bluuebunny/crossref_metadata_2025_split huggingface dataset:
Visual Analysis on the Effects of Fracture-Surface Characteristics and Rock Type on Proppant Transport in Vertical Fractures
Authors: Huang Hai , Babadagli Tayfun , Andy Li Huazhou , Develi Kayhan 
Published: January 2018

Abstract
The fracture-surface characteristics (such as roughness and fractal dimensions) may greatly affect the proppant transport during hydraulic fracturing operation. Few researches have focused on investigating the proppant transport in vertical fracture with actual surface characteristics. As a continuation of our previous study (Huang et al. 2017), we qualitatively investigatethe migration of proppants in rough and vertical fractures by considering the effects of surface characteristics and rock type on the instantaneous transport and areal spreading of proppant in the fractures. We fractured different types of tight rocks (including limestone, marble, tight sandstone, and granite) with Brazilian test and molded them to manufacture 20×20cm transparent replicas with an aperture of 1 mm. We characterized the surface characteristics of these rock samples with different fractal dimensions. Subsequently, dyed fracturing fluid with or without proppant loading was injected into the rough vertical fracture. In each test, we monitored the inlet pressure continuously while the proppants were being transported in the fracture. The process was videotaped to monitor the proppant distribution in the rough fracture. Different from our previous study (Huang et al. 2017), a higher injection rate is used in this present study. The experimental results obtained in this study further consolidate the many findings reported in our recent study (Huang et al. 2017): in rough and narrow fracture, the surface roughness plays a pivotal role in affecting how proppants settle in the fracture as well as where the proppants settle in the fracture. Roughness of the vertical fractures tends to significantly enhance the vertical placement of proppants in the fracture, leading to a much higher proppant-filling ratio in a rough fracture than in a smooth fracture. Interestingly, in addition to the bridging effect observed in Huang et al. (2017), a previously formed proppants cluster can be broken up under a higher-rate slurry flow. The bridging of proppants and its subsequent breaking up can recursively occur during the high-rate slurry flow, resulting in fluctuations in the proppant filling ratios as well as fluctuations in the pressure profiles recorded in the inlet of the fracture model. The roughness of fracture models not only affects how much area of the fracture is being occupied by the proppants in the fracture, but also affects how tightly the proppants are filling up the fracture. Different types of rock have different surface characteristics, leading to the observed differences with regard to how the proppants migrate, settle down and fill up the fractures. No definite correlation could be established between any of the fractal numbers and the relative coverage of proppants in the fracture. More experiments, however, need to be conducted to reach more concrete conclusions in this regard.
Flowback-Based Minimum Stress Estimate in Low-Permeability Environment: Procedure, Interpretation, and Application in the Vaca Muerta Shale
Authors: Pichon Stephane , Varela Raul , Manière Jérôme , Hasbani Jose , d'Huteau Emmanuel 
Published: January 2018

Abstract
Low-permeability formations must be hydraulically fractured to produce at commercial rates. A good understanding of the formation stress conditions is critical for completion design, but requires in-situ measurement as calibration to support the geomechanical evaluation. This calibration is commonly done using diagnostic formation injection test (DFIT) methodology by creating a hydraulic fracture and then waiting for it to close through leakoff to the formation. However, in a low-permeability low-leakoff environment, application of this approach might become limited because of the time to fracture closure and the non-uniqueness of the interpretation. This paper demonstrates the applicability of the fracture flowback method to define closure pressure. Although proposed in the 1980s, this method has been underused by the industry. One of the objectives of this paper is, therefore, to advocate through field examples its simplicity of development, interpretation, and repeatability, particularly in low-leakoff reservoirs such organic shale formations.
The procedure is composed of a sequence of various cycles of pump-in flowback through a fixed choke, pressure rebound, and fracture reopening. The proposed methodology offers several minimum stress measurements for repeatability and quality check purposes, reduces interpretation non-uniqueness, and can be completed within 1 hour, making it compatible with the hydraulic fracturing operations.
Test design considerations, such as well geometry, pump rate, fluid volume, choke size, or perforation requirements, are reviewed to maximize the chance of success. Interpretation of the different possible patterns that can be observed is discussed and illustrated with practical examples from the Vaca Muerta shale. Comparison is made between the pump-in flowback and calibration decline approaches performed over the same interval. Repeatability is evaluated, and discrepancies between cycles are investigated.
A direct application of the method is the calibration of a stress profile when applied to a vertical well. However, additional observations related to the fracture closure mechanism or residual fracture conductivity can be drawn by detailing the flowed-back volumes or rate of rebound pressure. These observations can be related to the lithology when the procedure is implemented in different intervals of the same formation.
New API Standards for Shale Development
Authors: Benge Glen , Miller David , Miller Stephanie , Goodman Roland 
Published: January 2018

