Oil test to compare the results with those of CO2-Oil tests.

Results of the first three tests show that oil immediately expands upon injection of CO2 into the visual cell. CO2(sc) leads to the maximum oil expansion followed by CO2l and CO2(g). Furthermore, the rate of oil expansion in CO2(sc)-Oil test is higher than that in CO2(l)-Oil and CO2(g)-Oil tests. We also observe extracting and condensing flows at the CO2(l)-Oil and CO2(sc)-Oil interfaces. Moreover, we observe density-driven fingers inside the LO phase due to the local increase in the density of LO. We do not observe neither extracting/condensing flows nor density-driven mixing for N2(sc)-Oil and CO2(g)-Oil tests, explaining low expansion of oil in these tests. The results suggest that the combination of density-driven natural mixing and extracting/condensing flows enhance CO2(sc) dissolution into the oil phase, leading to fast oil expansion after CO2(sc) injection into the visual cell.
A Mechanism Study of Wettability and Interfacial Tension for EOR Using Silica Nanoparticles
Authors: Jiang Renfeng , Li Kewen , Horne Roland
Published: October 2017

Wettability alteration and interfacial tension (IFT) reduction are two important mechanisms for enhanced oil recovery (EOR). The introduction of nanotechnology from the fields of Biology and Material Science to the application in EOR is emerging because nanoparticles have the potential to alter formation factors like wettability and fluid properties like IFT and viscosity. However, a systematic literature review shows that ambiguity exists regarding whether nanoparticles can change wettability and IFT or not and which component in nanofluid plays a role. In this work, we investigated the effects of bare silica nanoparticles on wettability and IFT using a contact angle goniometer. The results showed that the contact angle measurement on quartz plates had relatively large uncertainty while those on calcite plates showed a clear trend that the smaller the nanoparticle size and the larger the nanofluid concentration, the smaller the contact angle. In addition, silica nanoparticles did not have an effect on IFT. Core flooding experiments showed an increase of 8.7% in oil recovery factor by the use of silica nanoparticles, which support the oil recovery mechanism of wettability alteration.
Securing Long-Term Well Productivity of Horizontal Wells Through Optimization of Postfracturing Operations
Authors: Potapenko D. I. , Williams R. D. , Desroches J. , Enkababian P. , Theuveny B. , Willberg D. M. , Moncada K. , Deslandes P. , Wilson N. , Neaton R. , Mikovich M. , Han Y. , Conort G.
Published: October 2017

Poststimulation operations on multistage hydraulically stimulated horizontal wells producing from conventional and unconventional reservoirs have a major impact on long-term well performance. Most common types of poststimulation services on such wells include plug drillout (PDO) operations and well flowback (WFB) operations. During these operations, the hydraulic fracture system experiences major changes in pressure and flowrate, which may affect the well's long-term productivity. Among the many mechanisms responsible for decrease in well productivity, we highlight 1) the risk of losing the connection between the wellbore and hydraulic fracture system because of the development of an unpropped area; 2) rock destabilization, and 3) the risk of scaling and precipitation.

In this paper, we describe an integrated engineering and operations workflow for optimizing poststimulation operations on horizontal wells by controlling the productive fracture system evolution during the poststimulation period. The approach is based on applying the secure operating envelope (SOE) concept, which provides a set of operating parameters that ensure preservation of the connection between the hydraulic fractures and wellbore. The SOE is defined for each individual well, using a combination of geomechanical and multiphase transport modeling. It accounts for reservoir properties, well completion, and fracture treatment parameters. High-resolution, real-time monitoring of well performance and active control of bottomhole conditions through choke management ensure the well is operated within the SOE. The production objectives combined with the evolution of the SOE enable an overall strategy for poststimulation operations.

The paper outlines how the SOE is constructed. Applications of the proposed approach on horizontal oil and gas wells in unconventional reservoirs in North America are reported, both during well flowback and plug drillout operations. Using the SOE during well flowback helps to predict and avoid a decrease in well production performance caused by excessive proppant flowback which results in creation of near-wellbore pinch points inside hydraulic fractures. Additionally, plug drillout was identified as a critical operation, during which the proppant pack can be destabilized. The associated risk was strongly reduced by applying the SOE concept in combination with high-resolution monitoring.

Based on data obtained from more than 50 operated wells, we conclude that the proposed methodology, including application of geomechanical modeling to poststimulation operations, brings significant opportunities for optimization of well performance and securing long-term well productivity.