bluuebunny/crossref_metadata_2025 huggingface dataset:
Modern state and perspectives of development of digital economy
Authors:   Tashkent State Institute of Oriental Studies, Zhuraev F.S.
Published: April 2021

Analyzed are global tendencies in development of processes of digitalization, impact of pandemic of coronavirus on formation of global digital eco-system. Also researched is development of processes of digital economy in countries of Central Asia, possibilities and potential of Uzbekistan in development of digital economy.
Features of behavior of Russian and American students on social network Facebook
Authors:   Immanuel Kant Baltic Federal University, Krishtal M.I. , Shchekoturov A.V.
Published: April 2021

Presented is the analysis of peculiarities of behavior of Russian and American students in the social network Facebook. The focus of the study is on what activities students of the two countries are most often engaged in, as well as on what motives they motivate when adding users to the personal list of friends. The main method of research is a formalized interview (N = 266). Students of two higher educational institutions located in Kaliningrad (Russia) and Philadelphia (USA) were interviewed. In anticipation of the analysis, according to the functionality, the types of activities on Facebook were highlighted, i.e. social, functional and cognitive. Also forms of activity were divided into public and private according to the nature of their manifestation (open or hidden). The motives for making friends were typologized according to the user’s orientation towards the development of “binding” or “connecting” social capital. As a result of the analysis, it was revealed that students from the United States are more likely to engage in public activities on Facebook than students from Russia, which is expressed in more active commenting on posts, publishing content on their personal page and friends’ pages. Russian students prefer private activities (chat and viewing other people’s pages). The functional type of activity, expressed in the use of gaming and non-gaming applications, turned out to be the most unpopular form of pastime on Facebook among students in both countries. It was also found that students at two universities are more focused on the development of “connecting” social capital. At the same time, for Russian students the dating factor in real life does not act as an important motive for adding friends to the list as for American ones. It is suggested that the basis for the differences discovered are the features of the cultural environments in which students live. The Russian environment involves more cautious participation in public life, the American stimulates social activism. Significant gender differences in peculiarities of student behavior in Facebook network could not be identified.
Teorias pós-coloniais e decoloniais
Authors: Leda Manuela Corrêa
Published: April 2021

Nesse trabalho tenciona-se abordar as convergências e divergências entre as propostas epistemológicas lançadas nas obras Provincializing Europe, de Dipesh Chakrabarty, e Histórias locais/Projetos globais: colonialidade, saberes subalternos e pensamento liminar, de Walter Mignolo. A partir das reinterpretações que esses autores fazem da narrativa hegemônica da modernidade, pretende-se investigar de que modo a proposta de “provincializar a Europa” de Chakrabarty e “o giro decolonial” de Mignolo confrontam o pensamento colonialista moderno, ao resgatar, respectivamente, a experiência subalterna da colonização indiana e latino-americana.
Can mentors of Erasmus student mobility influence the development of future tourism?
Authors: Cvikl Helena , Artič Nataša
Published: April 2021

Purpose – According to the 25th anniversary of Erasmus program and closing of financing scheme 2007 – 2013 together with launch of new Erasmus era between 2014 and 2020, the time for evaluation of Student Mobility has come. In 2011 on Vocational College for Catering and Tourism Maribor the research within Slovenian domestic companies has been done to evaluate Student Mobility for Placements among domestic tourism companies (Zdolšek, R., 2011), this year the research among foreign Erasmus partner companies has been done. The aim of the paper is to compare the results of both studies and to give proposals for improvement of organization of Student Mobility for Placements with aim to foster tourism development in the region. Approach – The data for research has be primal (own researches) and secondary (theory of Erasmus mobility). Data will be preceded by quantitative research method. Findings – The results of the studies have shown that tourism companies home and abroad evaluate the influence of Student Mobility positively and would be more willing to employ the student that has mobility experience than a student without mobility experience, however, there is still much to be done in promoting Erasmus mobility among companies. Originality of the paper – The paper about evaluation of Erasmus mobility open innovation in the field of hospitality will be used for the first time in hotel industry in Slovenia as the solution for overcoming the economic crisis.
Cruise tourism demand forecasting - the case of Dubrovnik
Authors: Pavlić Ivana
Published: April 2021