Abstract
The American Petroleum Institute (API) is the only national trade association representing all facets of the oil and natural gas industry whose mission is to promote safety across the industry globally and to influence public policy in support of a strong, viable U.S. oil and natural gas industry. For almost 100 years, API has led the development of petroleum and petrochemical equipment and operating standards. These represent the industry's collective wisdom on everything from drill bits to environmental protection and embrace proven, sound engineering and operating practices and safe, interchangeable equipment and materials.
In support of increased use of hydraulic fracturing, new editions of API's hydraulic fracturing standards have been developed to provide the latest technical direction for operators working to continuously improve well integrity, groundwater protection, and environmental safety. API's standards for shale development have worked alongside robust state regulations to ensure safe and responsible energy development with hydraulic fracturing for over 65 years.
Dubbed ANSI/API RP 100-1 and 100-2, the new standards provide guidance and recommendations for pressure containment and well integrity, as well as environmental safeguards, including groundwater protection, waste management, emissions reduction, site planning, and worker training. The release follows publication of ANSI/API Bulletin 100-3, which outlines community engagement guidelines to assist operators communicate effectively with residents and stakeholders to pursue mutual goals for community growth.
This paper will provide an overview of the developed global standards that emphasize three core principals of integrity, safety and environmental responsibility, and effective communication. Key focus areas of the paper outline how the standards address well integrity and fracture containment, environmental aspects associated with well construction and fracturing operations, and communication guidance for communities and other key stakeholders.
Interaction Between Hydraulic Fracture and a Preexisting Fracture under Triaxial Stress Conditions
Authors: Mighani Saied , Lockner David A. , Kilgore Brian D. , Sheibani Farrokh , Evans Brian 
Published: January 2018

Abstract
Enhanced reservoir connectivity generally requires maximizing the intersection between hydraulic fracture (HF) and preexisting underground natural fractures (NF), while having the hydraulic fracture cross the natural fractures (and not arrest). We have studied the interaction between a hydraulic fracture and a polished saw-cut fault. The experiments include a hydraulic fracture initiating from a pressurized axial borehole (using water) that approaches a dry fault that is inclined at an angle θ with respect to the borehole axis. The experiments are conducted on Poly(methyl) Meta Acrylate (PMMA) and Solnhofen limestone, a finely grained (&lt;5 μm grain), low permeability (&lt;10 nD) carbonate. The confining pressure in all experiments is 5 MPa, while the differential stress (1-80 MPa) and approach angle, θ (30, 45, 60, 90°) are experimental variables. During the hydraulic fracture, acoustic emissions (AE), slip velocity, slip magnitude, stress drop and pore pressure are recorded at a 5 MHz sampling rate. A Doppler laser vibrometer measures piston velocity outside the pressure vessel to infer fault slip duration and a strain gauge adjacent to the saw-cut provides a near-field measure of axial stress.
For PMMA, the coefficient of friction was 0.30 and sliding was unstable (stick-slip). The approaching HF in PMMA created a tensile fracture detected by AE transducers ~100 μs before the significant stick-slip event (45% stress drop and slip velocity of ~60 mm/s) and was arrested by the fault at all fault orientations and differential stresses, even at 90° fault orientation and 80 MPa differential stress. For Solnhofen limestone, we observed stable sliding at a coefficient of friction of 0.12. In contrast to PMMA, the HF in Solnhofen consistently crossed to the other side of the fault. When the HF crossed the fault, it produced a small stress drop (&lt;10%) and slip velocity of only 0.5 mm/s. Theoretical models by Blanton (1986) and Renshaw and Pollard (1995) predict that HF will be arrested for Solnhofen limestone and cross PMMA 90° fault at 80 MPa differential stress. Although the exact cause for the discrepancy between experiments and the theory is not known, one feature present in the experiments but not considered in the models, is the diffusion of fluid driven by the fault slip. Thus, the formation of a "fluid-filled patch" on the fault surface as it is intersected by the HF may substantially impact the crossing/arrest behavior. The approach angle and differential stress also influence the HF initiation azimuth and breakdown pressure. In most cases, the HF initiation azimuth was normal to the fault strike. These observations suggest that the presence of natural fractures could result in rotation of hydraulic fractures to be more normal to their strike and a subsequent change in the downhole pressure recordings. The latter could be used as a diagnostic tool for predicting this interaction.
Osgood-schlatter Disease Diagnosis by Algometry and Infrared Thermography
Authors: Capitani Gabriel , Sehnem Eduardo , Rosa Claudio , Matos Filipe , Reis Victor M. , Neves Eduardo B. 
Published: January 2018

Background:
The diagnosis of Osgood-Schlatter Disease (OSD) is based on clinical signs and symptoms. However, more objective parameters, like thermal images, have been researched to determine, along algometry, valid parameters.

Objective:
The aim of this study was to analyze the thermal differences and the painful sensibility between the knees (with SOS and contralateral) of young soccer players.

Methods:
6 young men, aged between 12 and 15, members of football schools, composed the sample. Images were taken from an anterior view of both knees, with the volunteer in a seated position, the knees flexed at 90º degrees and both feet flat on the floor. After the thermal image capture, the patients were submitted to an evaluation with the pressure algometer.

Results:
According to the results, it was found that the knee affected by the OSD showed temperatures significantly higher than the contralateral (p = 0.027) and also greater sensitivity to the pressure algometry (p = 0.027).

Conclusion:
it can be concluded that the inflammatory process, during OS Syndrome, promotes a local thermal hyper-radiation, identified with the high sensitive thermographic infrared image, producing a significant difference in local temperature between the knees of a single individual. Moreover, this process also increases the pain sensibility, accessed by pressure algometry.
Determinative Factors in The Injury Incidence on Runners: Synthesis of Evidence “Injuries on Runners”
Authors: Zaar Andrigo , Neves Eduardo Borba , Rouboa Abel Ilah , Reis Victor Machado 
Published: January 2018

Background:Long-distance running is a popular recreational exercise. It is a beneficial activity for health and wellness. However, the running can also cause injury, particularly in the lower extremities. There is no consensus in the literature on the intrinsic and extrinsic factors that cause these musculoskeletal injuries. In theory, most injuries are caused by methodological errors, the type of footwear and terrain.Objective:To identify the factors associated with injuries in recreational runners based on evidence.Method:The data sources used were: PubMed, Science Direct and Web of Science. Compiled the English-language articles identified by keywords, titles of medical affairs and research of electronic databases above. With this research from the review process, controlled trials were grouped in a study population consisted of recreational runners.Results:Evidences suggest that injuries are common for runners. Many variables can contribute to the injury process, among them extrinsic factors such as training methodology, running shoes and surface.Conclusion:To modify one or more of these factors may help prevent injury, so coaches and runners should consider it, and prevention efforts need to be tailored to this group to reduce the risk of specific injuries.
Increased Risk of Severe Hypoglycemic Events Before and After Cardiovascular Outcomes in TECOS Suggests an At-Risk Type 2 Diabetes Frail Patient Phenotype
Authors: Standl Eberhard , Stevens Susanna R. , Armstrong Paul W. , Buse John B. , Chan Juliana C.N. , Green Jennifer B. , Lachin John M. , Scheen Andre , Travert Florence , Van de Werf Frans , Peterson Eric D. , Holman Rury R. 
Published: January 2018

OBJECTIVE
Severe hypoglycemic events (SHEs) in type 2 diabetes are associated with subsequent cardiovascular (CV) event risk. We examined whether CV events were associated with subsequent SHE risk.