The purpose – Cruising is nowadays a mass phenomenon since an increasing number of passengers worldwide have been taking part in this form of tourism. Therefore the purpose of this paper is to forecast cruise tourism demand at the level of micro destination. Design/Methodology/Approach – Dubrovnik has become one of the most important and most frequently visited destinations for cruise tourism in the Mediterranean. The rapidly increasing number of passengers on cruise voyages has put Dubrovnik among the leading cruise destinations in the Mediterranean. Dubrovnik is now facing the problem of concentration of a large number of ships and passengers in a short period of time. Consequently, this paper aims at forecasting the number of passengers from cruise ships within the next five year period in order to highlight eventual consequences and the necessity for implementation of a different management policy in accepting cruise ships and passengers at the destination to satisfy the requirements of both the passengers from cruisers and stationary tourists on one side and on the other side to improve the living standards of the local community. For this purpose the seasonal ARIMA model has been used which incorporates both seasonal autoregressive and moving average factor in the modelling process. Findings – With application of the above mentioned model and having in mind that forecasting was carried out under assumption that there will be no significant changes in the existing conditions it is to be concluded the cruise ship passenger arrivals in Dubrovnik area in 2015 will reach 1.294.316 making an increase of 31% in comparison with the year 2011 at an average growth rate of 7.06%. Originality of the research – Research was carried out to indicate the necessity for implementation of the new model of management for passengers from cruise ships by tourism destination management.
Testing a model of destination attachment - insights from tourism in Tanzania
Authors: Mlozi Shogo , Pesämaa Ossi , Haahti Antti
Published: April 2021

Purpose – Transforming experiences is in this paper approached as a destination choice process for adventure tourists. This study seeks to explain conditions that support place identity and place dependence development in Tanzania. The study proposes a testable destination choice model of international visitors to Tanzania. Design/Methodology/Approach – The proposed order of the model is that perceived constraints and satisfaction depend on expectation and travel motivation and that these two may further predict place identity and place dependence. These measures capture our research questions. Visiting tourists to Tanzania were confronted at airport. During August and September of 2010, 700 filled questionnaires were gathered and 504 was usable for further analysis. Final questionnaires were analyzed using SPSS and SEM (AMOS). Main results – The findings support that tourism policymakers and other stakeholders may consider tourists’ behaviors, such as expectations, motivations, perceived constraints and satisfaction with place identity, to be related to destination attachment. Originality of the research – The paper strengthens several theoretical arguments. First, indicating the amalgamation of different tourists’ behaviors formed in a path-dependent order. One stage is planning the travel, another is during their stay and finally when building their attachment. Furthermore, attachment relate to future choices.
Educational Methods to Improve the Ability of Parents to Provide Developmental Care For Premature Infants: A Literatur Review
Authors: Tri Astuti Indra , Glorino Rumambo Pandin Moses
Published: April 2021

Babies born prematurely are at risk of experiencing visual disturbances, hearing loss, disabilities, the risk of infection and even death. Care for premature babies requires serious attention for both health workers and parents. The role of parents is very important both during hospitalization and at home. Therefore, in order to improve the abilities of parents, it is necessary to make educational efforts with the right method.ObjectivesThis literature review aims to provide an overview of educational methods that nurses can use to improve the ability of parents to care for or care for the development of premature babies. The method used is to search for literature that fits the established theme using 5 data based, namely Scopus, ProQuest, Science Direct, Elsevier Clinicaly for Nursing and Web of Science. The strategy used in finding literature that fits the theme and is used in this literature review uses the PICOS framework. Then conducted a review with the PRISMA method. The literature selection results obtained 572 publications, after going through the selection obtained 11 literatures that match the theme, with 11 educational methods. These methods can be grouped into ideas, namely increasing parental involvement during treatment, using technology, stress management and continuous monitoring. The ability of parents to care for premature babies is needed in order to minimize complications in infants, reduce morbidity, avoid disabilities, increase growth and development of premature babies optimally and reduce parental stress levels, increase parental confidence and good parents' self-efficacy. Choosing the right educational method can improve the ability of parents to properly care for and provide developmental care for premature babies.
Portuguese Translation and Validation of the Body-Esteem Scale for Adolescents and Adults (BESAA) in University Students
Authors: Brandão Maria Piedade , Vale Vera , Gomes Margaret , Pereira Anabela
Published: April 2021

Body-Esteem Scale is an assessment tool for adolescents and adults that evaluate three dimensions of self-evaluations of one’s body. Body-Esteem Scale has been translated and validated in some countries since America down to Europe. Lack of translation and reliability evidence in Portugal was detected. This study aimed to translate and test the validity and reliability of the Body Esteem Scale for Adolescents and Adults (BESAA) in students in the context of Portuguese higher educa-tion. A total of 173 students (60.7% are female) with a mean age of 19.7 (standard deviation = 2.2) years participated. Categorical Principal Component Analysis was used to assess the underlying dimensions of BESAA. Construct validity was evaluated through correlation with the Appearance Schemas Inventory – Revised and a three-factor model (“Appearance”, ‘‘Weight’’ and “Attribu-tion’’) was established. Confirmatory factor analysis was performed to verify the construct validity of the instrument. Items that had factor weights (λ)<.40 were removed, as well as those that were considered redundant by the modification indices estimated by the Lagrange Multipliers (LM) method (LM>11, p<.001). We observed high correlations between theoretically similar factors, and low correlations between different factors. The Portuguese BESAA showed adequate validity and reliability.
Numerical Comparisons Between Bayesian and Frequentist Low-Rank Matrix Completion: Estimation Accuracy and Uncertainty Quantification
Authors: Mai The Tien
Published: April 2021

In this paper we perform numerous numerical studies for the problem of low-rank matrix completion. We compare the Bayesian approaches and a recently introduced de-biased estimator which provides a useful way to build confidence intervals of interest. From a theoretical viewpoint, the de-biased estimator comes with a sharp minimax-optimal rate of estimation error whereas the Bayesian approach reaches this rate with an additional logarithmic factor. Our simulation studies show originally interesting results that the de-biased estimator is just as good as the Bayesian estimators. Moreover, Bayesian approaches are much more stable and can outperform the de-biased estimator in the case of small samples. However, we also find that the length of the confidence intervals revealed by the de-biased estimator for an entry is absolutely shorter than the length of the considered credible interval. These suggest further theoretical studies on the estimation error and the concentration for Bayesian methods as they are being quite limited up to present.
Prospective and Hybrid Alternative of Renewable Energy, For a Sustainable Mining
Authors: MALLMA PEREZ ISRAEL , Salazar Vásquez Lita
Published: April 2021

La minería es una industria intensiva en energía que requiere una fuente estable de electricidad. Con el aumento de la demanda de minerales y la disminución de las leyes, se espera que la demanda de energía aumente en un 36% para el 2035. Este aumento de la demanda depende del uso de combustibles fósiles ya que la electricidad producida y comprada en las empresas mineras se basan principalmente en el caso de los combustibles fósiles, los costos de los sistemas de almacenamiento de energía solar y eólica han caído a una escala sin precedentes, lo que alienta a las empresas mineras a probar estas tecnologías.Entre los factores que influyen en el uso de energía renovable, se encuentra el beneficio a la comunidad en la etapa de operación y cierre o post-cierre de un proyecto minero, el siguiente factor es el perfil de consumo eléctrico o demanda es importante para el cálculo de su almacenamiento o no, de las energías renovables a utilizar. Como tercer factor está el cálculo del consumo en los procesos. Los rangos de penetración determinarán si es posible su almacenamiento de energía, y si es posible utilizar control híbrido (solar - eólico), para ello es importante el uso de herramientas digitales como el programa Holmer, es una herramienta importante que técnica y económica.El gobierno debe tener una perspectiva que ayude en los temas regulatorios necesarios para impulsar proyectos de energía renovable con diferentes incentivos e intereses según el contexto minero.
Adolescents, Ambivalent Sexism and Social Networks, A Conditioning Factor in the Healthcare of Women
Authors: Gil Bermejo Jose Luis , Martos Sanchez Cinta , Vazquez Aguado Octavio , García Navarro Esperanza Begoña
Published: April 2021

Despite gender equality being present in the social and political sphere, we still encounter aspects that are characteristic of sexism. Such aspects impact upon gender inequality and different types of violence towards women. The present article aims to examine the behaviour of adolescents from Huelva with regards to ambivalent sexism towards women on social networks and their influence on health. Further, we seek to uncover adolescent’s perceptions with regards to gender differences in the use of social networks, the relationship between sexism and women's emotional well-being was observed. The study sample was formed by young people aged between 14 and 16 years who were residing in rural and urban zones in the south of Spain. A mixed methods approach was taken. At a quantitative level, a sample of 400 young people was recruited. These were administered a questionnaire about sexism which was composed of two scales and has been validated at a national and international level. At a qualitative level, the study counted on 33 young people who participated in in-depth discussions via interviews and discussion groups. The results showed that sexism emerges in adolescence in the analysed sample from the south of Spain. This favoured a digital gender gap and was reinforced through social networks such as Instagram and Snapchat. Rising awareness and a critical view of the aforementioned sexism was shown on the behalf of females, particularly those from urban backgrounds.
Plasma Metabolomic Profiling of Hypertrophic Cardiomyopathy Patients Before and After Surgical Myectomy Suggests Postoperative Improvement in Liver and Kidney Function
Authors: Wolter Nicole L. , LeClair Madison J. , Chin Michael T.
Published: April 2021