RESEARCH DESIGN AND METHODS
Time-dependent associations between SHEs and a composite CV end point (fatal/nonfatal myocardial infarction or stroke, hospitalization for unstable angina, hospitalization for heart failure [hHF]) were examined post hoc in 14,671 TECOS (Trial Evaluating Cardiovascular Outcomes With Sitagliptin) participants with type 2 diabetes and CV disease followed for a median of 3.0 years.

RESULTS
SHEs were uncommon and unassociated with sitagliptin therapy (N = 160 [2.2%], 0.78/100 patient-years vs. N = 143 [1.9%], 0.70/100 patient-years for placebo; hazard ratio [HR] 1.12 [95% CI 0.89, 1.40], P = 0.33). Patients with (versus without) SHEs were older with longer diabetes duration, lower body weight, and lower estimated glomerular filtration rate; were more frequently women, nonwhite, and insulin treated; and more often had microalbuminuria or macroalbuminuria. Analyses adjusted for clinical factors showed SHEs were associated with increased risk of the primary composite CV end point (1.55 [1.06, 2.28], P = 0.025), all-cause death (1.83 [1.22, 2.75], P = 0.004), and CV death (1.72 [1.02, 2.87], P = 0.040). Conversely, nonfatal myocardial infarction (3.02 [1.83, 4.96], P &lt; 0.001), nonfatal stroke (2.77 [1.36, 5.63], P = 0.005), and hHF (3.68 [2.13, 6.36], P &lt; 0.001) were associated with increased risk of SHEs. Fully adjusted models showed no association between SHEs and subsequent CV or hHF events, but the association between CV events and subsequent SHEs remained robust.

CONCLUSIONS
These findings, showing greater risk of SHEs after CV events and greater risk of CV events after SHEs, suggest a common at-risk type 2 diabetes frail patient phenotype.
Efektivitas Penerapan Konseling Rational Emotive Behavior Therpy (REBT) untuk Menghilangkan Kecemasan pada Klien
Authors: Dharmayana I Wayan , Sinthia Rita , Afriyati Vira 
Published: January 2018

Artikel ini bertujuan untuk memaparkan kajian tentang pengaruh konseling REBT dalam mengatasi kecemasan. Kecemasan dapat terjadi pada setiap individu.Seseorang yang menderita kecemasan selalu merasa khawatir dan selalu bereaksi berlebihan. Keluhan fisik yang lazim terjadi antara lain adalah tidak tenang, tidur terganggu, kelelahan, sakit kepala, dan jantung berdebar-debar. Individu terus menerus mengkhawatirkan segala macam masalah yang mungkin terjadi dan sulit sekali berkonsentrasi atau mengambil keputusan. Konseling untuk dapat meminimalisir bahkan menghilangkan perasaan cemas yang berlebihan menjadi sangat penting. Kecemasan dilatarbelakangi oleh pemikiran yang irasional cenderung menimbulkan gangguan. Konseling REBT adalah suatu pendekatan konseling yang menangani masalah-masalah yang berhubungan dengan emosi, kognisi dan tingkahlaku, dengan merubah cara pandang klien yang semula irasional menjadi rasional. Tujuan REBT memperbaiki dan mengubah segala pemikiran yang irasional dan tidak logis menjadi rasional dan logis agar klien dapat mengembangkan dirinya. Beberapa hasil penelitian secara konsisten menegaskan bahwa Konseling REBT mempunyai pengaruh dalam mengurangi kecemasan yang ditunjukkan dengan adanya perubahan pola pikir klien menjadi rasional, sehingga perasaan dan tingkahlaku klien dapat berkembang dengan baik dan optimal.
Calculating real surface area of land parcels in hilly and mountainous regions
Authors: Tran Quoc Binh , Xuan Pham Thanh , Tuan Pham Le , Thuy Le Phuong , Linh Nguyen Xuan , Huy Man Quang 
Published: January 2018