Hypertrophic cardiomyopathy (HCM) is a common inherited heart disorder complicated by left ventricle outflow tract (LVOT) obstruction, which can be treated with surgical myectomy. To date, no reliable biomarkers for LVOT obstruction exist. To determine whether metabolomic biomarkers for obstruction can be identified, we conducted metabolomic profiling on plasma samples of 18 HCM patients before and after undergoing surgical myectomy to measure changes in the plasma metabolome in the postoperative state. Plasma was collected approximately 4 weeks before surgery at the preoperative visit and approximately 3 months after the surgery at the postoperative visit. We found that 215 metabolites were altered in the postoperative state (p-value < 0.05). Identified metabolites that were significantly reduced post-myectomy included metabolites of heme, such as bilirubin, and phenylacetylglutamine, a biomarker of urea cycle disorders, which suggests that liver and kidney function are improved in the postoperative state. Markers of arginine metabolism such as homoarginine and dimethylarginine are also decreased in the postoperative state, suggestive of reduction in nitric oxide production, inflammation and heart failure after surgery. 3-hydroxybutyrate (BHBA) was also decreased, suggesting possible increased fatty acid utilization and a return to normal heart function. 12 of these metabolites were notably significant after adjusting for multiple comparisons (q-value < 0.05), including bilirubin, PFOS, PFOA, 3,5-dichloro-2,6-dihydroxybenzoic acid, 2-hydroxylaurate, trigonelline and 6 unidentified compounds, which support improved kidney and liver function and increased lean soft tissue mass. These findings suggest improved organ metabolic function after surgical relief of LVOT obstruction in HCM and further underscore the beneficial systemic effects of surgical myectomy.
Exacerbating Factors for Eating Disorder Risk in Bodybuilding Athletes
Authors: Efthymiou Dimitris , Kokokiris Lampros , Mesiari Christina , Vassilopoulou Emilia
Published: April 2021

The passion of bodybuilding athletes for a symmetric, lean, heavily muscled body leads them to carry out exhausting exercise programs and restrictive eating regimens, sometimes resulting in disordered eating behaviors. This study investigates potential exacerbators on the development of disordered eating in bodybuilding and strength athletes. The study involved 103 Cypriot bodybuilding athletes of both sexes, performing at three levels: professional, recreational and strength athletes. The Eating Attitude Test 26 (EAT-26) and The Three Factor Eating Questionnaire (TFEQ-R21) were used to evaluate disordered eating and eating behaviors respectively. The current study was performed under the auspices of the Hellenic Center of Education & Treatment of Eating Disorders (KEADD). The degree of deviation between the perceived ideal body weight and the actual body weight was associated with increased risk of eating disorder. Athletes who desired a lower body weight recorded higher scores on EAT-26 overall, and the subscales of dieting and bulimia. Cognitive restraint and emotional eating scales of TFEQ-R21 were more pronounced in the non-professional athletes. The emotional eating score was higher in women. There is a need for appropriate sport-specific, gender-specific preventive intervention to deescalate the risk of eating disorder, in both professional and non-professional bodybuilding athletes.
Total Shoulder Arthroplasty Is Cost-Effective Compared with Hemiarthroplasty
Authors: Lapner Peter , Kumar Srishti , van Katwyk Sasha , Thavorn Kednapa
Published: April 2021

Background:

Although outcome studies generally demonstrate the superiority of a total shoulder arthroplasty (TSA) over a hemiarthroplasty (HA), comparative cost-effectiveness has not been well studied. From a publicly funded health-care system’s perspective, this study compared the costs and quality-adjusted life-years (QALYs) in patients who underwent TSA with those in patients who underwent HA.

Methods:

We conducted a cost-utility analysis using a Markov model to simulate the costs and QALYs for patients undergoing either TSA or HA over a lifetime horizon to account for costs and medically important events over the patient lifetime. Subgroup analyses by age groups (≤50 or >50 years) were performed. A series of sensitivity analyses were performed to assess robustness of study findings. The results were presented in 2019 U.S. dollars.

Results:

TSA was dominant as it was less costly ($115,785 compared with $118,501) and more effective (10.21 compared with 8.47 QALYs) than HA over a lifetime horizon. Changes to health utility values after TSA and HA had the largest impact on the cost-effectiveness findings. At a willingness-to-pay (WTP) threshold of $50,000 per QALY gained, HA was not found to be cost-effective. The probability that TSA was cost-effective was 100%.

Conclusions:

Based on a WTP of $50,000 per QALY gained, from the perspective of Canada’s publicly funded health-care system, TSA was found to be cost-effective in all patients, including those ≤50 years of age, compared with HA.

Level of Evidence:

Economic and Decision Analysis Level II. See Instructions for Authors for a complete description of levels of evidence.
Causal Language in Observational Orthopaedic Research
Authors: Varady Nathan H. , Feroe Aliya G. , Fontana Mark Alan , Chen Antonia F.
Published: April 2021

With the increasing availability of large clinical registries and administrative data sets, observational (i.e., nonexperimental) orthopaedic research is being performed with increased frequency. While this research substantially advances our field, there are fundamental limitations to what can be determined through a single observational study. Avoiding overstatements and misstatements is important for the sake of accuracy, particularly for ensuring that clinical care is not inadvertently swayed by how an observational study is written up and described. We have noticed that causal language is frequently misused in observational orthopaedic research—that is, language that says or implies that 1 variable definitively causes another, despite the fact that causation can generally only be determined with randomization. In this data-backed commentary, we examine the prevalence of causal language in a random sample of 400 observational orthopaedic studies; we found that causal language was misused in 60% of them. We discuss the implications of these results and how to report observational findings more accurately: the word “association” (and its derivatives) can almost always replace or reframe a causal phrase.
Gold and Porphyry Cu–Mo Mineralization of the Bumbat Ore Cluster and Its Relationship with the Early Paleozoic Magmatism of the Lake Zone (Western Mongolia)
Authors: Borisenko A.S. , Gas’kov I.V. , Babich V.V. , Borovikov A.A.
Published: April 2021

––Geological, mineralogical, and geochemical studies of copper and gold mineralization in the Bumbat ore district of Mongolia have shown its association with igneous rocks of different ages formed under different geodynamic, geologic, and geochemical conditions. Copper ore occurrences (site 98 and Altan Gadas site) with an age of 518.0 ± 4.9 Ma have similar mineralogical and geochemical features and seem to be related to plagiogranite-porphyry stocks formed at the late island arc stage (524.5 Ma). The ores were deposited from weakly concentrated solutions with a low content of СО2 at 240–230 °С under subsurface conditions. The association of mineralization with plagiogranites, its localization predominantly in veins, and its essentially copper composition, with high contents of Zn, Mn, Ba, and, in some samples, Ag and Bi, permit us to assign this mineralization to the vein quartz–sulfide type. Its commercial value has yet to be assessed. Gold mineralization of the Three Hills and Darvi sites formed later (455.9 ± 4.3 Ma), during the formation of the final granitoid phases at the accretion–collision stage (511–465 Ma). These sites are mineralized crushing zones composed of hydrothermally altered rocks of sericite–quartz composition with veinlet and disseminated (stockwork) sulfide mineralization and gold-bearing quartz veins. The content of gold in the ores varies from tenths to tens of ppm, and its fineness varies from 700 to 1000‰. The ores of both sites have high contents of Cu, Zn, Mn, Ba, and, in places, Mo. Mineralization formed from hydrothermal solutions with TDS = 9.5–12.0 wt.% NaCl eq. at medium temperatures (230–300 °C) under subsurface conditions. The above specific features of gold mineralization are typical of the flank zones of porphyry Cu–(Mo) deposits.
Challenging Issues of the Earth’s History and the Central Asian and Circum-Pacific Tectonics, Geodynamics, and Metallogeny (on the 85th Birthday of Academician Nikolai L. Dobretsov)
Authors: Shatsky V.S. , Metelkin D.V.
Published: April 2021

—This Special Issue celebrates the 85th birthday of Nikolai Leontievich Dobretsov, Full Member of the Russian Academy of Sciences. The opening paper presents a brief outline of the contributions related to the scientific interests of the hero, which, however, far transcend this limited scope. Hardly there is a field in geosciences where Nikolai Dobretsov would not leave a significant footprint. All over the course of his scientific carrier, he has been prolific in generating new ideas, which he shared generously with the colleagues and numerous disciples. Their papers published in this volume concern key issues of the deep structure and general evolution theory of the planet Earth, including various historic aspects of the geomagnetic field, its relation with the gravity field and with the periodicity of geologic processes, as well as global plate tectonics and plume activity through the Earth’s history. The problems of deep structure are discussed for the cases of the Central Asian Orogenic Belt and the magmatic system feeding the Kamchatka volcanoes. The volume is completed with several papers on metallogeny of the Central Asian orogen and the Russian Far East, especially gold mineralization, which was among principal subjects investigated by N. Dobretsov.
Silica Gel Fracturing Fluids an Alternative to Guar Systems that Allows the use of West Texas Produced Water
Authors: Harman Carl , McDonald Michael , Short Paul , Ott William
Published: April 2021

The use of freshwater, near freshwater, or treated water in hydraulic fracturing represents an ever-increasing cost in the Permian Basin. Environmental concerns add to the pressure to develop methods to use significantly higher volumes of produced water in hydraulic fracture fluids. To solve the challenge of viscosifying untreated, high total dissolved solids water a move was made away from organic-based viscosifiers to silica-based technology.

Fumed silica is highly effective as a viscosifier for high-density brines that has demonstrated excellent low-end rheology, exceptional suspending ability, and a nominal filter cake. However, the high cost of fumed silica and operational challenges have precluded commercial adoption. This paper describes thatsimilar rheology is achievable at a fraction of the cost using a silica gel.