Currently, the legal area of a land parcel in cadastral map is defined as the projected area of the parcel on a map plane. However, in practice, the real surface area of parcels plays important role for land use. In plain regions, the differences between real and legal areas of parcels are negligible, but in hilly and mountainous regions, these differences are significant and must be accounted in land management.
In this paper, the authors had proposed a method for calculating real surface area of land parcels using GIS and data extracted from digital elevation models. The method was verified against Vietnam’s standard on cadastral map by using a simulated land parcel that is a part of a sphere, and got positive results. The method is then applied for calculating surface area of more than 2000 land parcels in Tien Xuan Commune, Thach That District, Hanoi City. The obtained results showed that the differences between real and legal areas of land parcels can reach a value of 23% for forestry land at mountain side with slope of more than 30o. In whole Tien Xuan Commune, these differences have an average value of 2.4%.
A Dinâmica de Expansão e Retração de Cerrados e Caatingas no Período Quaternário: uma Análise Segundo a Perspectiva da Teoria dos Refúgios e Redutos Florestais (The Dynamics of Expansion and Contraction in Cerrado and Caatinga Quaternary Period: An .....)
Authors: Silva Márcio Luiz 
Published: January 2018

A dinâmica da vegetação no espaço e no tempo sempre se apresentou como uma incógnita para os estudiosos das geociências. No Brasil, a expansão e retração vegetacional aparece como uma problemática ainda maior devido à complexidade e diversidade de paisagens. Assim, esse artigo aborda o processo de expansão e retração de cerrados e caatingas durante o Período Quaternário segundo a ótica da Teoria dos Refúgios e dos Condicionantes Geoambientais. A perspectiva da Teoria dos Refúgios, baseada em estudos de interpretação de paleoclimas, de paleossolos, de formas geomorfológicas e aliada a análises palinológicas e de carbono 14, se constitui um importante mecanismo para explicar a dinâmica fitogeográfica, principalmente no Brasil, a partir do Período Quaternário. Mas condições geoambientais regionais ou locais têm contribuído para a configuração atual da vegetação brasileira, principalmente do cerrado e da caatinga, que exigem certas características climáticas, geomorfológicas, pedológicas e hidrológicas do ambiente para se adaptarem. Palavras-chave: Cerrados, Caatingas, Teoria dos Refúgios, Condicionantes Geoambientais, Período Quaternário. The Dynamics of Expansion and Contraction in Cerrado and Caatinga Quaternary Period: An Analysis According to the Theory Perspective Rfuges and Forest of Strongholds ABSTRACTThe dynamics of the vegetation in the space and the time always if presented as an incognito for the investigators of the Geosciences. In Brazil, the expansion and vegetational retraction appear as problem still bigger due to complexity and diversity of landscapes. Thus, this article approaches the process of expansion and retraction of Cerrados and Caatingas during the Quaternary Period according to optics of the Ace Age Forest Refuges Theory and the Geoenvironmental Condictionantes. The perspective of the Ace Age Forest Refuges Theory, based in studies of interpretation of paleoclimates, paleosols, geomorphologicals forms and allied the palinologycals analyses and of carbon 14, if constitutes an important mechanism to explain the phytogeographical dynamics, mainly in Brazil, from the Quaternary Period. But regional or local geoenvironmental conditions have contributed for the current configuration of the Brazilian vegetation, mainly of the cerrado and caatinga, that they demand certain climatic characteristics, geomorphologicals, pedologycals and hydrologicals of the environment to be adapted. KeyWords: Cerrados, Caatingas, Ace Age Forest Refuges Theory, Geoenvironmental Condicionantes, Quaternary Period.