The focus of the paper is on the field trials in West Texas where untreated produced water was viscosified with silica gel and run as alternatives to a standard 20 lb/Mgal crosslinked guar fluid made with fresh water. Low cost and operational efficiencies were obtained bypreparingthe silica gel on-location using standard and readily available hydraulic fracturing equipment. Procedures for making the silica gel-based frac fluid were similar to those of making a crosslinked guar fluid.

Field trials have demonstrated that silica-gel carries high loadings of 20/40 mesh sand even at low pump rates. Production data from the trials has varied from exceeding expectations to being similar to existing production results.On a chemical cost basis, silica gel is comparable to a borate-cross-linked guar frac fluid. The economics tip very much in favor of silica gel when factoring in the savings using untreated produced water.
Rapid Completion Design Changes with Fiber Optics
Authors: Tran John-Bosco , Mientka Matthew , Mogck Drew , Stark Price
Published: April 2021

One of the latest developments in permanent fiber optics is ability to install and complete a well in rapidly based on the needs of the program. This paper will present the drivers leading into the operation, the data collected and the completion advances resulting from a permanent fiber conceived and executed in under four weeks. Completion changes were conceived following direct observations of distribution of flow rate, defined in a Uniformity Index. The resulting changes were cost neutral to the overall program but showed improved completion results and well performance.
Ultra-Fast, Pad-Scale Modeling of Hydraulic Fracturing and Depletion for Optimizing Development Plans in the Eagle Ford Play
Authors: Dontsov Egor , Suarez-Rivera Roberto , Panse Rohit , Quinn Christopher , LaReau Heather , Suter Kirke , Hines Chris , Montgomery Ryan , Koontz Kyle
Published: April 2021

As the number of wells drilled in regions with existing producing wells increases, understanding the detrimental impact of these by the depleted zone around parent wells becomes more urgent and important. This understanding should include being able to predict the extent and heterogeneity of the depleted region near the pre-existing wells, the resulting altered stress field, and the effect of this on newly created fractures from adjacent child wells. In this paper we present a workflow that addresses the above concern in the Eagle Ford shale play, using numerical simulations of fracturing and reservoir flow, to define the effect of the depletion zone on child wells and match their field production data. We utilize an ultra-fast hydraulic fracture and depletion model to conduct several hundred numerical simulations, with varying values of permeability and surface area, seeking for cases that match the field production data. Multiple solutions exist that match the field data equally well, and we used additional field production data of parent-child well-interaction, to select the most plausible model. Results show that the depletion zone is strongly non-uniform and that large reservoir regions remain undepleted. We observe two important effects of the depleted zone on fractures from child wells drilled adjacent to the parents. Some fractures propagate towards low pressure zones and do not contribute to production. Others are repelled by the higher stress region that develops around the depletion zone, propagate into undepleted rock, and have production rates commensurate to that from other child wells drilled away from depleted region. The observations are validated by the field data. Results are being used to optimize well placement and well spacing for subsequent field operations, with the objective to increase the effectiveness of the child wells.
Vertical Growth of Hydraulic Fractures in Layered Formations
Authors: Pandey Vibhas J. , Rasouli Vamegh
Published: April 2021

Fracture growth in layered formations with depth-dependent properties has been a topic of interest amongst researchers because of its critical influence on well performance. This paper revisits some of the existing height-growth models and discusses the evaluation process of a new and modified model developed after incorporating additional constraints.The net-pressure is the primary driver behind fracture propagation and the pressure distribution in the fracture plays an important role in vertical propagation, as it supplies the necessary energy for fracture advancement in the presence of opposing forces. The workflow adopted for this study included developing a preliminary model that solves a system of non-linear equations iteratively to arrive at fracture height versus net pressure mapping. The theoretical results were then compared to those available in the literature. The solution set was then extended to a 100-layer model after incorporating additional constraints using superposition techniques.The predicted outcomes were finally compared to the fracture height observations made in the field on several treatments.

A reasonable agreement between model-predicted and observed height was observed when a comparison between the two was made, for most cases.The majority of these treatments were pumped in vertical wells, at low injection rates of up to 8.0 bbl/min (0.021 m3/s) where net pressures were intentionally restricted to 250 psi (1.72 MPa) in order to prevent fracture rotation to the horizontal plane.The leak-off was minimal given the low permeability formations. In some cases, however, the pumping parameters and fluid imparted pressure distribution appeared to dominate. Overall, it was apparent that for a slowly advancing fracture front, which is the case in low injection rate treatments, the fracture height could be predicted with reasonable accuracy. This condition could also be met in high rate treatments pumped down multiple perforation clusters such as in horizontal wells, though fracture-height measurement may not be as straightforward as in vertical wells.

The model developed under the current study is suitable for vertical wells where fracture treatments are pumped at low injection rates. The solid-mechanics solution that is presented here is independent of pumping parameters and can be readily implemented to assist in selection of critical design parameters prior to the job, with a wide range of applicability worldwide.
Novel Deployment of Tracers Leads to High-Confidence Results
Authors: Ramos Claudio R
Published: April 2021

A unique well-tracing design for three horizontally drilled wells is presented utilizing proppant tracers and water- and hydrocarbon-soluble tracers to evaluate multiple completion strategies. Results are combined to present an interpretation of them in the reservoir as a whole, where applicable, as well as on an individual well basis.

The new approach consists of tracing the horizontal well(s) leaving unchanged segments along the wellbore to obtain relevant control group results not available otherwise. The application of the tracers throughout each wellbore was designed to mitigate or counterbalance variables out of the controllable completion engineering parameters such as heterogeneity along the wellbores, existing reservoir depletion, intra- and inter-well hydraulically driven interactions (frac hits) as well as to minimize any unloading and production biases. Completion strategies are provided, and all the evaluation methodologies are described in detail to permit readers to replicate the approach.

One field case study with five horizontal wells is presented. Three infill wells were drilled between two primary wells of varying ages. All wells are shale oil wells with approximately 7,700 ft lateral sections. The recovery of each tracer is compared between the surfactant treated and untreated segments on each well and totalized to see how the petroleum reservoir system is performing. A complete project economic analysis was performed to determine the viability of a chemical additive (a production enhancement surfactant). Meticulous analysis and interpretation of the proppant image logs were performed to discern the cluster stimulation efficiency during the hydraulic fracturing treatments. Furthermore, comparisons of the cluster stimulation efficiency between the two mesh sizes of proppant pumped are also provided for each of the three new unconventional well completions. The most significant new findings are the surfactant effects on the wells’ production performance, and the impact the engineered perforations with tapered shots along the stages had on the stimulation efficiency. Both the right chemistry for the formation and higher cluster stimulation efficiencies are important because they can lead to increased well oil production.

The novelty of this tracing design methodology rests in the ability to generate results with a statistically relevant sample size, therefore, increasing the confidence in the conclusions and course of action in future well completions.
The Effects of Fluid Viscosity and Density on Proppant Transport in Complex Slot Systems
Authors: Bahri Ashtiwi , Miskimins Jennifer
Published: April 2021

The main functions of hydraulic fracturing fluids are to create a fracture network and to carry and place the proppant into the created fractures networks, thus, adding to fracture conductivity. Significant research has been performed to develop ideal fracturing fluid systems. The development focus has mainly been on optimization of a fluid rheology that can transport and place the proppant into the primary and any subsidiary fractures with less damage to the formation and at a lower cost.

The main goal of this work is to add to the understanding and optimization of proppant transport in complex hydraulic fracture networks. Specifically for this study, focus is placed on two different fluids, water-glycerin solution and water-sodium chloride solution, representing varying fluid densities and viscosities. The effects of changing fluid viscosities, densities, proppant densities, proppant sizes, proppant concentrations, and slurry injection rates on proppant transport were then experimentally investigated. This experimental work shows that viscosity has a greater impact on the proppant transport than fluid density does, thus implying a larger impact on the resulting fracture conductivity. The results of this work show that a water-glycerin solution, with a viscosity of 4.3 cp, has significant proppant carrying capacity with proppants delivered uniformly to greater distances. On the other hand, the results show that a water-sodium chloride solution of 9.24 ppg density has less capability to carry the proppant deep into the fractures indicating that viscosity has a greater impact on the proppant transport than fluid density does. The lab results also showed that increasing proppant concentrations and injection rates has a positive impact on proppant transport.
Dry Powder Deliver of Friction Reducers: A Step Change in Slickwater Fracturing
Authors: John Blevins , Van Domelen Mark , West Zach , Rall Jason , Wakefield Drake
Published: April 2021

Since the early development of unconventional resource plays, slickwater fracturing fluids have expanded rapidly and are now the most common type of fluid system used in the industry. Slickwater and viscosifying friction reducer (VFR) fluids consist of polyacrylamide (PAM) polymers and are typically delivered to location in a liquid form such as a suspension or emulsion in a hydrocarbon-based carrier fluid. Recently, advances in dry powder delivery operations have provided unique advantages over the liquid versions of FRs including cost savings and improved health, safety and environmental (HSE) aspects. This paper describes the dry powder delivery process and describes the advantages that this new technology has brought to field operations.

The method involves delivering polyacrylamide powder for slickwater fracturing treatments directly into the source water on location, thereby eliminating the use of liquid polymer slurries or emulsions. Liquid friction reducers typically contain 20-30% active polymer loading, with the remaining volume being the carrier fluid to keep the polymer in suspension. By delivering 100% powder, several benefits are gained including elimination of truck deliveries of FR liquids to location, reduction of total chemical volumes by 70-80%, reduction of spill hazards, and lower overall chemical costs. Different powders are available for various applications including the use of fresh or produced water, and viscosifying or non-viscosifying polymers.

The key technology for "dry on the fly" (DOTF) operations is the powder delivery equipment. Due to the different molecular structures between polyacrylamide and guar polymers, delivering PAM is more technically challenging than guar and requires much higher mixing energy to achieve proper dispersion and hydration. The delivery system described in this paper uses a unique technology which creates the necessary conditions for powder mixing and has been successfully applied on over 350 wells since early 2019, with over 7,000 tons of polymer delivered.
Joint Pressure and Production Analysis to Understand Inter- and Intra-Zone Well Interference: A Midland Basin Case Study
Authors: Ji Qin , Vernon Geoff , Mata Juan , Klier Shannon , Perry Matthew , Garcia Allie , Coenen Erica
Published: April 2021

This paper demonstrates how to use pressure data from offset wells to assess fracture growth and evolution through each stage by quantifying the impacts of nearby parent well depletion, completion design, and formation. Production data is analyzed to understand the correlation between fracture geometries, well interactions, and well performance.

The dataset in this project includes three child wells and one parent well, landed within two targets of the Wolfcamp B reservoir in the Midland Basin. The following workflow helped the operator understand the completion design effectiveness and its impact to production:Parent well pressure analysis during completionIsolated stage offset pressure analysis during completionOne-month initial production analysis followed by one month shut-inPressure interference test: sequentially bringing wells back onlineProduction data comparison before and after shut-in period

An integrated analysis of surface pressure data acquired from parent and offset child wells during completions provides an understanding of how hydraulic dimensions of each fracture stage are affected by fluid volume, proppant amount, frac stage order of operations, and nearby parent well depletion. Production data from all wells was analyzed to determine the impact of depletion on child well performance and to investigate the effects of varying completion designs. A pressure interference test based on Chow Pressure Group was also performed to further examine the connectivity between wells, both inter- and intra-zone.

Surface pressure data recorded from isolated stages in the offset child wells during completions was used to resolve geometries and growth rates of the stimulated fractures. Asymmetric fracture growth, which preferentially propagates toward the depleted rock volume around the parent well, was identified at the heel of the child well closest to the parent. Fracture geometries of various child well stage groups were analyzed to determine the effectiveness of different completion designs and the impact of in situ formation properties. Analysis of parent well surface pressure data indicates that changing the completion design effectively reduced the magnitude of Fracture Driven Interactions (FDIs) between child and parent wells. Child well production was negatively impacted in the wells where the fracture boundary overlapped with the parent well depleted volume in the same formation zone.

This study combines pressure and production analyses to better understand inter- and intra-zone interference between wells. The demonstrated workflow offers a very cost-effective approach to studying well interference. Observing and understanding the factors that drive fracture growth behavior enables better decision-making during completion design planning, mitigation of parent-child communication, and enhancement of offset well production.
Achieving Perfect Fluid and Proppant Placement in Multi-Stage Fractured Horizontal Wells: A CFD Modeling Approach
Authors: Liu Xinghui , Wang Jiehao , Singh Amit , Rijken Margaretha , Chrusch Larry , Wehunt Dean , Ahmad Faraj , Miskimins Jennifer
Published: April 2021

Multi-stage plug-n-perf fracturing of horizontal wells has proven to be an effective method to develop unconventional reservoirs. Various studies have shown uneven fluid and proppant distributions across all perforation clusters. It is commonly believed that both fracturing fluid and proppant contribute to unconventional well performance. Achieving uniform fluid and proppant placement is an important step toward optimal stimulation. This paper discusses how to achieve such uniform placement in each stage via a CFD (Computational Fluid Dynamics) modeling approach.

CFD models in several lab scales were built and calibrated using experimental data of proppant transport through horizontal pipes in several laboratory configurations. A field-scale model was then built and validated using perforation erosion data from downhole camera observations and the same model parameters calibrated in the lab-scale model. With the field-scale model validated, CFD simulations were performed to evaluate the impact of key parameters on fluid and proppant placement in individual perforations and clusters. Some key parameters investigated in this study included perforation parameters (size, orientation, number), cluster spacing, cluster count per stage, fluid properties, proppant properties, pumping rates, casing sizes, and stress shadow effects, etc.

Both lab and CFD results show that bottom-side perforations receive significantly more proppant than top-side perforations due to gravitational effects. Lab and CFD results also show that proppant distribution is increasingly toe-biased at higher rates. Proppant concentration along the wellbore from heel to toe generally varies significantly. Gravity, momentum, viscous drag, and turbulent dispersion are key factors affecting proppant transport in horizontal wellbores.

This study demonstrates that near-uniform fluid and proppant placement across all clusters in each stage is achievable by optimizing perforation, cluster, and other treatment design factors. Validated CFD modeling plays an important role in this design optimization process.